GRC Transactions, Volume 39

Geothermal: always on

Geothermal resources council

2015 annual meetinG

september 20 – 23, 2015peppermill resort

reno, nevada • usa

Goethermal resources council, 630 peña drive, suite 400p. o. box 1350 • davis, california 95617-1350 • usa

ii

Grc TransacTions, volume 39

Geothermal: always on

Geothermal resources council 2015 annual meetinG

proGram committee

General ChairmanLisa ShevenellATLAS Geosciences Inc.

GRC Executive DirectorSteve PonderGeothermal Resources Council

Technical Program ChairmenMariana EnevaImageair, Inc.

Poster Session ChairmanAlexandra ReidUniversity of Nevada, Reno

Fund-Raising ChairmanLisa ShevenellATLAS Geosciences Inc.

Invited Speaker ChairmanDick BenoitSustainable Solutions

Field Trips ChairmanGene A. Suemnicht

EGS, Inc.

Special Events ChairmanLisa Shevenell

ATLAS Geosciences Inc.

Pre-Conference Workshop ChairmanJoe Moore

Energy and Geoscience Institute

Photo Contest ChairmanAnna Crowell

University of North Dakota

International Participation ChairmanRichard Zehner

Geothermal Development Associates

Exhibits LiaisonKarl Gawell

Geothermal Energy Association

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table of Contents

Basin & RangeBenoit, D. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

A Case History of the Dixie Valley Geothermal Field, 1963–2014

Gwynn, M. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Geothermal Potential in the Basins of East-Central and Southeastern Nevada

Kirby, S., S. Simmons , M. Gwynn, R. Allis, and J. Moore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Comparisons of Geothermal Systems in Central Nevada: Evidence for Deep Regional Geothermal Potential Based on Heat Flow, Geology, and Fluid Chemistry

McCurry, M., D. M. Pearson, J. Welhan, S. K. Natwotniak, and M. Fisher . . . . . . . . . . . . . . . . . . . . . . . 2Origin and Potential Geothermal Significance of China Hat and Other Late Pleistocene Topaz Rhyolite Lava Domes of the Blackfoot Volcanic Field, SE Idaho

Moulding, A., and T. Brikowski . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Influence of Continuously Variable Permeability and Basin Rock Properties on Three Dimensional Heat and Mass Balance Models of Basin & Range Geothermal Systems

Simmons, S., S. Kirby, J. Moore, P. Wannamaker, and R. Allis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Comparative Analysis of Fluid Chemistry From Cove Fort, Roosevelt and Thermo: Implications for Geothermal Resources and Hydrothermal Systems on the East Edge of the Great Basin

Country UpdateBoyd, T. L., A. Sifford, and J. W. Lund . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

The United States of America Country Update 2015

Crewson, J., and A. Thompson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Breaking Down the Barriers to Geothermal Energy in Canada: Bridging the Knowledge Gap and Overcoming the Status Quo

Lund, J. W., R. Bertani, and T. L. Boyd. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Worldwide Geothermal Energy Utilization 2015

Williams, C. F., J. DeAngelo, and M. J. Reed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Revisiting the Assessment of Geothermal Resources <90 ºC in the United States

Direct UseDell, R., R. Unnthorsson, C. S. Wei, and W. Foley . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Accelerated Plant Growth Results From an Intensive Shallow Bottom Heat System Using Waste Geothermal Hot Water and Steam Condensate in Iceland

Farabi Asl, H., H. Fujii, and H. Kosukegawa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Heat Exchange Rate Enhancement in Ground Heat Exchangers by Water Injection and Pumping

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Foley, W., R. Dell, C. S. Wei, and R. Unnthorsson. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Point of Use Thermoelectric Powered Automated Irrigation System for an Intesive Shallow Bottom Heat System Using Waste Geothermal Hot Water and Steam Condensate in Iceland

Gehringer, M. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Use of Waste Heat From Geothermal Power Plants Focusing on Improving Agriculture in Developing Countries

Jalilinasrabady, S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Geothermal Direct Utilization-Design and Optimization

Parlaktuna, M. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Evolution of Balçova Geothermal District Heating System — Turkey

Patsa, E., S. J. Zarrouk, and D. Van Zyl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6The Lindal Diagram for Mining Engineering

Uwera, J., R. Itoi, S. Jalilinasrabady, T. Jóhannesson, and D. Ö. Benediktsson . . . . . . . . . . . . . . . . . . . . 6Design of a Cooling System Using Geothermal Energy for Storage of Agricultural Products With Emphasis on Irish Potatoes in Rwanda, Africa

Wei, Z., J. Lv, and L. Jiulong . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Study of Thermal Performance and Operation Strategy of a Compound Ground Source Heat Pump Heating System

DrillingDenninger, K., A. Eustes, C. Visser, W. Baker, D. Bolton, J. Bell, S. Bell, A. Jacobs, U. Nagandran, M. Tilley, and R. Quick . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Optimizing Geothermal Drilling: Oil and Gas Technology Transfer

Kahutu, J., and V. Atwa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Comparison of Drilling Technologies Between Top Drive and Rotary Table in Geothermal Fields: A Case Study of Olkaria Geothermal Fields

Karanja, N. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Challenges of Cementing Olkaria Geothermal Field

Khaemba, A. W. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Well Design and Well Workover to Land Deep Production Casings in the Menengai Field

Miyora, T., M. Þ. Jónsson, and S. Þórhallsson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Modelling of Geothermal Drilling Parameters — A Case Study of Well MW-17 in Menengai Kenya

Pyatina, T., and T. Sugama. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Use of Carbon Microfibers for Reinforcement of Calcium Aluminate-Class F Fly Ash Cement Activated With Sodium Meta-Silicate at up to 300°C

Wilson, D. R., J. Gilliland, and A. Austin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Broaching: An Effective Method of Well Intervention for Calcite Scale Removal

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East African RiftAdmassu, E., and S. Worku . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Characterization of Quaternary Extensional Structures: Tulu-Moye Geothermal Prospect, Ethiopia

Barasa, P. J., and R. W. Mathenge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Stakeholder Engagement Through Participatory Research: A Case Study of Eburru Geothermal Wellhead Generator in Nakuru County, Kenya

Harðarson, B. S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10The Western Branch of the East African Rift: A Review of Tectonics, Volcanology and Geothermal Activity

Ronoh, I. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Evolution and Geology of Eburru-Badlands Geothermal Prospect — Central Kenyan Rift

Wamalwa, R. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10The Initial-State Geochemistry as a Baseline for Geochemical Monitoring at Olkaria Domes, Kenya

Enhanced Geothermal SystemsBradford, J., J. McLennan, J. Moore, R. Podgorney, and S. Tiwari . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Hydraulic and Thermal Stimulation Program at Raft River Idaho, A DOE EGS

Cladouhos, T. T., M. E. Uddenberg, M. W. Swyer, S. Petty, and Y. Nordin . . . . . . . . . . . . . . . . . . . . . . 11Production Well Targeting at Newberry Volcano EGS Demonstration

Dreger, D. S., R. Gritto, and O. S. Boyd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Analysis of Seismic Moment Tensor, Finite-Source Scaling and Fluid Imaging During EGS Resource Development at The Geysers, CA

Farmahini-Farahani, M., and A. Ghassemi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Simulation of Injection and Production and MEQ in Large-Scale Fracture Networks

Faulds, J. E., D. Blankenship, N. H. Hinz, A. Sabin, J. Nordquist, S. Hickman, J. Glen, M. Kennedy, D. L. Siler, A. Robertson-Tait, C. Williams, P. Drakos, and W. Calvin . . . . . . . . . . . . . . . 12

Geologic Setting of the Proposed Fallon Forge Site, Nevada: Suitability for EGS Research and Development

Finnila, A., W. Dershowitz, T. Doe, and R. McLaren . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Hydro-Shearing and Hydraulic Fracturing for Enhanced Geothermal Systems in Archetypical Normal, Strike-Slip, and Thrust Faulting Terrains

Kelkar, S., D. Martinez, D. Brown, and L. House . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Data Archiving and Lessons Learned From the Pioneering Hot Dry Rock Project at Fenton Hill, USA

Li, K., B. Pan, and R. Horne . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Fracture Characterization Using Resistivity Measured at Different Frequencies in Rocks

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Numakura, T., N. Watanabe, K. Sakaguchi, T. Kikuchi, and N. Tsuchiya . . . . . . . . . . . . . . . . . . . . . . . 13Permeability Measurements of Fractured Granite at 350-450 °C Under Confining Stress

Olson, J., A. Eustes, W. Fleckenstein, E. Eker, R. Baker, and C. Augustine . . . . . . . . . . . . . . . . . . . . . . 14Completion Design Considerations for a Horizontal Enhanced Geothermal System

Sabin, A., K. Blake, M. Lazaro, D. Blankenship, M. Kennedy, J. McCullough, S. DeOreo, S. Hickman, J. Glen, O. Kaven, C. Williams, G. Phelps, J. E. Faulds, N. Hinz, W. Calvin, D. Siler, and A. Robertson-Tait . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Geologic Setting of the Proposed West Flank Forge Site, California: Suitability for EGS Research and Development

Vazquez-Rubio, I. G., D. Bahrami, and G. Danko. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Numerical Simulation Model Comparisons for Enhanced Geothermal Reservoirs

Welhan, J. A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Thermal and Trace-Element Anomalies in the Eastern Snake River Plain Aquifer: Toward a Conceptual Model of the EGS Resource

ExplorationAllis, R., C. Hardwick, M. Gwynn, and S. Johnson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Pavant Butte, Utah Geothermal Prospect Revisited

Allis, R., M. Gwynn, C. Hardwick, G. Mines, and J. Moore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Will Stratigraphic Reservoirs Provide the Next Big Increase in U.S. Geothermal Power Generation?

Bellani, S., G. Magro, and F. Gherardi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Heat Flow and Helium Isotopes in the Geothermal Areas of Tuscany (Central Italy)

Blake, K., A. Tiedeman, A. Sabin, M. Lazaro, D. Meade, and W-C. Huang . . . . . . . . . . . . . . . . . . . . . 16Naval Air Station Fallon Mainside: Update of Geothermal Exploration

Lindsey, C., J. Fairley, P. Larson, and N. McMillan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Stochastic Modeling and Analysis of Temperature Data From Hot Springs in Yellowstone Caldera, Wyoming, USA

Lindsey, C., B. Lubenow, J. Fairley, and P. Larson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Ice Box Calorimetry: A Test of Applicability in Non-Steaming Geothermal Areas

Mellors, R. J., V. Camp, D. Harris, and A. Al-Amri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Investigating Potential Geothermal Resources in Western Saudi Arabia

Mink, L., J. Smith, K. Skeehan, and P. Foley . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Plumbing and Political Will: Low Temperature Geothermal Power Exploration in Pagosa Springs, Colorado

Siler, D. L., J. E. Faulds, and N. H. Hinz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Earthquake-Related Stress Concentrations and Permeability Generation in Geothermal Systems

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GeochemistryChandrasekhar, V., D. Chandrasekharam, G. Trupti, and H. K. Singh . . . . . . . . . . . . . . . . . . . . . . . . . 18

Fluoride in Geothermal Waters, India

Libbey, R. B., and A. E. Williams-Jones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Applications of Downhole Lithogeochemistry to Geothermal Exploration

McConville, E. G., P. Candela, P. Piccoli, and J. Moore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Variations in the Composition of Epidote in the Karaha-Telaga Bodas Geothermal System

Mizushima, A., H. Mikada, and J. Takekawa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18The Importance of Hydrodynamic Conditions in Silicate Scale Growth Inferred From Numerical Simulation

Neupane, G., E. D. Mattson, T. L. McLing, P. F. Dobson, M. E. Conrad, T. R. Wood, C. Cannon, and W. Worthing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Geothermometric Temperature Comparison of Hot Springs and Wells in Southern Idaho

Wamalwa, R. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Assessment of the Downhole Geochemical Report of OW-917

Zarei, E., F. Tutti, S. Porkhial, and N. M. Astanah. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Geochemistry and Alteration Mineralogy of Well NWS-10, Mt. Sabalan Geothermal Field, NW-Iran

GeologyCallahan, O. A., T. T. Cladouhos, B. Larson, and R. A. Ketcham . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

The Thermal History of Garland Mineral Springs, North Cascades, Washington, From Apatite Fission Track Analysis of Well Cuttings From Geothermal Exploration Well GAR-1

Etzel, T. M., J. N. Moore, J. R. Bowman, C. G. Jones, R. G. Intani, G. Golla, and G. Nash . . . . . . . . . 20Tourmaline in Geothermal Systems: An Example From Darajat, Indonesia

Harðarson, B. S., S. G. Kristinsson, R. Karlsdóttir, and G. M. Einarsson . . . . . . . . . . . . . . . . . . . . . . . . 20Geothermal Implications of Rift Zone Mini-Grabens—Geological and Geophysical Structure of the Reykjafell Mini-Graben, Hengill Geothermal Field, SW Iceland

Lynne, B. Y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Examining Subsurface Processes Captured in Geothermal Host Rocks Using Com-puterised Tomography and Scanning Electron Microscopy

Molisee, D. D., and J. W. Bell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Structural Constraints of Buffalo Valley Hot Springs, North-Central Nevada

Mwania, M. M. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Evaluation of Subsurface Structures Using Hydrothermal Alteration Mineralogy — A Case Study of Olkaria South East Field

Ruiz, D. A. R, and R. H. Zúñiga . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Distribution of Hydrothermal Alteration in the Cerritos Colorados Geothermal Field, Mexico

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Sadowski, A. J., and J. E. Faulds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Structural Controls of the Black Warrior Blind Geothermal System, Washoe-Churchill Counties, Truckee Range, Northwestern Nevada, USA

GeophysicsCrowell, J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Quantifying How Errors in Thermal Conductivity Estimates Affect Geothermal Production Models

Durán, E., K. van Wijk, L. Adam, and I. Wallis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Separating Intrinsic From Scattering Seismic Wave Attenuation From Sonic Logs in a Geothermal Field

Hardwick, C. L., R. Allis, and P. E. Wannamaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Observations and Implications of Magnetotelluric Data for Resolving Stratigraphic Reservoirs Beneath the Black Rock Desert, Utah, USA

Hartline, C. S., M. A. Walters, and M. C. Wright . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Three-Dimensional Structural Model Building, Induced Seismicity Analysis, Drilling Analysis, and Reservoir Management at The Geysers Geothermal Field, Northern California

Hutchings, L., J. Savy, C. Bachmann, O. Heidbach, M. Miah, N. Lindsey, A. Singh, and R. Laboso. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Examination of a Site-Specific, Physics-Based Seismic Hazard Analysis, Applied to Surrounding Communities of The Geysers Geothermal Development Area

McDonald, M. R., W. D. Gosnold, and S. H. Nordeng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Preliminary Results of a Heat Flow Study of the Williston Basin Using Temporarily Abandoned Oil Wells, Western North Dakota

Rahayu, D. M., and H. E. H. Fatahillah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Magnetic Analysis of Dieng-Batur Geothermal Area

Sugihara, M., K. Nawa, T. Ishido, N. Soma, and Y. Nishi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Potentiality of Continuous Measurements Using a Small-Sized Superconducting Gravimeter for Geothermal Reservoir Monitoring

InjectionCui, M., H. Lei, and C. Dai . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Particle Deposition in Porous Media: A Review

Oil & GasGosnold, W., A. Crowell, S. Nordeng, and M. Mann. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Co-Produced and Low-Temperature Geothermal Resources in the Williston Basin

Hardwick, C. L., H. W. Willis, and M. L. Gwynn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25A Basin-Scale Geothermal Assessment of Co-Produced Waters in Oil and Gas Fields: Uinta Basin, Utah, USA

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Wendt, D. S., G. L. Mines, C. J. Orme, and A. D. Wilson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Produced Water Treatment Using Switchable Polarity Solvent Forward Osmosis (SPS FO) Technology

Play FairwaysCoolbaugh, M., L. Shevenell, N. H. Hinz, P. Stelling, G. Melosh, W. Cumming, C. Kreemer, and M. Wilmarth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Preliminary Ranking of Geothermal Potential in the Cascade and Aleutian and Volcanic Arcs, Part III: Regional Data Review and Modeling

Faulds, J. E., N. H. Hinz, M. F. Coolbaugh, L. A. Shevenell, D. L. Siler, C. M. dePolo, W. C. Hammond, C. Kreemer, G. Oppliger, P. E. Wannamaker, J. H. Queen, and C. F. Visser . . . . . . . 26

Integrated Geologic and Geophysical Approach for Establishing Geothermal Play Fairways and Discovering Blind Geothermal Systems in the Great Basin Region, Western USA: A Progress Report

Forson, C., M. W. Swyer, G. M. Schmalzle, J. L. Czajkowski, T. T. Cladouhos, N. Davatzes, D. K. Norman, and R. A. Cole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Geothermal Play-Fairway Analysis of Washington State Prospects

Gutiérrez-Negrín, L. C. A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Cerro Prieto, Mexico — A Convective Extensional Geothermal Play

Hinz, N. H., M. Coolbaugh, L. Shevenell, G. Melosh, W. Cumming, and P. Stelling . . . . . . . . . . . . . 27Preliminary Ranking of Geothermal Potential in the Cascade and Aleutian Volca-nic Arcs, Part II: Structural — Tectonic Settings of the Volcanic Centers

Jordan, T., E. Camp, J. Smith, C. Whealton, F. Horowitz, J. Stedinger, J. Tester, M. Richards, M. Hornbach, Z. Frone, R. Bolat, B. Anderson, X. He, and K. Welcker . . . . . . . . . . . . . 28

Low-Temperature Geothermal Energy Characterization by Play Fairway Analysis for the Appalachian Basin of New York, Pennsylvania and West Virginia

Lautze, N., D. Thomas, N. Hinz, N. Frazer, G. Ito, D. Waller, H. Schuchmann, and M. Brady . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Integration of Data in a Play Fairway Analysis of Geothermal Potential Across the State of Hawaii

McClain, J. S., P. Dobson, C. Cantwell, M. Conrad, C. Ferguson, A. Fowler, E. Gasperikova, W. Glassley, S. Hawkes, P. Schiffman, D. Siler, N. Spycher, C. Ulrich, Y. Zhang, and R. Zierenberg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Geothermal Play Fairway Analysis of Potential Geothermal Resources in NE California, NW Nevada, and Southern Oregon: A Transition between Extension-Hosted and Volcanically-Hosted Geothermal Fields

Nash, G. D., and C. R. Bennett . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Adaptation of a Petroleum Exploration Tool to Geothermal Exploration: Preliminary Play Fairway Model of Tularosa Basin, New Mexico, and Texas

Person, M., S. Kelley, R. Kelley, S. Karra, D. Harp, J. Witcher, J. Bielicki, G. Sutula, R. Middleton, and J. D. Pepin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Hydrogeologic Windows: Detection of Blind and Traditional Geothermal Play Fairways in Southwestern New Mexico Using Conservative Element Concentrations and Advective-Diffusive Solute Transport

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Shervais, J. W., J. M. Glen, L. M. Liberty, P. Dobson, E. Gasperikova, E. Sonnenthal, C. Visser, D. Nielson, S. Garg, J. P. Evans, D. Siler, J. DeAngelo, N. Athens, and E. Burns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Snake River Plain Play Fairway Analysis – Phase 1 Report

Shevenell, L., M. Coolbaugh, N. H. Hinz, P. Stelling, G. Melosh, W. Cumming, and C. Kreemer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Preliminary Ranking of Geothermal Potential in the Cascade and Aleutian Volcanic Arcs, Part I: Data Collection

Wannamaker, P. E., A. J. Meigs, B. M. Kennedy, J. N. Moore, E. L. Sonnenthal, V. Maris, and J. D. Trimble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Play Fairway Analysis of the Central Cascades Arc-Backarc Regime, Oregon: Preliminary Indications

Wannamaker, P.E., J. N. Moore, K. L. Pankow, S. D. Simmons, G. D. Nash, V. Maris, C. Batchelor, and C. L. Hardwick . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Play Fairway Analysis of the Eastern Great Basin Extensional Regime, Utah: Preliminary Indications

Power PlantAgahi, R., and F. Mohr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Evaluation of Inflow Radial Turbo Expander Field Performance for a 25 MW Geothermal Organic Rankine Cycle Train

Avery, J., B. Benn, K. E. McIntush, D. Mamrosh, and C. Beitler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Use of a Waste Heat Boiler to Capture Energy From Flammable Noncondensable Gas at Geothermal Power Plants

Bierre, E., and R. Fullerton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Tubular Biofilm Reactor for Hydrogen Sulphide Removal From Geothermal Cooling Water

Bonafin, J., C. R. di Schio, and A. Duvia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Turboden, a Presentation of Recent Worldwide Developments and the Latest Technical Solutions for Large-Scale Geothermal ORC Power-Plants

DiPippo, R., and K. Kitz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Geothermal Binary Power Plants at Raft River, San Emidio, and Neal Hot Springs: Part 1 — Plant Descriptions and Design Performance Comparison

García-Gutiérrez, A., R. Ovando-Castelar, J. I. Martínez-Estrella, I. Canchola-Félix, and P. V. Jacobo-Galván . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Evaluation and Optimization of the Cerro Prieto Geothermal Field Steam Transportation Network Efficiency — Estimation of Heat Losses From Pipe Fittings

Huang, D., Z. Wang, and W. Fu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Predictive Functional Control Applied in Vapor Temperature Control of Organic Rankine Cycle System

Inanli, M., and P. Valdimarsson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Rerouting the Condensate in an ORC Geothermal Power Plant

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Kolar, M., S. Osgood, and W. Echt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Coso Case Study: 22 Years of Reliable Sulfur Removal

Reede, C., H. Doumanidis, M. Aureli, and M. Curie . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Thrust Bearing Load Observations in Deep Well Enclosed Lineshaft Pumps

Rivas-Cruz, F., A. García-Gutiérrez, J. I. Martínez-Estrella, and Á. A. Ortiz-Bolaños . . . . . . . . . . . . . . 34Design and Evaluation of Geothermal Steam Separators: A Review of the State of Art

Shurtleff, P., and W. Harvey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Displaced Exergy: The Valuation of Thermal Power

Wendt, D., G. L. Mines, C. S. Turchi, G. Zhu, S. Cohan, L. Angelini, F. Bizzarri, D. Consoli, and A. De Marzo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Stillwater Hybrid Geo-Solar Power Plant Optimization Analyses

Williams, T., and Greg Mines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35DOE-GTO Low Temperature Project Case Study

Wolf, N., and A. Gabbay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Sarulla 330 MW Geothermal Project Key Success Factors in Development

Regulatory

Ndetei, C. J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Assessment of Air Quality for Development Options at Olkaria Geothermal Field in Kenya

Norris, T. R., and K. DeAnda. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Progress in Silencing ORC Turboexpanders in Geothermal Service

Schroeder, J. N., R. M. Horner, C. B. Harto, and C. E. Clark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Alternative Water Policy Assessment for Enhanced Geothermal Systems — A Case Study

Reservoir Engineering / Modeling

Kumar, D., and A. Ghassemi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363D Simulation of Mixed-Mode Poroelastic Fracture Propagation for Reservoir Stimulation

Ratouis, T. M. P., M. J. O’Sullivan, and J. P. O’Sullivan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Modelling the Effects of Seasonal Variations in Rainfall and Production Upon the Aquifer and Surface Features of Rotorua Geothermal Field

Zerpa, L. E., J. Cho, and C. Augustine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Assessing the Effect of Realistic Reservoir Features on the Performance of Sedimentary Geothermal Systems

Zhang, Y., T. S. Manley, K. Li, and R. N. Horne . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37DNA-Encapsulated Silica Nanoparticle Tracers for Fracture Characterization

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Resource AssessmentGetman, D., A. Anderson, and C. Augustine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Geothermal Prospector: Supporting Geothermal Analysis Through Spatial Data Visualization and Querying Tools

Terry, R., and K. Young . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Using Geothermal Play Types as an Analogue for Estimating Potential Resource Size

Young, K. R., A. M. Wall, and P. F. Dobson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38Geothermal Resource Reporting Metric (GRRM) Developed for the U.S. Department of Energy’s Geothermal Technologies Office

Resource ManagementBergfeld, D., R. G. Vaughan, W. C. Evans, and E. Olsen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Monitoring Ground-Surface Heating During Expansion of the Casa Diablo Production Well Field at Mammoth Lakes, California

Scaling & Mineral ExtractionClemente, V. C., K. S. Faja, M. H. Reed, L. M. Daco-ag, and R. J. T. Tamboboy . . . . . . . . . . . . . . . . . . 39

Assessment of CHIM-XPT and Watch in Predicting the Calcite Scaling Potential of Geothermal Wells

Noack, C. W., K. Perkins, N. Washburn, D. A. Dzombak, and A. K. Karamalidis . . . . . . . . . . . . . . . . 39Screening the Effects of Ligand Chemistry and Geometry on Rare Earth Element Partitioning From Saline Solutions to Functionalized Adsorbents

Rajterowski, J., J. E. Renew, and R. Melsert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39Modular Solid-State Thermoelectric Power Generation and High-Value Lithium Recovery From Low-Temperature Geothermal Brines

Yanagisawa, N. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39Case Study of the Change of Scale With Production

Sedimentary BasinCrowell, A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Geostatistical Analysis of Bottom-Hole Temperatures in the Denver and Williston Basins: North America

Hartig, C. M. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Discrete Fracture Network Simulation for Sedimentary Enhanced Geothermal Systems: Red River Formation, Williston Basin, North Dakota

Morgan, P. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Sedimentary Basin Geothermal Resources in the Piceance Basin, Colorado

ToolsBalamir, O., W. M. Rickard, F. Wilson, K. Harestad, and P. A. Årebråt . . . . . . . . . . . . . . . . . . . . . . . . 40

Cementing Tool Supports Cement Plug in Large Diameter Geothermal Well Casing

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Brambilla, N., and F. Martini. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Ultra-High Temperature (250°C+) and Wide Operating Temperature Range Ultracapacitor Enabling Downhole Power Source for Geothermal Exploration

Erkan, K., M. Doğruel, K. Bayat, B. Akkoyunlu, M. Tayanç, E. Balkan, and S. Hamamcı . . . . . . . . . . . 41Development of a Digital Output Temperature Probe for Precision Measurements

Holbein, B., J. Isele, and L. Spatafora . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Integrated Cooling Systems for an Extended Operation Range of Borehole Tools

Kerr, R., B. D. Gleason, A. Olzick, and B. Denzel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41A New Technique and Sensor for Determining Steam Quality Along a Wellbore

Alphabetical Index of Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

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1

basin & ranGe

A Case History of the Dixie Valley Geothermal Field, 1963–2014Dick Benoit • Sustainable Solutions

Keywords: Dixie Valley, Nevada, exploration, development, case historyThe 56 MW net Dixie Valley geothermal power project has now operated at more or less full output for 27 years. This success was

primarily due to three companies with very different character and strengths being involved during the development phase between 1974 and 1988. The wide spacing of exploration wells early in the project history greatly reduced dry hole or step-out risk during the field development phase. The large horizontal and vertical separation between producers and injectors has been successful in allowing modest production fluid temperature declines. The project evolved over its initial 9 years of production from a 49.8 MW net project with a projected long-term production well makeup schedule to a 56 MW net project supported by a cold groundwater injection aug-mentation program that stabilized the reservoir pressure and eliminated the need for future makeup production wells. The timing of this fairly intense and costly activity coincided with a period of high electricity prices in the Standard Offer #4 contract that allowed significant ongoing field development expenditures. Since 2000 project improvements have shifted from the wellfield to power plant modifications. The turbine was modified to enable the power plant to operate at lower pressures and a 5 MW net binary plant was installed on the injection line.

Geothermal Potential in the Basins of East-Central and Southeastern NevadaMark Gwynn • Utah Geological Survey, Salt Lake City, UT • markgwynn@utah.gov

Keywords: Heat flow, thermal conductivity, bottom-hole temperatures, stratigraphic reservoir, permeability, Steptoe Valley Previous work has shown that several basins in northeastern Nevada have high heat flow and geothermal potential. This study

evaluates the deep thermal regime for the remainder of eastern Nevada using publicly available corrected bottom-hole temperature (BHT) and drill stem test (DST) data from past oil exploration efforts. Over 260 wells yield a dataset of nearly 500 BHTs and DSTs in a region characterized by numerous basins that typically hold about 2–4 km of low-thermal-conductivity sediments and volcanics. The basins are underlain by Paleozoic bedrock units consisting primarily of carbonates and lesser amounts of siliciclastics, some of which are known to have high permeability. Many of these units are exposed in the adjacent ranges. Such units may act as geothermal reservoirs, and due to the combination of high regional heat flow and the insulating properties of the basin fill, may host temperatures greater than 150°C beneath many basins. Results show that heat flow ranges from about 50 mW/m2 in basins within the area widely known as the Eureka Low to nearly 140 mW/m2 in Steptoe Valley at the northern end of the study area. Railroad Valley also hosts a localized area of high subsurface temperatures and heat flow, but this is the result of geothermal upflow. In the high-heat-flow basins with primarily conductive regimes, temperatures of 180°C to more than 210°C at 3–4 km depth may be expected, placing them well within the economic target of 150–200°C at 2–4 km depth for stratigraphic geothermal reservoirs. Inter- and intra-basin variations in temperature gradient and heat flow related to the effects of deep groundwater circulation appear to be present in many basins, although at least some of the variation may be the result of the notoriously low quality of BHT data.

Comparisons of Geothermal Systems in Central Nevada: Evidence for Deep Regional Geothermal Potential Based on Heat Flow, Geology, and Fluid ChemistryStefan Kirby1, Stuart Simmons2, Mark Gwynn1, Rick Allis1, and Joseph Moore2 1Utah Geological Survey, Salt Lake City, UT • 2Energy and Geoscience Institute, University of Utah, Salt Lake City, UTstefankirby@utah.gov • ssimmons@egi.utah.edu • rickallis@utah.gov • markgwynn@utah.gov • jmoore@egi.utah.gov

Keywords: Deep geothermal, Central Nevada, carbonates, heat flow, geochemistryCentral Nevada may have significant untapped deep geothermal potential. Existing geologic and heat flow data indicate the

potential for carbonate aquifers at temperatures greater than 180°C at depths below 3 kilometers. Compiled fluid chemistry from producing geothermal fields at Tuscarora and Beowawe, produced water from the Blackburn oil field, and thermal springs and wells (with temperatures greater than 30°C) all have unique and remarkably consistent major ion chemistry. Nearly all compiled samples are Na-HCO3 type water with generally low total dissolved solids and high concentrations of dissolved silica. These chemistries may result from equilibrium in warm carbonate aquifers and ion exchange and mineral precipitation as thermal fluids move toward the surface. Similarities in chemistry may result from similar thermal reservoir conditions beneath large areas of central Nevada. Simple geother-mometry yields the highest temperatures for samples from the Beowawe geothermal field. Other areas with elevated geothermometry and Na-HCO3 waters include the Tuscarora geothermal field, the Mary’s River area, and Ruby Valley. Samples from the Blackburn oilfield are similar to other thermal samples except for higher Na, Cl, and HCO3 which may result from active petroleum generation in this system. Limited stable isotope data indicate a significant geothermal signal for several samples with lower geothermometry. Similarities in heat flow and geology between central Nevada and Utah may allow for analogous geothermal conditions to exist in adjoining parts of western Utah.

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Origin and Potential Geothermal Significance of China Hat and Other Late Pleistocene Topaz Rhyolite Lava Domes of the Blackfoot Volcanic Field, SE IdahoMichael McCurry1, David M. Pearson1, John Welhan2, Shannon K. Natwotniak1, and Meghan Fisher1 1Department of Geosciences, Idaho State University, Pocatello, ID2Idaho Geological Survey, University of Idaho, Moscow, ID

Keywords: Magma-related, rhyolite, Snake River Plain, Idaho, blind geothermal systems, Quaternary tectonicsThe Snake River Plain and neighboring regions are well known for their high heat flow and robust Neogene-Quaternary tectonic

and magmatic activity. Interestingly, however, there are comparatively few surficial manifestations of geothermal activity. This study is part of a renewed examination of this region as a possible hidden or blind geothermal resource. We present an integrated conceptual model for basalts and genetically derivative topaz rhyolite lava domes of the Blackfoot Volcanic Field (BVF), linking ultimate heat and mass sources rooted in the upper mantle to potential blind geothermal systems in the upper crust. In our model in-tracrustal magma transfer and storage respond opportunistically and interactively evolving tectonic processes. Production of rhyolite magma is dominated by mantle-derived mass and heat sources. Rhyolite formation processes via fractional crystallization, cyclic remelting, mixing and assimilation occur mainly in the mid- to upper-crust, contributing to incremental assembly of an evolving magma storage and pluton system. Pre-eruption storage and phenocryst formation for China Hat occurred at ~14 km depth, and is inferred to be representative of the most evolved parts of the magmatic system. Approximately 1.2 km3 of topaz rhyolite have been erupted since 1.6 Ma and up to another 350 km3 of silicic rocks may have been intruded as hypabyssal dikes and sills at depths of 0.5 to 6 km. Average silicic magma production rate could therefore be on the order of ~1 to 200 km3/m.y. Given simple assumptions of magma genesis, eruption rates, and initial and final volatile concentrations, we infer average H2O and CO2 volatile fluxes from the rhyolite source region of ~0.1 to 10 MT/year and 10 to 1000 T/day, respectively. Lithium flux may be comparable to CO2, and it may be both an effective tracer and resource in fluids derived from the inferred consolidating China Hat magma body.

Influence of Continuously Variable Permeability and Basin Rock Properties on Three Dimensional Heat and Mass Balance Models of Basin & Range Geothermal SystemsAnn Moulding and Tom Brikowski • University of Texas at Dallas, Department of Geosciences

Keywords: TOUGH2, Basin & Range, permeability, non-magmatic, modelling, thermal conductivity, geothermal favorabilityBasin & Range (B&R) geothermal systems raise vexing heat and mass balance questions. In systems without magmatic heat

sources, observed temperatures of >200 – 280°C at depths of a few km require deep circulation of meteoric fluids in regions with steep geothermal gradients, apparently along structurally localized conduits. Previous heat and mass balance modeling studies (Moulding and Brikowski, GRC 2014) matched fluid temperatures and flow rates seen at the Dixie Valley geothermal field via a steeply plung-ing conduit (representative of a fault stepover or intersection) within a very low uniform permeability host rock (< 2 x 10-17 m2), with regional crustal heat flow of 85 mWm-2. These results also indicate that Basin and Range geothermal systems can be spatially isolated along strike of normal faults, allowing for the possibility of numerous discrete systems in geothermally active areas.

Current modeling efforts address specific rock properties that may be important factors for the development of the non-magmatic B&R geothermal systems and may help predict geothermal favorability for other sites. These properties include (1) low permeability of host rock materials which appears critical for the development of these systems (2) insulating properties of basin sediments and volcanics which may play an important role in some of the hotter systems (i.e. Dixie Valley), (3) anisotropic (layered) permeability in fluid source regions (basin sediments) which can enhance the supply of fluids for these systems, and (4) narrowing of the conduit at the surface discharge zone to limit penetration of cold surface fluids into the geothermal system, which is more consistent with observations and could explain why so many of these systems have been blind discoveries.

Comparative Analysis of Fluid Chemistry From Cove Fort, Roosevelt and Thermo: Implications for Geothermal Resources and Hydrothermal Systems on the East Edge of the Great BasinStuart Simmons1, Stefan Kirby2, Joe Moore1, Phil Wannamaker1, and Rick Allis2

1EGI, University of Utah, Salt Lake City, Utah • 2Utah Geological Survey, Salt Lake City • ssimmons@egi.utah.edu

Keywords: Geothermal resources, hydrothermal geochemistry, exploration, geology, Cove Fort, Roosevelt, Thermo, Great Basin, Sevier thermal anomaly

We assessed the thermal water compositions from Cove Fort, Roosevelt, and Thermo, and scattered hot springs to evaluate the controls on thermal water compositions within the Sevier thermal anomaly on the eastern edge of the Great Basin. The reservoir tem-peratures range from 150 to 250° C, and the reservoir rocks are diverse, including granite-gneiss, marine carbonates, and siliciclastic sequences. On the basis of major anions, the thermal waters are classified as chloride, sulfate, and hybrid chloride-sulfate type that contain variable but lower concentrations of bicarbonate. Low Mg and relatively low Cl/B further distinguish the reservoir waters at Cove Fort and Roosevelt compared to high-Mg waters with high Cl/B ratios. The oxygen and hydrogen isotopic compositions reflect the influence of local meteoric water, and the range of compositions reflect geography, recharge elevation, degree of water-rock inter-action, and possibly age. Positive correlation between helium isotope R/Ra values and reservoir temperatures indicate mantle helium and magmatic heat are associated with convective fluid flow. Application of chemical geothermometers shows that aqueous silica concentrations are the most reliable geochemical indicator of a minimum resource temperature; in low-Mg thermal waters, hot Na/K temperatures possibly reflect deep equilibration with basement crystalline rocks. Locally, heat transfer is focused along range front faults in the form of convective geothermal systems with relatively small diameter upflow zones. The large regional endowment of

3

thermal energy associated with hot basement rocks suggests there is considerable potential for finding a spectrum of blind resources including those occurring in deep sedimentary aquifers and EGS reservoirs.

Country update

The United States of America Country Update 2015Tonya L. Boyd1, Alex Sifford2, and John W. Lund1 • toni.boyd@oit.edu1Geo-Heat Center, Oregon Institute of Technology, Klamath Falls, Oregon • 2Sifford Energy Services, Neskowin, Oregon

Keywords: The Geysers, electric power, direct-use, ground-source heat pumps, energy savings, well drilled, manpower, investments

Geothermal energy is used for electric power generation and direct utilization in the United States. The present installed capacity (gross) for electric power generation is 3,477 MWe (installed) with 2,542 MWe net (running) delivering power to the gird producing approximately 16,517 GWh per year for a 74% net capacity factor. Geothermal electric power plants are located in California, Nevada, Utah and Hawaii with recent installation in Alaska, Idaho, New Mexico and Oregon, with 312 MWe being added the last five years. The two largest concentrations of plants are at The Geysers in northern California and the Imperial Valley in southern California. The Geysers continues to receive waste water from Clear Lake and Santa Rosa, California that is injected into the field and has resulted in the recovery of approximately 200 MWe of power generation. The lowest temperature installed plant is at Chena Hot Springs in Alaska, where binary cycle plants uses 74°C geothermal fluids to run three units for a total of 730 kW (gross). With the recent passing of the production tax credit by the federal government (2.0 cents/kWh) and renewable portfolio standards requiring investments in renewable energy, the annual growth rate for electric power generation over the past three years is 3.6 percent. The direct utilization of geothermal energy includes the heating of pools and spas, greenhouses and aquaculture facilities, space heating and district heat-ing, snow melting, agricultural drying, industrial applications and ground-source heat pumps. The installed capacity is 17,416 MWt and the annual energy use is 75,862 TJ or 21,074 GWh. The largest application is ground-source (geothermal) heat pumps (88% of the energy use), and the next largest direct-uses are fish farming and swimming pool heating. Direct utilization (without heat pumps) remained nearly static over the past five years with gains balancing losses; however, ground-source heat pumps are being installed at a 8% annual growth rate with 1.4 million units (12 kW size) in operation. The energy saving from all geothermal energy use is about 11.2 million tonnes of equivalent fuel oil per year (74.7 million barrels) and reduces air pollution by almost 10.0 million tonnes of carbon and 28.0 million tonnes of CO2 annually (compared to fuel oil).

Breaking Down the Barriers to Geothermal Energy in Canada: Bridging the Knowledge Gap and Overcoming the Status QuoJustin Crewson and Alison Thompson

Keywords: Canada, Site C, hot sedimentary aquifer, Yukon, policyDespite possessing significant hydrothermal resources, Canada is currently producing 0 MW of geothermal power. For anyone

following the Canadian geothermal energy industry, this is by now a disturbingly familiar narrative. The Canadian province of British Columbia (BC) and the Yukon Territory lie on the country’s west coast, which is located along the Pacific Rim. This area is dotted with around a dozen young volcanic edifices, and more than one hundred hot springs. These features provide surface evidence of “substantial high-grade geothermal power resources.” In the 1970s energy security concerns prompted the Canadian government to undertake the research and exploration of its geothermal resources. While a few promising sites were identified in BC, a subsequent calm in energy concerns led to Canada’s geothermal energy program lying largely dormant for close to two decades.

A number of factors including the increasing need for electrical imports into BC in the early 2000s, led to a significant provincial policy change that encouraged private power production. As a result, there was a renewed interest in geothermal power production in the province. Though private companies have held a number of permits over the years, and a pilot project was completed, vari-ous obstacles including significant policy hurdles prevented a power project from being completed. Amongst these hurdles are long permit wait times, erratic permit offerings, and significant levels of bureaucratic red tape. As a result, today much of the province’s geothermal potential sits idle, with many would-be developers choosing to operate internationally in what are seen to be more politi-cally permissive environments.

Worldwide Geothermal Energy Utilization 2015John W. Lund1, Ruggero Bertani2, and Tonya L. Boyd1

1Emeritus, Geo-Heat Center, Oregon Institute of Technology, Klamath Falls, Oregon2Manager, Enel Green Power, via Andrea Pisano, Pisa, Italy

Keywords: Geothermal, electricity generation, geothermal development, direct-use, spas, balneology, space heating, district heating, aquaculture, greenhouses, ground-source heat pumps, industrial applications, snow melting, energy savings, wells drilled, manpower, investment

This report presents a review of the worldwide applications of geothermal energy utilization by 2015 and updates the previous survey carried out by 2010. Both worldwide power generation and direct utilization are presented in this report. The present report is based on country update papers received from 70 countries and regions of which 24 reported electric power generation and 65 reported

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some direct utilization of geothermal energy. Seventeen additional countries were added to the list based on other sources of informa-tion. We also compare data from 1995, 2000, 2005 and 2010 presented at World Geothermal Congresses in Italy, Japan, Turkey, and Indonesia respectively (WGC95, WGC2000,WGC2005, and WGC2010).

Power plants under construction, which are expected to be commissioned in 2015, are included in the installed capacity of 12,635 MWe with an annual energy production of 73,549 GWh. An increase of 1,738 MWe in the five year term 2010-2015 has been achieved (about 16% or 3% annually), following the rough standard linear trend of approximately 350 MWe/year, with an average value of about 200 MWe/year in the preceding 2000-2005 period. The installed capacity consists of 40.2% single flash units, 22.7% dry steam units, 20.1% double flash units, 14.2% binary units, 1.4% triple flash units, and 1.4% back pressure units. Direct utilization of geothermal energy in the total of 82 countries is an increase from the 78 reported in 2010, 72 reported in 2005, 58 reported in 2000, and 28 reported in 1995. As in previous reports, an effort is made to quantify ground-source (geothermal) heat pump data which has grown at an annual rate of 8.6% in installed capacity and 10.2% in annual energy use over the past five years.

An estimation of the installed thermal power for direct utilization by 2015 equals 70,329 MWt, almost a 45% increase over the 2010 data, growing at a compound rate of 7.7% annually with a capacity factor of 0.265. The thermal energy used is 587,786 TJ/yr (163,287 GWh/yr), a 38.7% increase over 2010, growing at a compound rate of 6.8% annually. The distribution of thermal energy used by category is approximately 55.3% for ground-source heat pumps, 20.3% for bathing and swimming (including balneology), 15.0% for space heating (of which 89% is for district heating), 4.5% for greenhouses and open ground heating, 2.0% for aquaculture pond and raceway heating, 1.8% for industrial process heating, 0.4% for snow melting and cooling, 0.4% for agricultural drying, and 0.3% for other uses.

For electric power generation and direct utilization combined, the energy savings amounted to 474 million barrels (71.5 million tonnes) of equivalent oil annually, preventing 74.4 million tonnes of carbon and 194.4 million tonnes of CO2 being released to the at-mosphere, this includes savings for geothermal heat pumps in the cooling mode. Approximately 2,218 well were drilled in 42 countries, 34,000 person-years of effort were allocated in 52 countries, and US$20 billion invested in projects by 49 countries.

Revisiting the Assessment of Geothermal Resources <90 °C in the United StatesColin F. Williams, Jacob DeAngelo, and Marshall J. Reed* • U.S. Geological Survey, Menlo Park CA • *deceased

Keywords: Assessment, direct use, electric power, temperature gradient, geothermometerIn 2008 the US Geological Survey (USGS) updated the 1979 assessment of the electric power generating potential of geothermal

resources in the United States associated with natural hydrothermal systems. These resources are concentrated in the states of Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming, which contain all 248 identified hydrothermal systems located on private or accessible public lands and with temperatures greater than 90 ºC in the US outside of Alaska and greater than 75 ºC in Alaska that have the potential to be exploited for electric power generation. The estimated mean electric power generation potential from identified geothermal resources in the 2008 assessment is approximately 9060 MW-electric (MWe). Of this total approximately 1640 MWe is from systems which fall in the temperature range greater than 90 ºC and less than 150 ºC. The USGS is completing an updated evaluation of geothermal resources with temperatures less than 90 ºC in order to provide a comprehensive look at conventional geothermal resources across the entire temperature range. In this work the estimate of total beneficial heat for these systems is 46,500 MWth, with a total wellhead thermal energy of 94x1018 J. A potential electric power generating capacity of approximately 400 MWe could be associated with systems in the temperature range 50 to 90 ºC, a modest addition to the 9060 MWe estimated for higher temperature systems but one which may have significance in meeting certain local power needs, particularly in remote areas.

direCt use

Accelerated Plant Growth Results From an Intensive Shallow Bottom Heat System Using Waste Geothermal Hot Water and Steam Condensate in IcelandRobert Dell1, Runar Unnthorsson2, C. S. Wei3, and William Foley1 1Center for Innovation and Applied Technology, Mechanical Engineering, The Cooper Union, NY, USA2Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, University of Iceland, Reykjavik, Iceland 3Mechanical Engineering, The Cooper Union, NY, USA

Keywords: Geothermal agriculture, heated soil, heated ground agriculture, cascade utilization, enhanced growing season, waste heat, global warming

The authors have developed an enhanced intensive shallow bottom heat agricultural system using waste geothermal hot water and steam condensate that is analogous to a heated sidewalk at the Agricultural University of Iceland, the Keilir Institute of technology and HNLFI clinic in Iceland. The gardens are heated throughout the year. The results confirm the survival of out of zone plants, including tomatoes and zucchinis that produced a harvestable crop. Plant growth was often increased by 20% or more while the growing season was extended by about 4 to 6 weeks that may increase the value of the crop. Green grass has been documented during the winter. The authors have developed an analogous system in New York City using waste CHP heat in a similar cascade utilization that has demonstrated comparable results.

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Heat Exchange Rate Enhancement in Ground Heat Exchangers by Water Injection and PumpingHadi Farabi Asl, Hikari Fujii, and Hiroyuki KosukegawaFaculty of International Resource Sciences, Akita University, Akita, Japan

Keywords: Geothermal heat pump, ground heat exchanger, thermal response test, water injection, water pumping, sensitivity analysis

One of the most effective development barriers of Geothermal Heat Pump (GHP) systems is the high initial cost in comparison with customary heating and cooling systems. By increasing the heat exchange capability of Ground Heat Exchangers (GHE), the needed length of GHE for assigned thermal load is reduced and as a result, the initial cost of system decreases.

In a ground with groundwater flow, the forced convection mechanism improves the heat exchange rate between ground and GHE. In low groundwater flow areas, we can cause an artificial groundwater flow around the GHE by injecting or pumping water inside the GHE. This method can be efficient in low thermal conductivity (λ) areas.

In this study, 9 sets of Thermal Response Tests (TRT) were performed with different rates of water injection or pumping and dif-ferent injecting water temperature on a GHE on the campus of Akita University, Akita, Japan. The GHE was modeled by FEFLOW 6.2 software and outlet water temperature and ground temperature recovery was validated by the TRT data. Then, sensitivity analysis were carried out to investigate the effects of injecting or pumping with different water rates (0-15 L/min) and different inlet water temperatures (0 and 5 °C) and also different groundwater velocities (0 and 0.1 m/day). Results of experiments and simulations showed that heat exchange rate between ground and GHE increases significantly by applying water injection or pumping inside the GHE, but for the rates higher than 5 L/min, heat exchange rate is less affected by increasing the water rate.

Point of Use Thermoelectric Powered Automated Irrigation System for an Intesive Shallow Bottom Heat System Using Waste Geothermal Hot Water and Steam Condensate in IcelandWilliam Foley1, Robert Dell1, C. S. Wei3, and Runar Unnthorsson2

1Center for Innovation and Applied Technology, Mechanical Engineering, The Cooper Union, NY, USA2Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, University of Iceland, Reykjavik, Iceland3Mechanical Engineering, The Cooper Union, NY, USA

Keywords: Waste hot water, irrigation system, automation, heated ground agriculture, geothermal heated soil, cascade utilization

In Iceland there is a super abundance of waste hot water from geothermal power plants at a temperature between 130-160°C. Some of this is re-purposed to heat cold water and is used for district heating and heated swimming pools. This waste energy source has also enabled the growth of out of zone plants, enhanced agricultural production by 20%, and extended the growing season by using the authors’ energy intensive shallow system of bottom heat that incorporates existing heated sidewalk technology.

Complete autonomy of the field tested heated garden system is not possible without an independent, sustainably powered irriga-tion control system. Long term plant studies on the plant growth have been limited due to the lack of scheduled and reliable watering cycle as plants die during the growing season. The authors have also designed and constructed an automated thermoelectric powered irrigation system that was developed for the maximum plant growth of the Icelandic heated gardens. It has a subsystem that records soil moisture and ambient temperature. When the soil is too dry it is irrigated by opening a valve connected to a municipal water line. An identical irrigation system is currently in use for the author’s heated green roof experiments at The Cooper Union in New York City that uses waste heat from a Combined Heat and Power (CHP) system as the heat source. The system allows for long term maximum growth experiments while increasing the system’s sustainability.

Use of Waste Heat From Geothermal Power Plants Focusing on Improving Agriculture in Developing CountriesMagnus Gehringer, M.Sc. • Consent Energy LLC, Washington DC • www.consentenergy.com

Keywords: Waste heat, cascaded use, CHP, agriculture, cooling, technologies, economics, benefits, regulations, PPAThe concept of this paper is to make geothermal power producers and country governments think about the tremendous value in

waste heat from power generation. Globally, several countries with high or medium temperature resources plan to build new geothermal power plants. Based on re-

source temperatures of around or over 250°C, they will be “flash” plants and convert energy from 250 down to 150°C into electricity. This will make a lot of waste heat accessible. This paper provides indicative estimates of the amount of waste heat available from a typical 50 MWe flash plant and how this waste heat of around 100 MWth could be used.

The findings are that a 50 MWe power plant could provide waste heat to operate: – A 5 to 10 MWe binary plant to generate additional power, – A 100,000 m2 freezing and cooling plant, the size of 14 football fields, – A canning factory producing 200 tons per hour and filling 100 containers per day, or – A fruit drying plant producing 50 tons per hour and filling 25 containers per day.

Overall, the paper shows that revenue creation from waste heat use could be several times the revenues from power generation. At the same time, the use of waste heat supports regional development through job creation and new agricultural opportunities, e.g. through marketing of new products. Finally, this would imply additional tax revenues to the country, increased value of food products and potential new export products.

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Geothermal Direct Utilization-Design and OptimizationSaeid Jalilinasrabady • Faculty of International Resource Sciences, Akita University, Japan • jalili@gipc.akita-u.ac.jp

Keywords: Geothermal direct uses, district heating, swimming pool, MatlabThe Sabalan geothermal area in northwest of Iran is potentially an important place for tourism in Iran. After realizing the plans for

building the first geothermal electric power plant in this region and developing swimming pools, using the geothermal water available in this area, hopefully it will be more attractive for tourists and also provide good sanitation facilities for the local people. According to calculations described in the paper, Gheynarjeh hot spring has been found to be suitable as a heat source for a swimming pool, both with regard to the required temperature and flow rate. The paper also describes the design of a district heating system for Moeil village. The heat load for one sample building was calculated. Comparison of mass flow for a geothermal and fuel-fired system was done, and the influence of radiator size on indoor temperature was analyzed based on a steady-state model. In addition to this, a district heating network was designed and calculations done for it. The simulation results are reasonable and provide a good starting point for a real project.

Evolution of Balçova Geothermal District Heating System — TurkeyMahmut Parlaktuna • Middle East Technical University, Department of Petroleum and Natural Gas Engineering, Ankara, Turkey • mahmut@metu.edu.tr

Keywords: Balçova geothermal, district heating, Agamemnon Fault Balçova geothermal field is located in a densely populated area which makes direct heat applications very efficient and economi-

cal. Heat produced from Balçova geothermal field is utilized for three main purposes: greenhouse heating, balneology and residential heating. Among these three applications, the latter one is the main application throughout the Balçova Geothermal District Heating System (BGDHS). The field produces hot water from two different horizons: one shallow and one deeper zone. This paper presents the encountered problems and their solution strategies while expanding the system to the current state of 35,000 residence equivalent capacity (1residence equivalent = 100 m2 heated area).

The Lindal Diagram for Mining EngineeringEleni Patsa1*, Sadiq J. Zarrouk2, and Dirk Van Zyl1 • *lena@mining.ubc.ca1N.B.K. Institute of Mining Engineering, University of British Columbia, B. C., Canada2Department of Engineering Science, University of Auckland, Auckland, New Zealand

Keywords: Geothermal direct use, Lindal diagram, mining, mineral processing, mines, geothermal energy, opportunities, energy options

The Lindal diagram is an effective way to illustrate the various applications of geothermal fluids, in terms of resource temperature. Its current version includes a wide range of well-established, albeit generic, applications that are not specific to a particular sector or industry. Mining operations have variable energy needs, and for some mines, geothermal energy can be a viable option for heat min-ing and/or on-site power production. Although proven as a technology, engineers and other mining professionals are not always fully aware of the ways that geothermal energy can be put to use within the context of a mining operation. The mining-specific version of the Lindal diagram presented herein addresses this gap. It has been redrawn to exclude any potential application that does not apply to the mining industry, while at the same time adding those that are.

Design of a Cooling System Using Geothermal Energy for Storage of Agricultural Products With Emphasis on Irish Potatoes in Rwanda, AfricaJane Uwera1, Ryuichi Itoi1, Saeid Jalilinasrabady2, Thirleikur Jóhannesson3, and Davíð Örn Benediktsson3 1Department of Earth Resource Engineering, Faculty of Engineering, Kyushu University, Fukuoka, Japan2Faculty of International Resource Sciences, Akita University, Akita, Japan • 3Verkis, Icelandkamanzijn@gmail.com • itoi@mine.kyushu-u.ac.jp • jalili@gipc.akita-u.ac.jp

Keywords: Energy, energy rate, coefficient of performance, refrigeration, potatoes, Karisimbi, RwandaThis study focuses on the design of a cooling system for storage of agricultural products. An absorption refrigeration unit which

uses a geothermal heat source to drive the absorption cycle in a chilling process, in a 25°C environment with a compartment tempera-ture of 5°C. This system is to provide the cooling to the cold storage with a heat load of 140 kWt. The parameters mainly monitored are COP, heat transfer rates, mass flow of a geothermal fluid and the power required to run the cycle. Thermodynamic analysis of the cycle concluded that the COP of the absorption refrigeration cycle is 0.49, but can go as high as 0.6 when a heat exchanger is used.

Study of Thermal Performance and Operation Strategy of a Compound Ground Source Heat Pump Heating SystemZhang Wei1,2 , Junxin Lv1,2, and Liu Jiulong3 1Key Laboratory of Efficient Utilization of Low and Medium Grade Energy, MOE, Tianjin University2Geothermal Research &Training Center, Tianjin University, Tianjin, China3Tianjin Geothermal Exploration and Development-Designing Institute, Tianjin, China

Keywords: Ground source heat pump (GSHP) system, composite power system, heat-storage tank, economic analysis, coefficient of performance

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The ground-source heat-pump (GSHP) system is being more and more attractive for air conditioning because of the high energy efficiency and reliable operation stability. Air conditioning energy consumption accounting for the proportion of the national total energy consumption increases gradually, which has reached 22.75%. Thus energy conservation and research in the field of Heating Ventilation Air Conditioning(HVAC) has become one of the key research direction of energy saving and emission reduction. This paper presents thermal performance and economic analysis of a composite power system in the heating season which consists of a GSHP system and a heat storage tank. We built an engineering project and simulated the system condition by TRNSYS and found that the coefficient of performance (COP) of the composite system is about 0.2 higher than a GSHP system, and it will save 8.96% of electricity. As a result of different electricity price in Tianjin, this system costs 25.3% less than GSHP systems

drillinG

Optimizing Geothermal Drilling: Oil and Gas Technology TransferKate Denninger1, Alfred Eustes1, Charles Visser2, Walt Baker1, Dan Bolton1, Jason Bell1, Sean Bell1, Amelia Jacobs1, Uneshddarann Nagandran1, Mitch Tilley1, and Ralph Quick1 1Colorado School of Mines • 2National Renewable Energy Laboratory • aeustes@mines.edu • charles.visser@NREL.gov

Keywords: Drilling, oil and gas, the perfect well, rig management, mechanical specific energy, performance qualifiers, lost circulation, geothermal well cementing

There is a significant amount of financial risk associated with geothermal drilling. This study of drilling operations seeks opportuni-ties to improve upon current practices and technologies. The scope of this study included analyzing 21 geothermal wells and 21 oil and gas wells. The goal was to determine a “Perfect Well” using historical data to compare the best oil and gas well to the best geothermal well. Unfortunately, limitations encountered in the study included missing data (bit records, mud information, etc.) and poor data collection practices An online software database was used to format drilling data to IADC coded daily drilling reports and generate figures for analysis. Six major issues have been found in geothermal drilling operations. These problems include lost circulation, rig/equipment selection, cementing, penetration rate, drilling program, and time management. As a result of these issues, geothermal drill-ing averaged 56.4 days longer than drilling comparable oil and gas wells in the wells in this study. Roughly $13.9 million was spent on non-productive time in the 21 geothermal wells, compared with only $1.3 million in the oil and gas wells, assuming a cost of $50,000 per day. Comparable events such as drilling the same sized hole, tripping in/out, cementing, and running the same size casing took substantially less time in the oil and gas wells. Geothermal wells were drilled using older and/or less advanced technology to depths less than 10,000 feet, while oil and gas wells reached 12,500 feet faster with purpose built rigs. A new approach is now underway that will optimize drilling programs throughout the drilling industry using Mechanical Specific Energy (MSE) as a tool to realize efficient drilling processes. Potential improvements for current geothermal operations are: the use of electronic records, real time services, and official glossary terms to describe rig operations, and advanced drilling rigs/technology.

Comparison of Drilling Technologies Between Top Drive and Rotary Table in Geothermal Fields: A Case Study of Olkaria Geothermal FieldsJames Kahutu and Victor Atwa * Kenya Electricity Generating Company Limited, Geothermal Resource Development, Naivasha, Kenya • jkahutu@kengen.co.ke • vicatwa@kengen.co.ke

Keywords: ROP- Rate of Penetration, stands, singles, stuck pipes, top drive, rotary table, drilling efficiency, weight on bit (WOB), tripping

Due to accelerated drilling in the geothermal fields, there is need to adopt better drilling technologies to reduce drilling time for the well, drilling down time and increase equipment life time. One of the technologies adopted is the utilization of a top drive compared to a rotary table. A rotary table is a mechanical device on a drilling rig that provides clockwise (as viewed from above) rotational force to the drill string to facilitate the process of drilling a bore while the top drive is a motor that is suspended from the derrick, or mast of the rig to facilitate the rotation of the drill string. The aim of this paper is to compare the drilling efficiency between top drive and rotary table in terms of rate of penetration, ability to manage stuck pipe and general safety during the drilling processes. The paper will use the case study of Olkaria geothermal field whereby both the top drive and rotary table have been used to drill geothermal wells.

Challenges of Cementing Olkaria Geothermal FieldNahashon Karanja • KenGen Olkaria Geothermal Projects, Naivasha • nnzioka@kengen.co.ke

Keywords: Thickening time, ECD (equivalent circulating density), Bearden Consistency, BHCT (bottom hole circulating temperature), WOC (wait on cement), lead cement, tail cement, scavange

Olkaria Geothermal field poses major challenges in cementing of well casings due to the fact that the area is highly permeable, the down hole temperature and pressure is very high and the cement sheath between the annular and casing is prone to carbonation which leads to strength retrogression. This paper documents the analysis of cement consumption per region in the entire Olkaria field to emphasis on the problem of permeable formations and various measures taken to improve on cement slurry design and cementing practices to handle this problem. A case study of cementing a high pressure well, #OW-724V is presented. Current cement design to handle high temperature and high pressure systems is also presented. Attempts to fight these challenges have been met with varying levels of success so suggested improvements to the current cement design and practices is also presented.

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Well Design and Well Workover to Land Deep Production Casings in the Menengai Field Abraham W. Khaemba • Nakuru, Kenya • akhaemba@gdc.co.ke

Keywords: Production casings, cement slurry, cold flow, external casing packer, tie back casing, cemented linerDrilling has been on going at Menengai high temperature field since 2011. The wells are regular well design wells with the 20″

surface casing set at 60-70m. 13⅜″ anchor casing set at about 400m depth and the 9⅝″ production casing set at between 800-1400m. The wells are targeted to be drilled to a total depth of 2500-3000m, with the slotted 7″ liners run to the bottom. All the casings used are grade K55 with threaded couplings.

Data from offset wells drilled earlier have helped design the depth of the production casing to avoid cold inflows into the wells. Wells located at the center of the field which are at a higher elevation have the production casings set at about 850m, while wells sited further away, the production casing has been designed to be set further deeper, to up to 1400m.

A majority of the wells at the Menengai field have the production casing set at 1400m. This paper looks at designing wells with 9⅝″ K55 production casing, slurry design and the most effective method for cementing the casing to ensure an effective cement job. Cementing methods that will be discussed include cementing head and plugs, two stage cementing, C-Flex RPL from peak using the inner string method, reverse circulation cementing with inner string and flap gate valve collar and use of foam cementing.

The paper looks at a number of wells which have already been completed. Pressure and temperature logs of the wells are analyzed as well as the borehole geology to identify the cold inflow zones. The remedial mechanisms available for sealing off the cold zones in completed wells are then researched and the most effective method to be applied at the Menengai field identified. The methods include use of External casing packer (ECP) and tie back design.

Modelling of Geothermal Drilling Parameters — A Case Study of Well MW-17 in Menengai KenyaThomas Miyora, Magnús Þór Jónsson, and Sverrir Þórhallssonmiyorato@yahoo.com • magnusj@hi.is • Sverrir.Thorhallsson@isor.is

Keywords: Modelling, drilling parameters, model theory, measured and modeled parameters, multiple linear regressionSeveral factors come into play when a drill bit is crushing the rock at the bottom of the hole. To effectively drill geothermal wells,

these factors must be carefully considered and combined in an optimum manner. The characteristic of geothermal formations is such that it is composed of different layers of rocks alternating from the surface to the final depth. Some rocks are highly temperature altered while others are highly fractured and unconsolidated. A careful approach has to be devised while drilling through the different sections to avoid problems which lead to delays in drilling. At the same time drilling parameters have to be applied according to the rock types in such a way that the well is drilled in the shortest time possible and in the most cost effective manner. The following factors have been mathematically modelled by Multiple Linear Regression and shown how they affect the overall drilling rate: Formation strength, Depth, Formation compaction, Pressure differential, Bit diameter and Weight on bit (WOB), Bit rotation (RPM), and Bit hydraulics. This modelling approach has been adapted for geothermal drilling from the Oil and Gas drilling as first applied by Bourgoyne and Young. Data captured while drilling of well MW-17 in Menengai geothermal field was used in making the drilling model. A combina-tion of Excel and Matlab was used in the data analysis.

Use of Carbon Microfibers for Reinforcement of Calcium Aluminate-Class F Fly Ash Cement Activated With Sodium Meta-Silicate at up to 300°CTatiana Pyatina and Toshifumi SugamaBrookhaven National Laboratory, Sustainable Energy Technologies Department, Upton, NY

Keywords: EGS, calcium-aluminate cement, fiber reinforcement, fly ash, sodium metasilicate, toughnessThis study assessed the carbon microfiber (CMF) for improvement of the compressive-toughness and steel-cement shear bond

strength of sodium metasilicate-activated calcium aluminate/Class F fly ash foamed cement at hydrothermal temperatures of up to 300°C. In contact with cement pore solution the CMFs surfaces undergo alkali-caused oxidation, leading to the formation of metal (Na, Ca, Al)-complexed carboxylate groups. The extent of this oxidation is higher at higher temperature where the fibers incorporate more oxidation derivatives, such as complexed carboxylate groups, which play a pivotal role in improving the adherence of fibers to the cement matrix. Such fiber/cement interfacial bonds contributed significantly to the excellent bridging effect of fibers, resistance to the cracks development and propagation, and to improvement of the post-crack material ductility. Consequently, the compressive toughness of the 85°-, 200°-, and 300°C-autoclaved foamed cements reinforced with 10 wt.% CMF was 2.4-, 2.9-, and 3.1-fold higher than for cement without the reinforcement. Additionally, the fibers not only increased steel-cement shear bond strength but more importantly significantly improved the resistance of this bond to a thermal shock (350°C heat followed by 25°C water cooling) allowing only 35% decrease in it after 7 thermal shock cycles vs. 64% strength decrease in the bond strength without fiber reinforcement.

Broaching: An Effective Method of Well Intervention for Calcite Scale RemovalDaniel Robert Wilson1, John Gilliland2, and Andrew Austin2 1Contact Energy, Wairakei Geothermal PowerStation, Taupo, NZ • 2JRG Energy Consultants Ltd, Taupo, NZdaniel.wilson@contactenergy.co.nz • john@jrgenergy.com • andrew@jrgenergy.com

Keywords: Geothermal, broaching, slickline, wireline, well intervention, calcite scale, well workover, contact energy, Western Energy Services, JRG Energy

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Calcite scaling is the leading cause of production loss in Geothermal wells. The most common well intervention technique to combat the issue of scaling is a drilling rig workover. The average cost of well workovers has increased considerably in the last 5-10 years, resulting in an economical conflict to workover certain wells. In 2013 Contact Energy (CEL, Operator) and Western Energy Services (WES, Service Company) researched, developed, trialled and implemented a wireline intervention technique and methodology to successfully remove and reduce calcite scale in the Ohaaki and Wairakei geothermal fields in New Zealand. This wireline intervention technique, called broaching, is a process developed in the oil and gas industry which uses mechanical tools to remove mainly silica from small diameter production tubing. This process has been transformed to accommodate the geothermal industry by designing tools to combat large volumes of calcite in larger diameter casings.

Contact and Western Energy have successfully utilised Broaching to workover 10 geothermal wells regaining over 28MW of production for less than 50% of a single traditional well workover. Perhaps the largest benefit of broaching is that the wells targeted would have been uneconomical or unfeasible to work over using a rig. Broaching has allowed wells that have been dormant for years to contribute to electricity generation. Contact, Western Energy, and JRG Energy are continuously analysing empirical data from previ-ous broaching jobs to improve tool development, operations, and broaden the available window where broaching can be an effective method of geothermal well maintenance. Tool technology, well conditions, wireline experience, and calcite conditions are some of the many outlying variables determining broaching success.

east afriCan rift

Characterization of Quaternary Extensional Structures: Tulu-Moye Geothermal Prospect, EthiopiaEngdawork Admassu1 and Selamawit Worku2 1Geological Survey of Ethiopia, Addis Ababa, Ethiopia2United Nations University, Geothermal Training Programme, Orkustofnun, Reykjavik, Iceland engaye@gmail.com • soliethio@yahoo.com

Keywords: Main Ethiopian Rift, Tulu-Moye, geothermal, magmatic segment, faulting, morphologyThe area of investigation, Tulu-Moye, is situated in the Main Ethiopian Rift (MER) northwest of Asela close to the eastern margin

of the rift. It is a wide zone where tectonic and volcanic activities are concentrated. As a major part of the Koka magmatic segment, The Tulu-Moye area has depicted interesting characteristics of volcanism and geologic structural patterns. The formation and growth of faults in the area could be explained by three progressive phases of faulting. Two fault models are proposed to explain the sequence of faulting, fracturing and lava flow events. The volcanic activities of the area are mostly controlled by the active faults and extension fractures of the Wonji Fault Belt (WFB). A fault morphology survey exhibited the various nature of the fault and fissure morphology that was primarily controlled by strike variations in the geologic units. The fault kinematic data collected from selected localities indicated E-W direction (~ 930) extension, consistent with previous works conducted in other parts of the MER.

A comprehensive relationship between Quaternary faulting and magmatism was realized in the Tulu-Moye geothermal prospect. In such a way that, cone-fault, cone-lava and lava-fault interactions were the most noticeable relationships between Quaternary faulting and magmatism in the area. The fault morphology, fault model, fault-magmatism relationships, suggests a progressive development of an extension fissure to a mature normal fault. Tulu-Moye has both favorable geological and structural features for a prospective geothermal resource, which however deserves detail geothermal investigations towards defining the area’s major parameters.

Stakeholder Engagement Through Participatory Research: A Case Study of Eburru Geothermal Wellhead Generator in Nakuru County, KenyaPhilip J. Barasa and Rose W. Mathenge • Olkaria Geothermal Project • pbaraza@kengen.co.ke • rmathenge@kengen.co.ke

Keywords: Stakeholder engagement, Environmental & Social Impact Assessment, wellhead, participatory research, communityStakeholder engagement should be at the heart of any “sustainable development” agenda. Engaging with stakeholders is acknowl-

edging that a business is an interdependent entity, which is impacted by and has an impact on many different groups. Stakeholder engagement can hence be used as a means to improve communications, obtain wider community support or buy-in for projects, gather useful data and ideas enhance public sector or corporate reputation, and provide for more sustainable decision-making. Stakeholder engagement has recently been increasingly identified as key to business success both within private and government sectors. This paper highlights how Kenya Electricity Generating Company Limited (KenGen) has effectively engaged stakeholders at Eburru Geothermal Field located in Gilgil Subcounty, Nakuru County in Kenya. Emphasis will be placed on how stakeholders concerns, regarding operation of a 2.4MW wellhead power plant, are being addressed through participatory research involving KenGen, local community members and Ministry of Agriculture and Livestock (MAL). In the research, farmers were involved from the conceptualization, planning, execution, data collection and monitoring of the research parameters. This was geared to ensure that the research findings were socially accepted.

During the research roll out, a number of challenges were encountered, namely social unrest and historical mistrust between the community and the Government bodies. These challenges were largely surmounted and the research progressed as envisaged. So far, the benefits accrued by KenGen include minimal negative publicity by the public in regard to the company operations in Eburru area. Second, gradually the community has gained trust in KenGen. On the part of community, the benefits include training of farmers on best agronomic practices mainly in terms of fertilizer application, disease control and use of certified seeds. Second, some farmers have adopted some of the new crops advocated by the MAL because the research confirmed that they are suitable for the area. Third,

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farmers embraced the recommended type of fertilizer as opposed to the type of the fertilizers they were previously using which had resulted in their soil being acidic as per the soil baseline analysis findings. KenGen met the full cost of carrying out the research.

The Western Branch of the East African Rift: A Review of Tectonics, Volcanology and Geothermal ActivityBjörn S. Harðarson • Iceland GeoSurvey (ISOR), Reykjavik, Iceland • bjorn.s.hardarson@isor.is

Keywords: East African Rift System, West African Rift, tectonics, volcanology, geothermal activity, mantle plumes, igneous geochemistry, geothermal prospects

The East African Rift System (EARS) is a classic example of continental rifting and provides an excellent framework to study extensional magmatism and the evolution of several central volcanic systems that have formed along the rift from the Tertiary to Recent. Many of the volcanic structures have developed substantial high-temperature geothermal systems where the heat source is magmatic and related to central volcanoes. Detailed studies indicate that the geothermal potential in Eastern Africa is in the excess of 15,000 MWe. However, despite the high geothermal potential of EARS only Kenya has installed significant capacity of about 570 MW. Magmatism along the EARS is generally believed to be associated with mantle plume activities but the number and nature of mantle plumes is still, however, controversial. EARS is divided into two main branches, the Eastern- and Western rifts, and it is well documented that significantly greater volcanism is observed in the older Eastern rift (i.e. Ethiopia and Kenya) compared to that in the younger Western rift, where eruptive activity is, in general, restricted to four spatially distinct provinces along the rift axis. These are the Toro-Ankole in western Uganda, the Virunga and Kivu provinces along the border of the DRC with Uganda, Rwanda and Burundi, and the Rungwe volcanic field in SW Tanzania.

Evolution and Geology of Eburru-Badlands Geothermal Prospect — Central Kenyan RiftIrene Ronoh • Kenya Electricity Generating Company (KenGen) • ironoh@kengen.co.ke

Keywords: Exploration, geology, Eburru-Badlands, Scanning Electron Microprobe, classification, bulk rock chemistry, peralkaline, subalkaline, evolution

Eburru-Badlands Geothermal Field is characterized by Trachyte, Pantellerites, Basalts and Pyroclastics. The lavas are classified into pre- and post- faulting events estimated to be aged between 1.2 Ma and 100 years BP. The older formations are affected by a major faulting event dated between 0.8 Ma and 0.4 Ma (Clarke et al., 1990). The younger lavas include Trachyte (Et2), basalt (Eb2), Pyroclastic (Ep2) and Pantellerite (Ep2). They are not faulted and occur along the younger N-S faults. Thirteen rock samples from surface outcrops were analyzed and identified as Trachyte (Et1), Trachyte (Et2), Basalt (Eb2), Pyroclastic (Ep2) and Pantellerite (Ep2). The Trachyte (Et1) is folded and fractured, and hence belongs to the pre-faulting stratigraphic sequences. The rocks are porphyritic with quartz, sanidine, pyroxenes, amphiboles, plagioclase and olivine of varying amounts. Classification of these rock units indicates that SiO2 weight percent increases from basalts (45-50%) through Trachyte (65%) and Pantellerites (69-74%) to Pyroclastics (78%). The Pyroclastic rocks (Ep2) are mainly obsidian flows which are devitrified and appear brecciated. High (Na2O+K2O) weight percent content in Trachytes and Pantellerites makes them strongly peralkaline. The silicic rocks are characterized by low Al2O3 and Fe2O3. Basalts are associated with an increase in Al2O3 and with a decrease in SiO2. Analyzed basaltic and Pyroclastics samples are subalkaline.

Geochemical models of basalts and silicic peralkaline lavas show that the magmas are ultimately mantle-derived and that the evolution was dominated by fractional crystallization processes. This classification shows an evolution trend from basalts through Trachyte to Pantellerite.

The Initial-State Geochemistry as a Baseline for Geochemical Monitoring at Olkaria Domes, KenyaRuth Wamalwa • Olkaria • Wamalwarn2000@gmail.com

Keywords: Baseline chemistry, geochemical monitoring, early phase of productionOlkaria IV power plant was commissioned in October, 2014 and has been operated since then with an installed capacity of 140MW.

As a reference in the geochemical production monitoring activities, a baseline is hereby made by using chemical data from thirteen active production wells that is collected during the discharge test. It is expected that this will assist in monitoring the changes in the chemical fluid composition from the production wells in response to fluid extraction from the reservoir as well as the response of brine and condensate reinjection into the reservoir. With that, the relationship between the enthalpy-chloride, the chloride distribution, the distribution of silica (SiO2), the total non-condensable gases (TNCG) distribution, the sulfate distribution and the temperature distribution was made to see the condition of the geochemistry reservoir in the early phase of production and as a baseline monitoring program planned in the exploitation phase.

The results, basing on the Cl content, SiO2 content and temperature distribution give an overview of the hydrology of the Olkaria Domes field where the hot fluid are encountered in OW-915, OW-915A, OW-915B and OW-916. Wells OW-910, OW-908, OW-908A and OW-908B have low ratio of chloride to sulfate concentration. This region also coincides with areas with high CO2 concentration and N2 gas values. This is a case of immature fluids being discharged. Enthalpy-Cl diagram shows the mixing process of the wells with steam heated waters.

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enhanCed Geothermal systems (eGs)Hydraulic and Thermal Stimulation Program at Raft River Idaho, A DOE EGSJacob Bradford1, John McLennan1, Joseph Moore2, Robert Podgorney3, and Shashank Tiwari1 1Department of Chemical Engineering, University of Utah, Salt Lake City UT, USA2Energy & Geoscience Institute at the University of Utah, Salt Lake City UT, USA3Idaho National Laboratory, Idaho Falls ID, USA

Keywords: Enhanced geothermal system, FALCON, hydraulic stimulation, Raft River, reservoir simulation, thermal stimulationA Department of Energy Enhanced Geothermal System (EGS) stimulation program has injected over 254 million gallons of water

into the well RRG-9 ST1 since the summer of 2013. Three major stimulations have been conducted during the program increasing injection flow rates from less than 20 gpm to 550 gpm. Geologic, water chemistry, microseismic activity, and borehole imaging data have been used to develop a conceptual model describing possible flow paths of this injected water. This model contains two major fracture zones one of which intersects the RRG-9 ST1 wellbore. Modified Hall and injectivity index plots constructed using injection flow rates, surface temperatures, and wellhead pressures show steady improvement in the injectivity of the well. The injectivity index has risen from 0.15 gpm/psi to 2.0 gpm/psi. A pressure falloff test conducted on April 28, 2015 indicates a reservoir permeability of 1,220 md and -5.38 skin factor. The well stimulation program was simulated numerically using an Idaho National Laboratory reservoir simulation code, FALCON. These simulations show a significant increase in the permeability of connecting fracture pathways after each stimulation event.

Production Well Targeting at Newberry Volcano EGS DemonstrationTrenton T. Cladouhos, Matthew E. Uddenberg, Michael W. Swyer, Susan Petty, and Yini Nordin AltaRock Energy, Inc., Seattle WA • tcladouhos@altarockenergy.com

Keywords: EGS, enhanced geothermal system, Newberry, stimulation, microseismicity, hydroshearingThe Newberry Volcano EGS Demonstration is a five year field project designed to demonstrate recent technological advances for

engineered geothermal systems (EGS) development. Advances in reservoir stimulation, diverter, and monitoring are being tested in a hot (>300 ºC), dry well (NWG 55-29) drilled in 2008. In the fall of 2014, 9,500 m3 (2.5 million gallons) of groundwater were injected at a maximum wellhead pressure of 195 bar (2850 psi) over 4 weeks of hydraulic stimulation. Injectivity changes, thermal profiles and seismicity indicate that fracture permeability in well NWG 55-29 was enhanced. The fifteen-station microseismic array (MSA) located 398 seismic events, ranging in magnitude from M 0 to M 2.26. The next step is to drill a production well into the EGS reservoir. Advanced analysis of the microseismic data including hand picking of first arrivals, moment tensors derivations, relative relocations, and velocity model improvements have resulted in new higher-quality microseismic catalogs. These catalogs have been combined by relative weighting and gridding of seismic densities, resulting in probability-based maps and cross-sections, which have been used to plan a production well trajectory. The microseismic locations and times were also used to develop a reservoir diffusivity model, which can be used to evaluate stimulation plans such as dual-well stimulation.

Analysis of Seismic Moment Tensor, Finite-Source Scaling and Fluid Imaging During EGS Resource Development at The Geysers, CADouglas S. Dreger1, Roland Gritto2, and O. Sierra Boyd1 1Berkeley Seismological Laboratory • 2Array Information Technology

Keywords: The Geysers, EGS development, fracture characterization, subsurface fluid distribution, induced seismicity, seismic analysis

In this paper, we investigate seismicity in the vicinity of the EGS development at The Geysers Pratti-32 injection well. For this investigation we have incorporated the capability of simultaneously inverting full waveform data and body wave amplitude ratios to improve estimates of the source mechanism of small events. We have analyzed the full moment tensor and finite-source models of five Geysers events ranging in magnitude from M 3.7 to 4.5. The scaling relationship between rupture area and moment magnitude, found for the investigated events at The Geysers, resembles that of a published empirical relationship derived for field and aftershock data for events from M 4.5 to 8.3. In order to perform spatio-temporal analysis of the subsurface water saturation, we compiled and analyzed four seismicity catalogs for the area around the injection well over the time period from October 2011 to February 2015. The catalogs consist of automatically processed events, analyst reviewed events, double-difference located events, and a subset of events with high precision locations. The catalogs contain varying numbers of events with varying precision of hypocenter locations. The result of our analysis is that the detected events need to be relocated using a 3D joint inversion for double difference hypocenter locations and P- and S-wave velocity structure. The advantage of this approach is that it combines the individual strengths of the separate catalogs.

Simulation of Injection and Production and MEQ in Large-Scale Fracture Networks Moien Farmahini-Farahani and Ahmad GhassemiMewbourne School of Petroleum & Geological Engineering, University of Oklahoma, Norman OK, U.S.A.

Keywords: Large scale fracture network, Fast multipole method, Displacement discontinuity method, Rate-and-state friction, Micro-earthquakes

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Economical production from engineered fractures of reservoirs requires reliable estimation of fluid flow, permeability, and triggered micro-seismicity in large fracture networks. In this work a fast multipole displacement discontinuity method is employed to simulate the response of large-scale natural fracture networks to injection and production. This simulation includes pressure change inside the fracture network, induced normal and shear displacement, slip, dilation, friction coefficient, seismic moment, and micro-earthquakes under anisotropic in-situ stresses acting on a randomly generated set of fractures. Rate-and-state friction model and Mohr-Coulomb criteria are used to model slip and micro-earthquakes. Case studies, representing two fracture network scales having different fracture distributions are presented. Results show that increase in pressure inside fully connected fractures leads to slip events and nucleation of high magnitude micro-earthquakes. Orientation of fractures and fluid pressure interaction are influential factors for nucleation of earthquake slip events.

Geologic Setting of the Proposed Fallon Forge Site, Nevada: Suitability for EGS Research and DevelopmentJames E. Faulds1, Douglas Blankenship2, Nicholas H. Hinz1, Andrew Sabin3, Josh Nordquist4, Stephen Hickman5, Jonathan Glen5, Mack Kennedy6, Drew L. Siler6, Ann Robertson-Tait7, Colin Williams5, Peter Drakos4, and Wendy Calvin8 1Nevada Bureau of Mines and Geology, University of Nevada, Reno, Nevada2Sandia National Laboratories, Albuquerque, New Mexico • 3U.S. Navy Geothermal Program Office4Ormat Nevada, Inc. • 5U.S. Geological Survey, Menlo Park, California6Lawrence Berkeley National Laboratory, Berkeley, California • 7GeothermEx/Schlumberger8Department of Geological Sciences and Engineering, University of Nevada, Reno

Keywords: Great Basin, Fallon, Nevada, EGS, structural setting, permeabilityThe proposed Fallon FORGE site lies within and adjacent to the Naval Air Station Fallon (NASF) directly southeast of the town

of Fallon, Nevada, within the large basin of the Carson Sink in west-central Nevada. The site is located on two parcels that include land owned by the NASF and leased and owned by Ormat Nevada, Inc. The Carson Sink in the vicinity of the Fallon site is covered by Quaternary deposits, including alluvial fan, eolian, and lacustrine sediments. Four wells penetrate the entire Neogene section and bottom in Mesozoic basement. Late Miocene to Quaternary basin-fill sediments are 0.5 to >1 km thick and overlie Oligocene-Miocene volcanic and lesser sedimentary rocks. The volcanic section is 0.5 to 1.0 km thick and dominated by Miocene mafic lavas. The Neogene section rests nonconformably on heterogeneous Mesozoic basement, which consists of Triassic-Jurassic metamorphic rocks intruded by Cretaceous granitic plutons. The structural framework is dominated by a gently west-tilted half graben cut by moderately to steeply dipping N- to NNE-striking normal faults that dip both east and west. Quaternary faults have not been observed within the proposed FORGE site.

Fallon was selected for a potential FORGE site due to its extensional tectonic setting, abundance of available data, existing infra-structure, and documented temperatures, permeability, and lithologic composition of potential reservoirs that fall within the ranges specified by DOE for FORGE. Since the early 1970s, more than 45 wells have been drilled for geothermal exploration within the area. Four exploration wells within the FORGE site are available for use in the project. Several additional wells are available for monitoring outside the central FORGE site within the NASF and Ormat lease area, including numerous temperature gradient holes. There is an existing, ten-station micro-seismic earthquake (MEQ) array that has been collecting data since 2001; the MEQ array can be expanded to encompass the entire Fallon project. The well data indicate that a sizeable area (~4.5 km2) has adequate temperatures in crystalline basement but lacks sufficient permeability within the proposed FORGE site. There are two possible, competent target formations in Mesozoic basement for stimulation in the FORGE project area: 1) Jurassic felsic metavolcanic rocks/and or metaquartzite; and 2) Cretaceous granitic intrusions. These units make up at least 3 km3 in the project area and have target temperatures of ~175-215oC. The abundant well data and detailed geophysical surveys (e.g., gravity, MT, and seismic reflection) provide significant subsurface control for the site and will permit development of a detailed 3D model. The documented temperatures, low permeability, and basement li-thologies, as well as abundant available data facilitate development of a site dedicated to testing and improving new EGS technologies and techniques, thus making Fallon an ideal candidate for FORGE.

Hydro-Shearing and Hydraulic Fracturing for Enhanced Geothermal Systems in Archetypical Normal, Strike-Slip, and Thrust Faulting TerrainsAleta Finnila1, William Dershowitz1, Thomas Doe1, and Robert McLaren2 • afinnila@golder.com1Golder Associates Inc., Redmond WA, USA • 2Golder Associates Ltd., Cambridge, Ontario, Canada

Keywords: Enhanced geothermal systems (EGS), discrete fracture network (DFN), hydraulic fracturing, critical stress, hydro-shearing, thrust faulting, strike-slip faulting, normal faulting, stimulation model

This paper advances understanding of the feasible space of Enhanced Geothermal Systems (EGS) by evaluating the effects of in situ stress, natural fracture patterns, and hydraulic stimulation on processes of geothermal conduction and convection. EGS require stimulation techniques to improve fracture network transmissivity in sparsely fractured rock masses in a way that balances conductive and convective heat transport. Three archetypical terrains with in situ stress typical of normal, strike-slip and thrust faulting regions of North America are hydraulically fractured and hydro-sheared in Discrete Fracture Network (DFN) models so that the total available fracture area and fracture spacing at depth become sufficient for geothermal energy production.

The adequacy of fracture spacing and area was determined using analytic equations for parallel fractures of uniform aperture which are considered a best case scenario. Connected fracture networks are developed using simulation of both hydro-shearing of existing natural fractures and induced tensile fracturing. The average initial temperature of the reservoir was required to be 200°C and this

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constraint along with the regional thermal gradient was used to define the depth of the geothermal reservoir. Pumping pressures and durations required to develop and later utilize these systems are discussed.

Low geothermal gradients and high minimum stress values limit the practicality of creating EGS resources in major thrust faulting regions of the United States. Development of EGS in normal and strike-slip faulting regions seems to be more tractable, but potentially requires horizontal drilling for both the stimulation well and any injection or production wells. Differences in rock lithology affect constraints on fracture spacing. Designing an appropriate stimulation program that balances enhancing the reservoir permeability while maintaining adequate fracture spacing is challenging.

Data Archiving and Lessons Learned From the Pioneering Hot Dry Rock Project at Fenton Hill, USASharad Kelkar1, Daniella Martinez1, Donald Brown2, and Leigh House2 1Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA.2Retired, Los Alamos National Laboratory, Los Alamos, NM, USA

Keywords: EGS, geothermal, stimulation, modeling, Fenton Hill, data archivingInterest in geothermal energy production has grown rapidly in recent years due to the increasing demand for clean, renewable,

domestic energy. Recent publications have suggested that geothermal energy from Enhanced Geothermal Systems could satisfy a large portion of the energy needs in the U.S. if the technology were implemented on a large scale. Reservoir-scale models are necessary in order to make informed decisions regarding optimal EGS reservoir development, and in order to be reliable such models require validation. Valuable contributions of the work presented here include the ability to provide data and insights obtained from the Fenton Hill project to the geothermal community.

Pertinent to this day are many of the lessons learned from the pioneering Hot Dry Rock project aimed at producing usable energy from the heat of the earth, conducted from 1970 to 1995 at Fenton Hill, New Mexico, USA. During this project, the Los Alamos National Laboratory created and tested two reservoirs at depths in the range of 2.8 to 3.5 km in crystalline rock formations underlying the Fenton Hill site. Thermal energies in the range of 3 – 10 MWt were produced, demonstrating the feasibility of the concept. Many important lessons were learned regarding the creation, engineering and operation of such subsurface systems – these lessons will prove valuable as the geothermal community moves towards the goal of realizing the immense potential of this ubiquitous renewable energy resource.

Fracture Characterization Using Resistivity Measured at Different Frequencies in RocksKewen Li1, Baozhi Pan1,2, and Roland Horne1 1Stanford Geothermal Program, Stanford University, Stanford, CA USA • 2Jilin University • kewenli@stanford.edu

Keywords: Fracture characterization, resistivity, different frequencies, fractured rock, EGSOne of the key issues to a successful EGS (Enhanced Geothermal System) is the creation of a great density of fractures. The detec-

tion and characterization of the created fractures is crucial in evaluating the geothermal energy resources in such EGS projects. There exist a few methods to evaluate the fractures after stimulation. However the methods have some limitations. To this end, an approach to detecting and evaluating the fractures using resistivity data measured at different frequencies has been developed in this study. The effects of fractures on resistivity measurements at different frequencies have been investigated as a function of water saturation in rocks with different porosity, permeability and lithology. Different rocks (Berea, sandstone, greywacke from The Geysers geothermal reser-voir) were used in this study. The permeability of the samples ranged from 0.5 to over 1000 md for the matrix. The frequency ranged from 100 to over 100,000 Hz. It was found that the effect of frequency on resistivity is different in rocks with and without fractures, especially in the range of low water saturation. The validity of the Archie equation depends on the existence of fractures, frequency, and the range of water saturation. The relationship between resistivity and water saturation did not follow the Archie equation at low water saturation in some rocks with fractures. Models for characterizing different types of rocks with specific fracture patterns have been established using the resistivity data measured at different frequencies and different water saturations.

Permeability Measurements of Fractured Granite at 350-450 °C Under Confining StressTatsuya Numakura, Noriaki Watanabe, Kiyotoshi Sakaguchi, Takuma Kikuchi, and Noriyoshi Tsuchiya Graduate School of Environmental Studies, Tohoku University, Japan

Keywords: Elastic-plastic transition, brittle-ductile transition, EGS, permeability, fracture, granite, ductile zoneA new concept of enhanced geothermal system, in which a reservoir is created in ductile basement rocks, has been proposed re-

cently. One of possible ways to create a fracture network in a ductile rock is thermal and/or hydraulic fracturing. Although creating fractures may be possible, there is concern about the permeability of the fractured rock after recovery of temperature and/or effective confining stress to the initial state, at which plastic deformation of fracture may occur. The present study has experimentally explored permeability of thermally fractured granite at various combinations of temperature (up to 450 °C) and effective confining stress (up to 90 MPa). It has been found that transition from elastic to plastic deformation occurs at a specific stress level (i.e., the elastic-plastic transition stress), depending on temperature. The elastic-plastic transition stress decreases with increasing temperature, for which an empirical equation has been presented. At both elastic and plastic conditions, relations between log permeability and log effective confining stress are linear, and the slope of the linear curves are independent of temperature. Reduction of log permeability by incre-ment of log effective confining stress is larger for the plastic condition. Based on these findings, a way to roughly predict permeability of fractured granite at various combinations of temperature and effective confining stress has been developed. It indicates that the method can provide reasonable prediction results at both elastic and plastic conditions.

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Completion Design Considerations for a Horizontal Enhanced Geothermal SystemJeffrey Olson1, Dr. Alfred Eustes1, Dr. William Fleckenstein1, Erdinc Eker1, Reed Baker1, and Chad Augustine2 1Colorado School of Mines • 2National Renewable Energy Laboratory

Keywords: Completions, EGS, casing, cementing, zonal isolation, horizontalThe petroleum industry has had considerable success in recent decades in developing unconventional shale plays using horizontal

drilling and multi-zonal isolation and stimulation techniques to fracture tight formations to enable the commercial production of oil and gas. Similar well completions could be used in Enhanced Geothermal Systems (EGS) to create multiple fractures from horizontal wells. This study assesses whether well completion techniques used in the unconventional shale industry to create multi-stage fractures can be applied to an enhanced geothermal system, with a focus on the completion of the EGS injection well.

This study assumes an Enhanced Geothermal System (EGS) consisting of a central horizontal injection well flanked on each side by horizontal production wells, connected to the injection well by multiple fractures. The focus is on the design and completion of the horizontal well. For the purpose of developing design criteria, a reservoir temperature of 200°C (392°F) and an injection well flow rate of 87,000 barrels per day (160 kg/s), corresponding to production well flow rates of 43,500 barrels per day (80 kg/s) is assumed. The analysis found that 9-5/8″ 53.5 pounds per foot (ppf) P110 casing string with premium connections meets all design criteria for the horizontal section of injection well. A P110 grade is fairly common and is often used in horizontal sections of shale development wells in petroleum operations.

Next, several zonal isolation systems commonly used in the shale gas industry were evaluated. Three techniques were evaluated – a “plug and perf” design, a “sand and perf” design, and a “packer and port” design. A plug and perf system utilizes a cemented casing throughout the length of the injector wellbore. The sand and perf system is identical to the plug and perf system, but replaces packers with sand placed in the casing after stimulation to screen out the stimulated perforated zones and provide zonal isolation. The packer and port completion approach utilizes an open horizontal hole that zonally isolates areas through the use of external packers and a liner.

A review of technologies used in these systems was performed to determine if commercially available equipment from the petroleum industry could be used at the temperatures, pressures, and sizes encountered in geothermal settings. The study found no major technical barriers to employing shale gas multi-zonal completion techniques in a horizontal well in a geothermal setting for EGS development. For all techniques considered, temperature limitations of equipment are a concern. Commercially available equipment designed to operate at the high temperatures encountered in geothermal systems are available, but is generally unproven for geothermal applica-tions. Based on the study, further evaluation of adapting oil and gas completion techniques to EGS is warranted.

Geologic Setting of the Proposed West Flank Forge Site, California: Suitability for EGS Research and DevelopmentAndrew Sabin1, Kelly Blake1, Mike Lazaro1, Douglas Blankenship2, Mack Kennedy3, Jess McCullough4, Steve DeOreo4, Ste-phen Hickman5, Jonathan Glen5, Ole Kaven5, Colin Williams5, Geoff Phelps5, James E. Faulds6, Nick Hinz6, Wendy Calvin7, Drew Siler3, and Ann Robertson-Tait8 1U.S. Navy Geothermal Program Office, China Lake CA • 2Sandia National Laboratories, Albuquerque, NMst3Lawrence Berkeley National Laboratory, Berkeley CA • 4Coso Operating Company LLC, Coso Junction CA 5U.S. Geological Survey, Menlo Park CA • 6Nevada Bureau of Mines and Geology, University of Nevada, Reno NV7Department of Geological Sciences and Engineering, University of Nevada, Reno NV • 8GeothermEx/Schlumberger

Keywords: Coso geothermal field, China Lake, California, EGS, structural setting, permeability The proposed West Flank FORGE site is within the China Lake Naval Air Weapons Station (NAWS), China Lake, CA. The West

Flank is west of the Coso geothermal field, an area of China Lake NAWS dominated by the Quaternary Coso volcanic field largely comprised of rhyolite domes and their volcaniclastic and epiclastic horizons. The largest dome flow complex, Sugarloaf Mountain, marks the northwestern margin of the geothermal field. The West Flank is situated due west of Sugarloaf. The geologic setting of the West Flank was determined from one deep well (83-11) drilled as a potential production hole in 2009. The bottom-hole temperature (BHT) of well 83-11 approaches 600 oF (315˚C), but flow tests demonstrate very low, non-commercial permeabilities. With the ex-ception of the upper 600 feet of volcaniclastic alluvium, well 83-11 is completed in granitic basement. The West Flank possesses the primary attributes of a FORGE site: non-commercial permeability (<10-16m2), a 175˚ to 225˚C temperature range in crystalline rocks, and a location outside an existing geothermal field.

The Coso Mountains host the Coso volcanic field and are within a right-releasing stepover between the dextral Airport Lake (ALF) and Little Lake fault zones (LLFZ) and the Wild Horse Mesa and Owens Valley faults. Two distinct fault populations have been identi-fied at Coso: WNW-trending and antithetical, NE-trending strike-slip faults and N- to NNE-trending normal faults. These faults are both high permeability drilling targets at depth within the main (productive) geothermal field and they locally segment the field into distinct hydrothermal regimes. The West Flank may be segmented from the rest of the field by one such northerly trending fault. The overall minimum principal stress orientation in the main geothermal field varies from 103˚ to 108˚; however, the minimum horizontal principal stress in 83-11 is rotated to 081˚.

Numerical Simulation Model Comparisons for Enhanced Geothermal ReservoirsIvan G. Vazquez-Rubio, Davood Bahrami, and George Danko • University of Nevada, Reno

Keywords: Enhanced geothermal system, numerical simulation models, models comparison, engineering, reservoir designFractures and fault layers are important conduits for coolant transportation in a geothermal reservoir. The heat exchange between

the fluid and hot rock is affected by the fracture and transmisivity of the rock. The focus of the study is to model the fracture responses

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to Thermal-Hydrology-Mechanical (T-H-M) factors. Two studies have been conducted as part of the US department of Energy (DOE), Geothermal Technology Office (GTO)’s Code Comparison Study (GTO-CCS) with different model simulation approaches. The first study involves a poroelastic fault layer in a geothermal reservoir undergoing water injection. The non-linear responses are studied between the injection rates and pressures during the 3 day time period simulation. The second study considers the responses of a single planar fracture in hot rock, based on the first experimental Enhanced Geothermal System (EGS) in the U.S. at Fenton Hill, Phase 1. This study simulates the reservoir for a 24 day period of injection and heat production where T-H-M responses are experienced. The purpose of the second study is to match the measured production temperature at the extraction point and pressure loss across the fracture due to a constant injection rate at Fenton Hill. Fourteen reservoir simulation codes were used by 11 participants at national U.S. institutions to conduct the studies. The poster describes the results which include those obtained at UNR. Comparisons are shown between different modeling approaches applicable to the fracture flow simulations in engineered geothermal systems.

Thermal and Trace-Element Anomalies in the Eastern Snake River Plain Aquifer: Toward a Conceptual Model of the EGS Resource J. A. Welhan • Idaho Geological Survey, Idaho State University, Pocatello, Idaho

Keywords: EGS, ESRP, rhyolite, thermal water, chemical tracers, conceptual modelData on temperature and chemistry of thermally-influenced ground water in the eastern Snake River Plain aquifer were examined

to determine how such information could be used to inform on heat transport from the hot rhyolitic rocks that underlie the aquifer. The U.S. Geological Survey’s NWIS database reveals the existence of several thermally-influenced areas located near the margins of the aquifer, where ground water temperatures are associated with distinctive water chemistry. The associated enrichments in F, Li and B in these waters are diagnostic of water-rock chemical reactions with felsic rocks under thermal conditions. The chemistry of thermal waters sampled in a deep borehole drilled into rhyodacite and welded tuff beneath the Idaho National Laboratory (INL) to a depth of 3.2 km bears the geochemical fingerprint of such interaction with hot felsic rock.

Based on an analysis of temperature data in a thermal anomaly located in the central ESRP aquifer south of the INL, an estimate of the thermal water flux through the base of the aquifer, derived via a two-component mixing model, is incompatible with core-scale data on hydraulic conductivity (K) of the rhyolite. This suggests that advective heat transport from the rhyolite is not spatially uniform but focused in localized, high-K preferential flow paths within the rhyolite and mineralized basalts that overlie the rhyolite. This inter-pretation is consistent with data on the fracture-flow characteristics of rhyolitic basement and sheds new light on the spatial distribution of thermally influenced ground water near the margins of the ESRP aquifer in the area of the INL.

exploration

Pavant Butte, Utah Geothermal Prospect RevisitedRick Allis1, Christian Hardwick1, Mark Gwynn1, and Stu Johnson2 1Utah Geological Survey, Salt Lake City UT • 2San Diego CArickallis@utah.gov • christianhardwick@utah.gov • markgwynn@utah.gov • stuartdjohnson1@gmail.com

Keywords: Pavant Butte, Black Rock Desert, heat flow, gravity, resistivity, magnetotelluric soundings, seismic reflection surveys, stratigraphic reservoirs

An equilibrium temperature log run down to 2.2 km depth in the Pavant Butte oil exploration well three years after it was plugged and abandoned indicates temperatures of 240°C at 3 km depth and 280°C at 4 km. Heat-flow measurements from the Black Rock Desert around this well suggest the main thermal anomaly is at least 50 km2 in area. High permeability in a potential reservoir at about 3 km depth may be provided by a combination of Quaternary faults that have shaped the basin lying beneath this area and stratigraphic permeability within the Cambrian metasedimentary package that lies immediately beneath the Tertiary to Quaternary basin fill. The shape of the bedrock surface is determined from interpretation of a 30 mGal gravity anomaly extending north-south in the central Black Rock Desert. Geophysical log measurements of density and porosity in oil exploration wells reveal a gradational density gradient with depth in the basin and a diminished gradient near the basin flanks. This is due to the change from paleo-lake sediments with high clay content in the central basin, to more sandy, coarser sediments on the basin flanks. The resistivity of the central basin-fill sediments is very low (0.5 – 3.0 ohm-m), which limits the ability of magnetotelluric soundings to delineate the bedrock surface here. Seismic reflection surveying is considered the best technique for mapping the reservoir beneath the basin. Additional heat flow measurements are also recommended to determine whether the geothermal resource is located centrally beneath the basin, or beneath the Pavant Butte volcano on the east side of the basin.

Will Stratigraphic Reservoirs Provide the Next Big Increase in U.S. Geothermal Power Generation?Rick Allis1, Mark Gwynn1, Christian Hardwick1, Greg Mines2, and Joseph Moore3 1Utah Geological Survey, Salt Lake City, Utah • 2Idaho National Laboratories, Idaho Falls, Idaho3Energy and Geoscience Institute, University of Utah, Salt Lake City, Utahrickallis@utah.gov • markgwynn@utah.gov • christianhardwick@utah.gov gregory.mines@inl.gov • jmoore@egi.utah.edu

Keywords: Stratigraphic reservoirs, power generation, Great Basin, Pavant Butte, Elko basins, Idaho Thrust Belt, North Steptoe Valley, permeability, levelized cost of electricity

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Economic and reservoir engineering models show that stratigraphic reservoirs have the potential to contribute significant geothermal power in the U.S. If the reservoir temperature exceeds about 150 – 200 °C at 2 – 4 km depth, respectively, and there is good perme-ability, then these resources can generate power with a levelized cost of electricity (LCOE) of close to 10 ¢/kWh (without subsidies) on a 100 MW power plant scale. There is considerable evidence from both groundwater geology and petroleum reservoir geology that relatively clean carbonates and sandstones have, and can sustain, the required high permeability to depths of at least 5 km. This paper identifies four attractive stratigraphic reservoir prospects which are all located in the eastern Great Basin, and have temperatures of 160 – 230 °C at 3 – 3.5 km depth. They are the Elko basins (Nevada), North Steptoe Valley (Nevada), Pavant Butte (Utah), and the Idaho Thrust Belt. The reservoir lithologies are Paleozoic carbonates in the first three, and Jurassic sandstone and carbonate in the Idaho Thrust Belt. All reservoir lithologies are known to have high permeability characteristics. At North Steptoe Valley and Pavant Butte, nearby transmission line options allow interconnection to the California power market. Modern techniques for drilling and developing tight oil and gas reservoirs are expected to have application to geothermal development of these reservoirs.

Heat Flow and Helium Isotopes in the Geothermal Areas of Tuscany (Central Italy)Stefano Bellani, Gabriella Magro, and Fabrizio Gherardi CNR - Istituto di Geoscienze e Georisorse, Pisa, Italy • sbellani@igg.cnr.it • g.magro@igg.cnr.it • f.gherardi@igg.cnr.it

Keywords: Heat flow, helium isotopes, deep seismic profiles, geothermal fields, TuscanyA wide part of Tuscany is affected by a large heat-flow anomaly, with maxima corresponding to the geothermal fields of Larderello-

Travale and Mt. Amiata. Anomalous heat flow is very often related to the presence of 3He-enriched fluids. The comparison of R/Ra, He/Ne ratios and heat flow through Tuscany along three deep seismic profiles, shows no straightforward correlation among these parameters. A phased correlation exists at Larderello-Travale, where maxima are almost coincident, while they appear decoupled at Mt. Amiata.

Different heat and He transport mechanisms through the crust are the most likely explanation. At Larderello-Travale, the almost constant value of R/Ra in fluids issuing at surface indicates that the contribution of hot 3He-enriched fluids must have occurred through deeply rooted faults.

The decoupling of the heat and He anomalies in the Mt. Amiata area is then related not only to a lower degree of fracturing and/or a different depth of the faults roots, but also to infiltration of meteoric water in shallow aquifers.

Naval Air Station Fallon Mainside: Update of Geothermal ExplorationKelly Blake, Andrew Tiedeman, Andrew Sabin, Michael Lazaro, Dave Meade, and Wei-Chuang Huang Navy Geothermal Program Office

Keywords: Exploration, geology, geophysics, well testing, basin and rangeThe Navy Geothermal Program Office renewed exploration on the southeastern portion of the Naval Air Station Fallon mainside

installation in the last three years. Based on numerous geophysical datasets, refined locations, potential offsets and the attitudes of through going faults were determined. Six recently drilled or deepened exploration holes have yielded a more detailed understanding of the potential geothermal reservoir, from deep (>9,000 feet) altered metasediments and intrusive rocks to shallower, Tertiary volcanics. These are capped by the low permeability Lahontan Valley Group lakebed sediments. Image logs were collected from wells to gain a better understanding of bedding, fractures and stress. The calculated principal stress orientation from east to west rotates 020˚ to the north and when considered with other geophysical data, suggests a change in structural orientation to the east of the mainside instal-lation. Fluid temperatures and flow were tested in select wells using air lifts, nitrogen lifts and pump tests. These have demonstrated that a high permeability target is at the lithologic contact between the lakebed sediments of the Lahontan Valley Group and the Tertiary volcanic flows. Continued efforts proposed by GPO to understand this resource includes pump testing the 88-24 and 86-25 exploration holes and refining an initial 3D model of the region.

Stochastic Modeling and Analysis of Temperature Data From Hot Springs in Yellowstone Caldera, Wyoming, USA Cary Lindsey1, Jerry Fairley1, Peter Larson2, and Nicholas McMillan2 1Department of Geosciences, University of Idaho • 2School of the Environment, Washington State University

Keywords: Hydrology, time-series temperatures, ARMA modeling, Yellowstone caldera, geothermal springs, deuterium isotope doping

We monitored temperatures in three geothermal springs located in Lower Geyser Basin of the Yellowstone caldera, Yellowstone National Park, Wyoming, USA. The observed temperatures were analyzed using autoregressive moving average (ARMA) models to represent the underlying generating processes responsible for the observed temperature distributions. An attempt was made to attribute physical significance to the ARMA model parameters by comparing the time lags of the model coefficients with characteristic times observed for the same springs in a related study, but this effort was unsuccessful. In spite of the empirical nature of ARMA models, and their apparent lack of relationship with readily observed physical drivers, the fact that they provide minimum variance, optimal forecasts of time-correlated univariate variables, their ability to detect changes in time-series structure, and their usefulness in boot-strapping parameter estimates give them a high degree of utility, which has been underutilized in the geosciences.

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Ice Box Calorimetry: A Test of Applicability in Non-Steaming Geothermal AreasCary Lindsey1, Brady Lubenow1, Jerry Fairley1, and Peter Larson2 1Department of Geosciences, University of Idaho • 2School of the Environment, Washington State University

Keywords: Heat flux, calorimetry, Yellowstone, geothermal, calorimeter, ice boxSurface heat flux, an important tool for characterizing geothermal areas, is often difficult, if not impossible, to measure directly. In

this study we present an analysis of icebox calorimetry (IBC), a method that has, to date, been used only in geothermal areas with steam-ing ground. We test the method in varied geothermal environments and present possible refinements, pitfalls, and suitable applications.

Investigating Potential Geothermal Resources in Western Saudi ArabiaRobert J. Mellors1, Victor Camp2, David Harris3, and Abdullah Al-Amri4 1Lawrence Livermore National Laboratory • 2San Diego State University • 3Deschutes Signal Processing4King Saud University, Saudi Arabia

Keywords: Saudi Arabia, seismology, geology, volcanic, geothermalSaudi Arabia offers a strong potential for geothermal energy, but only a limited amount of exploration efforts have taken place.

We are beginning a preliminary, low-cost, reconnaissance level evaluation of the volcanic area based on mapped geology and existing passive seismic data. Particular focus is on identifying areas with possible shallow magma chambers by looking for micro-seismicity, anomalous attenuation, and low velocities. The emphasis is on the Harrat Rahat volcanic area in western Saudi Arabia, but if the procedure appears feasible, we hope to expand to other areas. The goal is to test the procedure and identify areas for future, more intensive study.

Plumbing and Political Will: Low Temperature Geothermal Power Exploration in Pagosa Springs, ColoradoDr. Leland Mink1, Jerry Smith2, Kirsten Skeehan2, and Paul Foley2 1Mink Geohydro • 2Pagosa Verde, LLC

Keywords: Rural development, public/private collaboration, exploration, district heating, low-temperature, thermal gradient, geochemistry

Pagosa Springs, Colorado has had a geothermal resource utilized by direct use heating and commercial hot springs resorts for de-cades. Recent exploration activities in the region have been funded and supported by federal and local government agencies to explore the potential for geothermal power in the region. The local political situation has previously hindered geothermal power exploration but recent support has proven necessary to the activities undertaken. Geophysical studies and surface geochemistry identified six potential thermal gradient drilling locations to the south of the Pagosa Springs downtown of which three wells were drilled. Temperature logs and geochemistry from these wells indicates a power producing geothermal resource is most likely found to the west of downtown.

Earthquake-Related Stress Concentrations and Permeability Generation in Geothermal SystemsDrew L. Siler1, James E. Faulds2, and Nicholas H. Hinz2 1Earth Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA2Nevada Bureau of Mines and Geology, University of Nevada, Reno, USA

Keywords: Permeability, structure, fault, Salt Wells, Brady’s, stress, fluid flowThe local tectonic stress field is perturbed during seismic events. The location and extent of the affected area and the magnitude

of the perturbation are controlled by the magnitude of the earthquake and the length of the slipped fault. In certain locations these deformation-related stresses are additive to the regional tectonic stress conditions. These areas of stress concentration have been shown to be associated with elevated permeability and localization of fluid flow. We show that this concept holds true in geothermal systems through modelling of earthquake-related stress changes at two Great Basin geothermal systems, Salt Wells and Brady’s. In both sys-tems the areas of maximum stress concentration that result from modelled seismicity are spatially correlated with the geothermal well fields and surficial geothermal features, as well as with the highest downhole temperatures in the respective well fields. Furthermore, the magnitude of the stress increases are sufficiently high to bring some faults into a critically stressed state; a state where faults and fractures readily serve as fluid flow conduits. These results indicate that the stress changes occurring during seismicity assert some control permeability generation and maintenance in geothermal systems. We suggest that periodic slip on the primary controlling faults in geothermal fields leads to repeated stress concentration and faulting and fracturing in the same areas over time. The resultant perme-ability, continually maintained by repeated stressing and slip, is enhanced relative to surrounding areas where faults are less active and/or the intervals between seismic events are longer. The areas of stress concentration that occur as a result of earthquake slip may be as small as 100s of meters wide. Thus, these methods allow for assessment of permeability and fluid flow potential in geothermal fields at this fine scale. As geothermal resource exploration and development continues to focus on new, commonly blind and/or data sparse geothermal fields, such tools with the ability to assess the variation in important geothermal parameters like permeability at these fine scales, will become increasingly important for mitigation of exploration cost and risk.

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GeoChemistry

Fluoride in Geothermal Waters, IndiaV. Chandrasekhar1, D. Chandrasekharam1,2, G. Trupti1,2, and H. K. Singh2 1GeoSyndicate Power Pvt. Ltd, Mumbai, India • 2Department of Earth Sciences, Indian Institute of Technology Bombay

Keywords: Fluoride, geothermal waters, India, radiogenic granite, EGSFluoride content in geothermal waters circulating in granites is much higher compared to those flowing through basaltic rocks.

Water-granite interaction for prolonged period of time (~50 years) at elevated temperatures (~200 °C) results in high content of fluoride in thermal waters. Mica and amphiboles and fluorapatite are the main source for fluoride in geothermal waters. The fluoride content can be used as a path finder to target granites for EGS projects.

Applications of Downhole Lithogeochemistry to Geothermal ExplorationR. B. Libbey and A. E. Williams-Jones • McGill University

Keywords: Lithogeochemistry, resource vectoring, mass transfer, volume estimates, Reykjanes, IcelandLithogeochemical investigations of geothermal systems can assist with the characterization of upflow geometries, hydrothermal

mineralogy, permeable horizons, system volumes, and downhole stratigraphy and stratigraphic offsets. Despite the relevance of this information to geothermal field exploration and development, lithogeochemistry remains an under-utilized tool by the geothermal industry. This study illustrates the application of downhole lithogeochemistry to geothermal exploration with a case study from the Reykjanes geothermal system, Iceland. Trends in the distribution of reactive-mobile elements correspond closely to the large-scale hydrology of the system. Applications of lithogeochemical data to system volume estimations are discussed.

Variations in the Composition of Epidote in the Karaha-Telaga Bodas Geothermal SystemEmma Grace McConville1, Dr. Philip Candela2, Philip Piccoli2, and Joseph Moore3 1University of Maryland • 2Advisor, University of Maryland • 3Advisor, University of Utah

Keywords: Indonesia, Galunggung volcano, Karaha-Telaga Bodas, geothermal, epidote, chlorite and plagioclaseThe Karaha-Telaga Bodas vapor-dominated geothermal system is located on the flank of the active Galunggung volcano in West

Java. This study will focus on the epidote-bearing mineral assemblages in the system and the chemical reactions that produce epidote. Compositional variability in hydrothermal epidote has been attributed to a number of possible factors including bulk rock composition, fluid chemistry, water to rock ratios, and variations in temperature and pressure. This study aims to evaluate whether the chemical composition of epidote is influenced by: (1) the composition of associated plagioclase, (2) distance from veins, and (3) depth. This study will use wavelength dispersive spectroscopy analysis and X-ray diffraction analysis to facilitate the identification of influential variables in determining the variation in the composition of epidote in the Karaha-Telaga Bodas geothermal system. Initial findings suggest that the plagioclase composition and the distance from veins and depth do not play a role in epidote composition. Neverthe-less, chlorite composition does appear to change with depth. Adjustments to the initial hypotheses and new hypotheses have evolved as a result of the initial data.

The Importance of Hydrodynamic Conditions in Silicate Scale Growth Inferred From Numerical SimulationAkihiro Mizushima, Hitoshi Mikada, and Junichi TakekawaDept. of Civil and Earth Res. Eng., Kyoto University

Keywords: Silica, scaling, numerical simulation, lattice Boltzmann method, hydrodynamics, chemical kineticsSilica scaling remains to be a major restriction for geothermal heat extraction. Our goal is to compare the effect of the direct che-

misorption of monometric silica and the adhesion of colloidal silica on the silica scaling. To meet this goal, we compare the simulation result of the amount and the distribution of silica deposition predicted by the chemical kinetic and the hydrodynamic deposition process and the data from a laboratory or a field experiment. We solve the fluid, the temperature and the dissolved silica concentration field using the lattice Boltzmann method. From our simulation result, it is found that the kinetic process is not only quantitative evaluation of the amount of silica deposition but also the prediction of the distribution of it. It is, therefore, necessary to emphasize the adhesion of the colloidal silica should be take into account for reproducing silica scaling.

Geothermometric Temperature Comparison of Hot Springs and Wells in Southern IdahoGhanashyam Neupane1,2, Earl D. Mattson1, Travis L. McLing1,2, Patrick F. Dobson3, Mark E. Conrad3, Thomas R. Wood2,4, Cody Cannon2,4, and Wade Worthing2,4 • ghanashyam.neupane@inl.gov1Idaho National Laboratory, Idaho Falls ID, USA • 2Center for Advanced Energy Studies, Idaho Falls ID, USA3Lawrence Berkeley National Laboratory, Berkeley CA, USA • 4University of Idaho-Idaho Falls, Idaho Falls ID, USA

Keywords: Geothermal sites, hot springs, wells, reservoir temperature, Snake River Plain, RTEstConventional geothermal resource prospecting often begins with geochemical analysis of geothermal fluids sampled from surface

expressions (hot springs and fumaroles). Similarly, water samples from hot wells located near the surface expressions are also routinely collected and analyzed as a part of regional exploration efforts. The chemical compositions of these water samples can be used to

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assess the likely reservoir temperatures of the geothermal sites as well as to understand other reservoir characteristics. In this paper, we present comparative results of geothermometric reservoir temperatures based on water compositions measured from pairs of hot springs and nearby wells of 10 potential geothermal sites in southern Idaho using both traditional and multicomponent equilibrium geothermometric approaches. Our results show that the reservoir temperatures estimated using water compositions measured surface thermal features and wells produce similar results. However, for two of the 10 sites, Durfee Hot Spring and Fairchild Hot Spring, the estimated reservoir temperatures based on water compositions measured from hot springs were significantly higher than the estimated reservoir temperatures using the well water sample. In the case of the Durfee system, the well water may have chemically re-equilibrated within the aquifer resulting in a lower estimated temperature than that calculated using the hot spring. Similarly, in the case of the Fairchild system, the hot spring and well water chemistry are chemically distinct and had the greatest distance between the hot spring and well pairs of the examined geothermal sites. The difference in fluid chemistry suggests that the Fairchild Hot Spring reservoir is compartmentalized and the two expressions are issuing waters migrated from two separate portions of the reservoir. Although the majority of the hot spring/well pairs in southern Idaho provided concordant reservoir temperatures, it is imperative to consider the consistency of the water types and distance between the sources when estimating reservoir temperatures.

Assessment of the Downhole Geochemical Report of OW-917Ruth Wamalwa • Olkaria • rwamalwa@kengen.co.ke

Keywords: Down hole chemistry, drilled well chemistry, evaluation of geochemical characteristicsThe exploitation of geothermal energy resources necessitate detailed understanding of drilled wells’ chemistry. This information

together with that collected from other disciplines helps in well evaluation, evaluation of geochemical characteristics of accessible geothermal sources, well siting, environmental impact assessment. This is made possible by discharging the wells accompanied with programmed sampling and analysis of the chemical components of the discharged fluids until when the chemistry is deemed stable; approximately after two months of well discharge. Problems of low pressures in some wells have led to some wells failing to discharge upon several attempts of stimulation hence leading to gaps in information; a scenario in OW-917. This paper, therefore, represents a report on the down hole chemistry of the OW-917. Here the chemical characteristic of the well with depth and temperatures as given by the solute geothermometers will be assessed.

Geochemistry and Alteration Mineralogy of Well NWS-10, Mt. Sabalan Geothermal Field, NW-IranElahe Zarei1, Faramarz Tutti1, Soheil Porkhial2, and Nayyereh Mirnabavi Astanah2 1Department of Geology, College of Science, University of Tehran, Tehran, Iran2Renewable Energy Organization of Iran (SUNA)

The town of Meshkin Shahr is located in NW-Iran and has a population of 164,000. Mount Sabalan is stratovolcano, located south-east of Meshkin Shahr. The Sabalan geothermal prospect lies in the Moeil valley on the western slopes of Mt. Sabalan, approximately 16 km southeast of Meshkin Shahr, well NWS10D is the 10th geothermal well drilled at the Northwest Sabalan Geothermal Project. It is collared at Pad D and deviated towards the eastern quadrant to a target azimuth of 94°. This study considers geothermal conceptual modeling as an important tool in exploration and exploitation of geothermal resources. The main objective is to use thermal fluids and hydrothermal alteration mineral geothermometry to develop a conceptual model of the Sabalan Geothermal Field. Hydrothermal alteration mineralogy and thermal fluid chemistry are important sources of useful information in geothermal conceptual modeling. Al-teration minerals can be used to infer subsurface formation temperatures and also reconstruct the thermal history of a geothermal field. Chemical and solute geothermometers from thermal fluid analysis on the other hand help in the calculation of subsurface temperatures. The approach pursued in the study included; (1) The chemical analysis of major elements in the thermal fluids from geothermal field, in order to calculate subsurface temperatures using geothermometric equations by Fournier (1979), Arnosson et al. (1983) and Giggenbach (1988). (2) The use of lithological log from well NWS10D drilled in the afore mentioned subfields to reconstruct lithostratigraphy and hydrothermal alteration zonation. Results from calculated temperature on fluid chemistry and inferred temperatures from alteration minerals, indicate an high subsurface temperature in Sabalan Geothermal Field.

GeoloGy

The Thermal History of Garland Mineral Springs, North Cascades, Washington, From Apatite Fission Track Analysis of Well Cuttings From Geothermal Exploration Well GAR-1Owen A. Callahan1, Trenton T. Cladouhos2, Benjamin Larson3, and Richard A. Ketcham4 1The University of Texas at Austin, Bureau of Economic Geology, Austin TX • 2AltaRock Energy, Seattle WA3NOAA/PMEL, Seattle WA • 4The University of Texas at Austin, Jackson School of Geosciences, Austin TX

Keywords: Thermochronology, apatite fission track, Garland Mineral Springs, GAR-1, Snohomish Public Utility District (SnoPUD), Washington

Commercial geothermal resources in the Washington Cascades remain elusive, despite several decades of reconnaissance. Recent efforts at development include geochemical analysis and exploration drilling at Garland Mineral Springs. These springs consist of a large surface manifestation of warm water and high CO2 and magmatic He discharge. Snohomish Public Utility District funded two wells at this site: a shallow (213 m) temperature gradient hole, and exploration slimhole GAR-1 (1524 m). A promising temperature gradient observed in the shallow well, in excess of 80 °C/km, reverted to a lower gradient (~32 °C/km) below 600 m in GAR-1 Both

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wells encountered CO2-charged artesian flow and bleached granite. However, sub-economic temperatures and low flow rates forced the District to abandon the project. Material from GAR-1 is uniquely suited to address questions about the onset of hydrothermal fluid flow in low-temperature, high gas flux thermal springs found throughout the Washington Cascades, and to help characterize the geothermal resource in this region.

In this study, 4 depths were selected for apatite fission track (AFT) analysis: 201 m, 494 m, 920 m, and 1513 m. Calculated AFT ages for these depths are 16.9 (-2.7/+3.2) Ma, 14.1 (-2.6/+3.2) Ma, 10.6 (-5.7/+12.3) Ma, and 14.8 (-2.3/+2.7) Ma, respectively. The AFT ages are consistent with mid- to late-Miocene cooling documented throughout the North Cascades. Relatively long mean track lengths suggest that modern elevated temperatures cannot be long lived, nor is it likely that any sample has experienced recent tem-peratures much in excess of the modern measured temperatures. Inverse modeling of AFT data using the software program HeFTy produces thermal histories that include gradual heating beginning as early as 7 Ma, with distinct increases in warming starting after 2 Ma and accelerating after 1 Ma in some samples. Recent warming is contemporaneous with increases in volcanic activity in the region, strengthening ties between hydrothermal discharge at Garland Mineral Springs and magmatic intrusion at depth.

Tourmaline in Geothermal Systems: An Example From Darajat, IndonesiaThomas M. Etzel1,2, Joseph N. Moore2, John R. Bowman1, Clay G. Jones2, Rindu Grahabhakti Intani3, Glenn Golla3, and Greg Nash2 1Dept. of Geology and Geophysics, University of Utah, Salt Lake City UT 2Energy & Geoscience Institute, University of Utah, Salt Lake City UT • 3Chevron Geothermal Indonesia, Ltd

Keywords: Tourmaline, water-rock interaction, vapor-dominated, Indonesia, Darajat, geochemistryThe chemical compositions of two separate tourmaline populations (Stage 1 and Stage 3) from well DRJ-S1 at Darajat have been

determined. This data, alongside petrologic observations, is used to improve our understanding of the evolution of the Darajat vapor-dominated geothermal system. Stage 1 tourmalines (replacing feldspar) have distinctly higher Fe/(Fe + Mg) and Na/(Na + Ca) ratios than Stage 3 tourmalines (formed in anhydrite veins). Mineral paragenesis and the high Fe content of the tourmalines suggest that Stage 1 formed in a higher temperature, fluid-dominated environment following the emplacement of subvolcanic intrusives. Ca-abundant Stage 3 tourmalines formed after descending steam condensates causing advanced argillic alteration began to neutralize. Continued anhydrite and calcite deposition (due to the heating of descending steam condensates) at shallow levels reduced porosity and perme-ability, impeding reservoir recharge, resulting in the current vapor-dominated system.

Geothermal Implications of Rift Zone Mini-Grabens — Geological and Geophysical Structure of the Reykjafell Mini-Graben, Hengill Geothermal Field, SW IcelandBjörn S. Harðarson, Sigurdur G. Kristinsson, Ragna Karlsdóttir, and Gunnlaugur M. EinarssonIceland GeoSurvey (ISOR), Reykjavik, Iceland • bjorn.s.hardarson@isor.is

Keywords: Iceland, Hengill, Hellisheidi, rift zone, mini graben, central volcano, high-temperature geothermal field, fault, fissure, tectonics, geophysical, 1-D inversion, TEM

The active volcanic zones in Iceland are characterized by high heat-flow and extensive geothermal activity. Iceland is unique in its location being not only astride the diverging Mid-Atlantic Ridge, but also above a mantle plume. These two dynamic systems combine fundamental factors that promote magmatism, tectonics and geothermal activity. The high-temperature geothermal areas are mainly confined to volcanic systems, in particular central volcanoes, and are subject to powerful tectonic control. The Hengill central volcano hosts one of the most powerful geothermal fields in Iceland, dominated by NE-SW striking faults. It is located at the western flank of the West Iceland Volcanic Zone (WVZ), which represents the Mid-Atlantic Ridge on land forming a graben-like structure approximately 15-50 km wide and 170 km long. The Hengill low resistivity region covers about 112 km2, and presently Reykjavik Energy operates two power plants in the area with installed capacity of about 420 MWe and 430 MWt. We present preliminary results on structural mapping of a mini-graben, the Reykjafell graben, which is located at the western flank of the Hengill geothermal system and thereby flanking the WVZ. The mapped graben strikes NE-SW, it is about 7 km long, up to 400 m wide and has a down-throw of up to 200 m. Production wells which penetrate the Reykjafell mini-graben are amongst the most powerful in the area. 1D inversion of TEM resistivity data strongly suggests an up-flow zone along the Reykjafell mini-graben. These results may have significant implications for other high-temperature geothermal areas which are located in a similar tectonic setting, for example, the East African Rift System. The paper illustrates the importance of detailed structural mapping during the initial phases of geothermal exploration, as such map-ping is the most cost effective of all the following research techniques.

Examining Subsurface Processes Captured in Geothermal Host Rocks Using Computerised Tomography and Scanning Electron MicroscopyBridget Y. Lynne Department of Engineering Science, University of Auckland, Auckland, New Zealand • b.lynne@auckland.ac.nz

Keywords: CT scans, scanning electron microscopy, permeability, hydrothermal alteration, Tauhara, New ZealandThe dual techniques of Computerized Tomography (CT) and Scanning Electron Microscopy (SEM) reveal that significant sub-

surface processes are preserved in core from the Tauhara geothermal field, New Zealand. CT scans image the spatial distribution of density changes at 0.02 mm increments enabling 3D mapping of density variations within rocks. SEM images support the CT findings by documenting their associated subsurface processes. Dissolution, boiling of fluids, and thermal fluid flow resulting in silicification

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of the host rock, are three important subsurface processes documented in this study. In some cases, multiple events are recorded. The dimensions, structure and connectivity of voids and micro-fractures is also revealed. The cores examined show that some voids are connected with depth into the sample, while other areas reveal shallow disconnected voids. SEM observations on the same sample show the presence of both shallow and deep voids, confirming the CT scan findings. Micro-fracture orientations change with depth within individual samples. Some micro-fractures are infilled with crystals or clays reducing the potential permeability of these channels. The dual technique approach provides useful and significant information on the spatial distribution and timing of various subsurface processes.

Structural Constraints of Buffalo Valley Hot Springs, North-Central NevadaDanielle D. Molisee and John W. Bell • Nevada Bureau of Mines and Geology, University of Nevada, Reno, NV

Keywords: High-temperature geothermal sites, active faults, geothermal structural settings, Fish Creek mountains fault zoneThe Humboldt Structural Zone (HSZ), located within a southwest-to-northeast oriented band that stretches from west-central to

north-eastern Nevada and Idaho, is noted for abundant high temperature (>100° C) geothermal systems. This is generally attributed to the unique structural setting formed by the transfer of tectonic stresses from the Walker Lane right-lateral strike-slip regime into Basin and Range extension. The resultant faults may be both permeable and preferentially oriented for fluid flow in the present northwest-directed extensional strain field. A handful of structural settings have been found to control the majority of geothermal systems within the Basin and Range province. These settings are a) fault step-overs b) fault terminations c) fault intersections d) accommodation zones. Fault step-overs are the most common geothermal structural setting, controlling ~33% of known geothermal systems within the boundaries of the Great Basin. Hybrids of these settings are often even more accommodating to geothermal system generation.

Though a broad base geologic understanding of geothermal activity is well documented, investigations of individual systems are ongoing. The purpose of this study is to characterize the structural setting controlling secondary permeability at Buffalo Valley hot springs, Lander County, Nevada. This was accomplished through mapping of bedrock and surficial geologic units, at 1:24,000 scale, of eastern Buffalo Valley and west-central Fish Creek mountains. The slip and dilation tendencies of faults mapped proximal to Buf-falo Valley hot springs (BVHS) were assessed to identify faults that may be favorably oriented to form fluid conduits, and temperature surveys, at 2-meter depth, were performed to isolate zones of geothermal upwelling and outflow.

Geologic mapping has revealed that Buffalo Valley’s geothermal system is located within a right-step in the Fish Creek mountains western range-bounding fault. The stepping nature of this fault system has resulted in a diffuse zone of faulting referred to as the Fish Creek Mountains fault zone (FCMFZ). Within the FCMFZ, variability of individual fault-strike orientations result in secondary fault intersections within the larger right step-over. This creates a hybrid fault step-over/ fault intersection structural setting. Slip and dilation tendency calculations, for individual faults, have pinpointed faults preferentially oriented for slip and dilation in the current north-northwest directed extensional regime, however shallow temperature measurements indicate that primary geothermal upwelling is controlled by a fault intersection rather than dilation of an individual fault.

Evaluation of Subsurface Structures Using Hydrothermal Alteration Mineralogy — A Case Study of Olkaria South East FieldMichael M. Mwania • Kenya Electricity Generating Company–KenGen, Naivashamichmwania@gmail.com • mmwania@kengen.co.ke

Keywords: Facies, tecto-stratigraphy, hydrothermal alteration, Logplot, Olkaria, permeabilitySouth East Production area (SEP) is one of prime geothermal field under exploitation for electricity generation within the Great

Olkaria Geothermal Area (GOGA). It is currently under exploitation for geothermal resource to supply steam for the proposed Olkaria VI power plant of 140MWe. The subsurface structural controls in this field are not well understood owing to limited characterization of the system in terms of stratigraphic settings and characteristic hydrothermal alteration mineralogy.

To deduce the subsurface structural controls, analysis for hydrothermal alteration characteristic and assemblages were carried out in three wells; OW-802, OW-803 and OW-804. The hydrothermal alteration in the area depict fairly similar characteristics though intensities differ from one well to another. This is evidenced by the bulk permeability and cumulative water-rock interaction processes, which are apparently controlled by either channelized or diffuse flow characteristics within the system. This paper, therefore presents pertinent information on the characteristic hydrothermal alteration patterns and mineral facies that have been used to define the major subsurface structural controls governing the fluid movement within the system.

Distribution of Hydrothermal Alteration in the Cerritos Colorados Geothermal Field, MexicoD. A. Rocha Ruiz1,2 and R. Hernández Zúñiga2 1Facultad de Ingeniería, Universidad Nacional Autónoma de México, Cd. Universitaria, México D.F.2Inter-American Development Bank (IDB)- Energy Ministry, SENER, México, D.F.david.rochar9@gmail.com • drocha.perge@energia.gob.mx

Keywords: Mexico, Cerritos Colorados, hydrothermal alteration, SWIR reflectance spectroscopy, alteration suite, geochemical distribution, magmatic fluids

The study and ana lysis of rock samples from wells drilled in the Cerritos Colorados geothermal field (Mexico) allowed determining the distribution and zonation of alteration minerals in the system. Reflectance spectroscopy in the short-wave infrared range (SWIR) was used on the samples (cores and cuttings) to identify hydrothermal alteration minerals by comparing their spectra against those given in a US Geological Survey database. The main features used were common absorption peaks, shape of the spectrum, percent

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reflectance and wavelength, which provided guidance to identify mineral suites. The zoning and geochemical distributions of the identified minerals in the system, in general correlated with observed lithology and hydrothermal alteration. As a result, four main alteration associations (argillic, phyllic or sericitic, propylitic and advanced argillic) were defined, which reflected the temperature, pressure, fluid chemistry, and other conditions influencing the presence of characteristic mineral associations.

Structural Controls of the Black Warrior Blind Geothermal System, Washoe-Churchill Counties, Truckee Range, Northwestern Nevada, USAAndrew J. Sadowski and James E. FauldsNevada Bureau of Mines and Geology, University of Nevada, Reno Nevada • andrew.j.sadowski@gmail.com

Keywords: Nevada, Basin and Range, extensional setting, structural controls, Truckee Range, blind geothermal system, fault termination, step over

The Black Warrior geothermal system lies 20 km east of the southern end of Pyramid Lake in the Truckee Range of northwestern Nevada on the Washoe-Churchill county line. It is an amagmatic blind geothermal system, as the region lacks recent (<5 Ma) volcanism and the system lacks hydrothermal surface manifestations (no fumaroles, hot springs, sinter deposits, or high temperature alteration). The system was discovered by shallow temperature gradient drilling (100-600 m, max temp: 128°C) by Phillips Petroleum Company in the 1980s and observed with a 2-m shallow temperature survey circa 2011.

The thermal anomaly resides in a structurally complex zone that has not been previously characterized. Detailed geologic mapping in the area has identified faults and stratigraphic relationships between successive and interfingering Tertiary volcanic sequences that nonconformably overlie Mesozoic plutonic and metamorphic basement. The structural framework is characterized by north-northeast-striking, moderately to steeply west-dipping normal faults that terminate and step in the vicinity of the thermal anomaly. This suggests two possible favorable structural settings: (1) a fault termination of the southeastern rangefront fault with accompanying horse-tail splaying producing an area with abundant closely spaced faults and high fracture permeability; and/or (2) a fault step-over in a broad left-step of the major normal faults, whereby many closely-spaced minor faults provide hard linkage and a zone of high fracture permeability. In either case, the study area lies in a favorable structural setting for geothermal activity and may host a robust geothermal system at depth.

GeophysiCs

Quantifying How Errors in Thermal Conductivity Estimates Affect Geothermal Production ModelsJames “Josh” CrowellUND Geothermal Laboratory, Harold Hamm School of Geology and Geological Engineering, University of North Dakota

Keywords: Thermal conductivity, geothermal, production models, estimatesThermal conductivity can vary significantly within a rock type, sometimes by as much as +/- 50% of published values. The large range

for thermal conductivities can be caused by variations in composition, laminations, impurities, fractures, compaction, grain orientations, temperature, fluid content, and other factors. If published values for thermal conductivity are used in geothermal production models, rather than actual measurements, it is easy to overestimate or under estimate production temperatures over the life of a geothermal well. In a low temperature 3D model of paired geothermal injection and production wells, altering the thermal properties of only one rock layer resulted in production well temperature changes of over 5°C, ranging from +3% to -5% from the baseline production temperature.

Separating Intrinsic From Scattering Seismic Wave Attenuation From Sonic Logs in a Geothermal FieldEvert Durán1, Kasper van Wijk2, Ludmila Adam1, and Irene Wallis3 1University of Auckland, School of Environment, Auckland, New Zealand2University of Auckland, Department of Physics, Auckland, New Zealand • 3Mighty River Power, Rotorua, New Zealand

Keywords: Ngatamariki, attenuation, sonic logging, radiative transfer, quality factorElastic waves attenuate in the earth due to scattering and absorption. The latter can be linked to fluid movement and is of the utmost

importance to the production of a geothermal field. However, it is hard to separate scattering from intrinsic attenuation. Our approach is to use the full elastic waveform from borehole sonic logging, which consists of a coherent part, and incoherent signal produced by the scattered waves (coda). Based on the radiative transfer theory, the coherent energy is affected by the elastic wave attenuation due to both scattering and intrinsic attenuation, while scattering can provide a gain term in the incoherent energy. Here, we quantitatively analyse these intensities to independently estimate the quality factor due to scattering and absorption from full waveform sonic logs in a geothermal field.

Observations and Implications of Magnetotelluric Data for Resolving Stratigraphic Reservoirs Beneath the Black Rock Desert, Utah, USAChristian L. Hardwick1, Rick Allis1, and Philip E. Wannamaker2 • christianhardwick@utah.gov1Utah Geological Survey, Salt Lake City, UT • 2Energy and Geoscience Institute, Salt Lake City, UT

Keywords: Black Rock Desert, magnetotelluric, gravity, resistivity, sedimentary basins, stratigraphic reservoirsMagnetotelluric (MT) data are an integral part of geothermal resource exploration throughout the world. The Black Rock Desert

(BRD), Utah, may be unique, with large datasets of MT soundings and gravity measurements in combination with oil exploration wells

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extending to 5 km depth possessing a variety of geophysical logs, and proven high heat flow in the central part of an underlying basin (temperatures exceeding 240°C at 3 m depth). Wireline geophysical data indicate basin fill signatures of 1 to 10 ohm-m and bedrock signatures of 10 to over 1000 ohm-m. Throughout the BRD, are large variations in lithology and, consequently, resistivity. Massive salt sections, when emplaced in clay-rich basin fill, show resistivities on the order of 100 ohm-m. The upper portions of the 1D, 2D, and 3D resistivity models have reasonable agreement with the wireline data, whereas in the central part of the basin, the deeper por-tions of the wells and the models have disparities that are an order of magnitude different. Possibly the most striking difference is the bottom of the Pavant Butte well where temperatures reach 240°C and in-situ resistivities are 100 ohm-m, but the modeled resistivities are an order of magnitude lower (<10 ohm-m). Possible explanations for this difference are the existence of aligned conductive frac-ture networks deep within the bedrock with a small fraction of crustal fluids in the pore space or differences in the averaging scale of MT data versus downhole wireline data. While emergent signatures of a deeply rooted system are more than likely detected with MT soundings, the signature of our specific target (stratigraphic reservoir) remains elusive.

Three-Dimensional Structural Model Building, Induced Seismicity Analysis, Drilling Analysis, and Reservoir Management at The Geysers Geothermal Field, Northern CaliforniaCraig S. Hartline, Mark A. Walters, and Melinda C. Wright • Calpine Corporation, The Geysers

Keywords: 3D Visualization, 3D model building, induced seismicity, reservoir management, The Geysers Calpine has adopted the use of Paradigm Geophysical SKUA GOCAD software originally developed for the oil and gas industry in

its 3D visualization and model building of The Geysers geothermal reservoir. Structural model building constraints include lithology logs, temperature logs, pressure logs, tracer analysis patterns, heat flow patterns, reservoir history matching, surface geologic maps and seismicity hypocenters available from the Northern California Earthquake Data Center (NCEDC) and Lawrence Berkeley Na-tional Laboratory (LBNL). Recent upgrades to the Paradigm Geophysical SKUA GOCAD 3D seismicity analysis and time animation software have allowed an improved understanding of the spatiotemporal relationships between water injection, induced seismicity, and fracture orientations at The Geysers. This in turn provides a refined understanding of fluid flow paths, fluid boundaries, reservoir heterogeneity and compartmentalization at The Geysers. We can now demonstrate The Geysers reservoir is subdivided by intersecting zones of faulting and fracturing the majority of which are oriented NNW-SSE and ENE-WSW. The 3D structural model development is part of a program to more closely link geoscience, drilling and reservoir engineering, and is anticipated to contribute to reservoir management and induced seismicity mitigation efforts at The Geysers.

Examination of a Site-Specific, Physics-Based Seismic Hazard Analysis, Applied to Surrounding Communities of The Geysers Geothermal Development AreaLawrence Hutchings1, Jean Savy2, Corinne Bachmann1, Oliver Heidbach3, Mamun Miah4, Nate Lindsey1, Ankit Singh1, and Roselyne Laboso5 • ljhutchings@lbl.gov1Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley California • 2Consultant3Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences4University of Mississippi, Oxford, Mississippi • 5Temple University, Philadelphia, Pennsylvania

Keywords: Seismic hazard, The Geysers, Geysers communities, physics-based PSHA, conventional PSHA, induced seismicityWe examine an approach to calculate seismic hazard from induced seismicity based on physics-based computations. This is done

through the formal statistical process commonly referred to as probabilistic seismic hazard analysis (PSHA). We also examine a means to extend computations to a site-specific map for an entire region. Seismic hazard was estimated for a 50 km radius area centered on The Geysers, California. We performed both a traditional PSHA and a physics-based PSHA. We calculated hazard curves at 61 sites in the study area. Ambient noise samples were collected at these sites to modify calculations for site specific information. Further, twenty-three surface geologic units were identified within the study area and site specific calculations were extended to the entire region by interpolation along these geologic units. We first applied the conventional approach by using the actual catalog of the past ten years of earthquakes to estimate the hazard over this period; and thus, the sources of earthquakes were the actual fractures and faults, the rate of occurrence was the actual rate. We then applied an attenuation relation derived with The Geysers data to calculate hazard. In the physics-based approach, the same elements of the PSHA were employed, except physics-based calculations were used to calculate the hazard for the same ten year period. Sources of earthquakes were known faults and random fractures, and the occurrence of earthquakes was determined by geomechanical modeling of the distribution of stress and pressure in the development area. Ground motion was calculated from simulated earthquake ruptures and calculations of wave propagation instead of attenuation relations. We did not distinguish between induced and natural events in either study.

Hazard maps of the number of occurrences of two levels of ground motions over a ten and one year period were developed for values greater than or equal to 0.0014g and 0.1g, respectively. These are generally identified as the minimum level at which humans detect ground shaking and the minimum level at which damage to structures can occur, respectively. For the area within a 50 km radius of The Geysers, the estimated occurrences of the lower level of ground shaking exceeded 8 per year at some locations adjacent to the reservoir development area and diminished to near zero at greater distances. For the same region the estimated occurrences of the 0.1 g or greater was 0.4 per year (approximately once every 2.5 years) adjacent to the reservoir region and diminished to near-zero at greater distances. Remarkably, it was found that calculations by both conventional and physics-based approaches provided very similar results. This is very surprising since they were calculated by completely independent means. Consequently, the calculation of the conventional approach, based on actual data, provides confidence in the physics-based approach used.

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Preliminary Results of a Heat Flow Study of the Williston Basin Using Temporarily Abandoned Oil Wells, Western North DakotaMark R. McDonald1, William D. Gosnold2, and Stephan H. Nordeng2

1North Dakota Geological Survey, Bismarck ND2Department of Geology and Geological Engineering, University of North Dakota, Grand Forks ND

Keywords: Heat flow, Williston Basin, temperature logging, temporarily abandoned wells, North Dakota, memory toolThe North Dakota Geological Survey (NDGS) has embarked on a temperature survey of the Williston Basin, North Dakota. To date,

eleven temporarily abandoned oil and gas wells have been logged using a memory tool equipped with a temperature, gamma-ray, and casing collar locator probe lowered by a slickline. Several methods were used to estimate heat flow at the various locations including calculations based on average laboratory values of thermal conductivity, existing heat flow maps, the Bullard Method, and finding the harmonic mean of thermal conductivity. Although there is general agreement in calculated heat flow values between the various methods listed above, the results are largely predicated upon initial assumptions of either heat flow, thermal conductivity, or both.

While we are confident in the measurements obtained during this study with respect to thermal gradient, additional information on the thermal conductivity of the geologic formations will be required to estimate heat flow within the Williston Basin with better accuracy. Geologic formations can often be differentiated on the basis of “marker” beds, but there can be wide variations in mineral-ogy, lithology, porosity, permeability, density, etc., depending upon depositional environment, depth of burial and secondary processes from one location to another which can profoundly influence thermal conductivity and therefore greatly affect the calculated heat flow.

Magnetic Analysis of Dieng-Batur Geothermal Area Dewi Maria Rahayu and Hilmi El Hafidz Fatahillah • dewi.maria.r@gmail.com • hilmi.el.h@gmail.comGeophysics Sub-Department, Faculty of Mathematics and Science, Universitas Gadjah Mada

Keywords: Alteration, continuation, demagnetization, geothermal, magnetic, structures, reduce to pole, qualitativeResearch has been carried out using a magnetic magnetic method that aims to interpret the structure of the Dieng-Batur Geothermal

area based on upward continuation of both reduce to pole total magnetic field anomaly data and non-reduce to pole total magnetic field anomaly data.

Some 41 points measurements areas were measured using PPM (Proton Precesion Magnetometer) Geotron type G5 models to get the value of the total magnetic field and two points as a base station simultaneously measured using PPM Geometrics type G-586. Measurement data is processed by the diurnal corection and IGRF (international Geomagnetic Reference Field) correction. The data has been used to create contour corrected total magnetic field anomalies involving the upward continuation and reduction to poles.

The result of study showed that in both continuation maps showed two main closures. The total anomaly-field with RTP anomaly showed low total anomaly flanked by high total anomaly, otherwise in total anomaly-field without RTP showed high-total anomaly flanked by low-total anomaly. Both of them indicate two faults zone and geothermal activity effect.

Potentiality of Continuous Measurements Using a Small-Sized Superconducting Gravimeter for Geothermal Reservoir MonitoringMituhiko Sugihara, Kazunari Nawa, Tsuneo Ishido, Nobukazu Soma, and Yuji NishiGeological Survey of Japan, AIST

Keywords: Superconducting gravimeter, gravity monitoring, geothermal reservoir, continuous recording, super hybrid measurements, CCS

Results of continuous gravity measurements carried out at CCS test sites using portable superconducting gravimeters suggest that such gravimeters may be useful for geothermal reservoir monitoring. The most noteworthy advantage is the small initial drift rate, which can be less than 1 microGal/month. It may be possible to detect short term mass redistributions within a geothermal reservoir caused by changes in fluid production or injection rate. One such situation is during the early stages of exploitation when the two-phase zone is expanding rapidly. Another is during field wide shut-ins associated with periodic inspections of the power station. Although such changes have been observed at a few geothermal fields in the past, we anticipate much more success detecting such short term gravity changes using the portable superconducting gravimeter which can detect as small changes as 1 microGal.

injeCtion

Particle Deposition in Porous Media: A ReviewMingjie Cui1,2, Haiyan Lei1,2, and Chuanshan Dai1,2 • leihy@tju.du.cn1Key Laboratory of Efficient Utilization of Low and Medium Grade Energy, MOE, Tianjin University2Geothermal Research &Training Center, Tianjin University, Tianjin, China

Keywords: Geothermal, particle deposition, porous media, reinjectionPlugging of reinjection wells complete in sandstones is a long-standing technical problem for geothermal sustainable development.

The clogging by suspended particles can change pore morphology, leading to formation damage and permeability reduction in the vicinity of the injector, and finally well blockage. This paper reviews particle deposition in porous media, including both experimental

25

and numerical studies, and discusses the visualization research and the simulations done using Lattice Boltzmann Method. These stud-ies will provide directions for future work.

oil and Gas

Co-Produced and Low-Temperature Geothermal Resources in the Williston BasinWill Gosnold, Anna Crowell, Stephan Nordeng, and Michael Mann • University of North Dakota

Keywords: Co-produced, low-temperature, horizontal drilling, organic Rankine cycle, sedimentary basinsThe University of North Dakota has conducted two projects for the Department of Energy to assess and demonstrate the feasibility

of generating electricity using co-produced and low-temperature geothermal resources in the oil and gas producing areas of the Williston Basin in North Dakota. The co-production project was initiated with industry partner, Encore, Inc. in the Eland-Lodgepole field near Dickinson, North Dakota. The field consists of 12 oil and gas wells producing approximately 350 gallons per minute of 100 °C saline water at a central location. Soon after project start, Encore was purchased by Denbury who declined to partner in the demonstration project. The assessment phase of the project produced the key result that the widely distributed wells in the main water producing formations, Madison and Red River, cannot be used to concentrate sufficient quantities of water to generate economic amounts of power. However, the rapid development of multi-well pads in the Bakken and Three Forks has led to localized production of fluids at 120 °C to 130 °C. Our assessment indicates that a distributed network of (organic Rankine cycle) ORC engines in the Bakken fields could offset the need for future construction of fossil fuel power plants and a power grid that will be unneeded when the Bakken plays out. The low-temperature demonstration project is located at a Continental Resources (CLR) water flood site in Bowman County, ND where two CLR water supply wells supply the Davis Water Injection Plant a combined flow of 875 gallons per minute at a tempera-ture of 98 °C. The demonstration project is designed to generate 250 kWh of power using two 125 kW Access Energy ORC engines. The water flood operation at the CLR site adds a new perspective for geothermal development in sedimentary basins in that the water supply wells were completed as kilometer-long open-hole laterals which greatly increases the volume of water that can be produced.

A Basin-Scale Geothermal Assessment of Co-Produced Waters in Oil and Gas Fields: Uinta Basin, Utah, USAChristian L. Hardwick, Hobie W. Willis, and Mark L. Gwynn • christianhardwick@utah.govUtah Geological Survey, Salt Lake City, Utah

Keywords: Uinta Basin, heat flow, direct use, BHT, heat conduction, co-produced water, thermal modelingCo-produced waters from sedimentary basins may represent a significant geothermal resource. This study presents a regional

assessment of the geothermal potential for co-produced waters from oil and gas fields of the Uinta Basin in northeastern Utah using bottom-hole temperature (BHT) and co-produced water data for 776 oil and gas wells along with available lithological information. For 136 of the wells, a BHT correction is applied using Horner and single-BHT correction methods to account for drilling-induced temperature field disturbances. From these wells, a conservative depth-dependent correction of +2.0°C/km was derived and applied to BHTs with insufficient data for other correction methods. Corrected temperatures and typical thermal conductivities are used to calculate thermal gradients and surface heat-flow values for each well. Calculations reveal an average geothermal gradient of about 27°C/km, implying wells producing from depths greater than 2 km in the basin will likely have temperatures greater than 65°C. The average heat-flow value from wells with corrected BHTs is 67 mW/m2. These results are generally typical for gradient and heat-flow values in the Colorado Plateau. Thermal outputs are calculated using well production rates and fluid temperatures. The average ther-mal output is 88 kW per well with a maximum output as high as 10 MW—energy which is currently lost to waste water. The highest output wells are mostly a result of high volumetric production rates. Thermal models for the basin are created using a 3-dimensional, finite-element modeling program (COMSOL Multiphysics 4.4) and are calibrated to corrected well temperatures. Preliminary models reveal an area of approximately 16,000 km2 with temperatures above 75°C at 2 km depth, and an area of 5,500 km2 with temperatures above 150°C at 5 km depth. Co-produced water temperatures in 740 wells are above 50°C and may be suitable for direct-use applica-tions such as greenhouses, space heating, and aquaculture. Binary geothermal power plants generally require a minimum temperature of 140°C to achieve acceptable efficiency and 36 wells (~5%) across the basin meet or exceed such temperatures. The thermal regime and existing infrastructure make the Uinta Basin a candidate for extensive direct-use geothermal applications and possibly binary geothermal power generation.

Produced Water Treatment Using Switchable Polarity Solvent Forward Osmosis (SPS FO) TechnologyDaniel S. Wendt, Gregory L. Mines, Christopher J. Orme, and Aaron D. WilsonIdaho National Laboratory, Idaho Falls, ID

Keywords: Produced water, co-produced water, switchable polarity solvent, forward osmosis, water treatmentSignificant quantities of produced water are brought to the surface during oil and gas production operations. Produced water

generally consists of naturally occurring brine present in the reservoir, but may also contain fracturing fluid or other injection fluids associated with oil and gas recovery operations [1]. The quality of produced water is variable, ranging in salinity similar to that of drinking water to several times more saline than sea water. Various constituents can be contained in produced water from petroleum reservoirs, including dissolved salt, petroleum and other organic compounds, suspended solids, trace elements, bacteria, naturally oc-curring radioactive materials (NORM), and anything injected into the well [2].

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The majority of produced water from hydrocarbon resource development is disposed of by injection. Produced waters that aren’t injected are treated and disposed of in the surface environment, beneficially utilized, or recycled for use in hydraulic fracturing or other oil and gas operations. Lower salinity and better quality produced waters, which are often treated in some way, have many uses, including for irrigation, water for livestock, ecosystem and habitat maintenance, and aquaculture [1].

Cost effective treatment of produced water streams from oil and gas operations can reduce the volume of fluid that otherwise re-quires disposal at a cost to the operator. Switchable Polarity Solvent Forward Osmosis (SPS FO) technology, which could be used for treating produced water streams and reducing overall disposal costs, is currently being developed at the Idaho National Laboratory.

play fairways

Preliminary Ranking of Geothermal Potential in the Cascade and Aleutian and Volcanic Arcs, Part III: Regional Data Review and ModelingMark Coolbaugh1,2, Lisa Shevenell1, Nicholas H. Hinz2, Pete Stelling3, Glenn Melosh4, William Cumming5, Corné Kreemer2, and Maxwell Wilmarth6 1ATLAS Geoscience, Inc., Reno, NV, USA; sereno@dimcom.net • lisas@atlasgeoinc.com2Nevada Bureau of Mines and Geology, UNR, Reno, NV, USA; sereno@dimcom.net • nhinz@unr.edu • kreemer@unr.edu3Western Washington University, Bellingham, WA, USA; pete.stelling@wwu.edu4GEODE, Santa Rosa, CA, USA; gmelosh@gmail.com5Cumming Geoscience, Santa Rosa, CA, USA; wcumming@wcumming.com6Mighty River Power, Rotorua, NZ; maxwell.wilmarth@mightyriver.co.nz

Keywords: Cascade, Aleutian, volcanic, geothermal, potential, structure, arc, power densityAs the third installment in a three-part series, this paper discusses methods of combining regional and local-scale data to predict

geothermal potential at volcanic centers in the Aleutian and Cascade volcanic arcs. Local tectonic and structural settings were the primary drivers for assessing geothermal potential in these models, but the potential impact of new world models for strain style, plate motion, and crustal thickness was also assessed. In the case of strain style and plate motion, geodetically derived estimates of exten-sional and transtensional strain and arc-parallel plate velocities were found to correlate with power density and installed megawatts in producing arc-related geothermal systems. Local issues with global positioning system (GPS) station densities, locked plates, and magma movements increase local uncertainties of the geodetic models, but the observed correlations offer encouragement that with time, improved geodetic models can play an increasing role in geothermal predictions. A positive correlation was also identified be-tween intermediate values of crustal thickness (25-40 km) and installed MWe in volcanic arcs. This relationship might be influenced by anthropogenic factors, because remote island arcs with thin crust and the high altiplano of South America with thick crust have seen relatively little geothermal development, but geologic factors such as uplift rates (high in the Andes), which influence the composition of reservoir host rock, may also exercise an important role.

Local and regional scale data were combined into predictive geothermal models using a play fairway concept with four principal tiers or geologic factors: heat source, permeability, fluid composition, and cap rock. Potential volcanic arc play types of 1) conventional arc systems, 2) strike-slip pull-apart systems, 3) extensional basin systems, and 4) other fault-dominant systems were incorporated into a single play fairway model using weighting factors appropriate to the specific structural setting of each. Subsequent to creation of the fairway models, direct evidence in the form of spring and well temperatures and geothermometry, as well as occurrences of fumaroles and surface mineral deposition (e.g. silica sinter) were used to refine the predictions. Degree-of-exploration was also incorporated by applying negative weights for the lack of positive direct evidence at volcanic centers where exploration was considered to have been significant.

The resulting preliminary fairway and favorability models predict elevated geothermal potential in several clusters of the central to western Aleutian Arc, the largest of which corresponds to the transition from oceanic crust to continental crust. In the Cascades, the best geothermal potential is predicted in the southern half of the arc, where transtensional to extensional tectonic process are more operative and Basin and Range extension overlaps with the active arc.

Integrated Geologic and Geophysical Approach for Establishing Geothermal Play Fairways and Discover-ing Blind Geothermal Systems in the Great Basin Region, Western USA: A Progress ReportJames E. Faulds1, Nicholas H. Hinz1, Mark F. Coolbaugh1,2, Lisa A. Shevenell2, Drew L. Siler3, Craig M. dePolo1, William C. Hammond1, Corné Kreemer1, Gary Oppliger4, Philip E. Wannamaker5, John H. Queen6, and Charles F. Visser7 1Nevada Bureau of Mines and Geology, University of Nevada, Reno NV • 2ATLAS Geosciences Inc., Reno NV3Lawrence Berkeley National Laboratory, Berkeley CA • 4Reno NV5Energy and Geoscience Institute, University of Utah, Salt Lake City UT • 6Hi-Q Geophysical, Inc., Ponca City OK7National Renewable Energy Laboratory, Golden CO

Keywords: Great Basin, Nevada, play fairway, structural setting, geostatistics, geothermal potential mapWe have undertaken an integrated geologic, geochemical, and geophysical study of a broad 240-km-wide, 400-km-long transect

stretching from west-central to eastern Nevada in the Great Basin region of the western USA. The main goal of this study is to pro-duce a comprehensive geothermal potential map that incorporates up to 11 parameters and identifies geothermal play fairways that represent potential blind or hidden geothermal systems. Our new geothermal potential map incorporates: 1) heat flow; 2) geochemistry

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from springs and wells; 3) structural setting; 4) recency of faulting; 5) slip rates on Quaternary faults; 6) regional strain rate; 7) slip and dilation tendency on Quaternary faults; 8) seismologic data; 9) gravity data; 10) magnetotelluric data (where available); and 11) seismic reflection data (primarily from the Carson Sink and Steptoe basins). The transect is respectively anchored on its western and eastern ends by regional 3D modeling of the Carson Sink and Steptoe basins, which will provide more detailed geothermal potential maps of these two promising areas. To date, geological, geochemical, and geophysical data sets have been assembled into an ArcGIS platform and combined into a preliminary predictive geothermal play fairway model using various statistical techniques. The fairway model consists of the following components, each of which are represented in grid-cell format in ArcGIS and combined using specified weights and mathematical operators: 1) structural component of permeability; 2) regional-scale component of permeability; 3) combined permeability, and 4) heat source model. The preliminary model demonstrates that the multiple data sets can be successfully combined into a comprehensive favorability map. An initial evaluation using known geothermal systems as benchmarks to test interpretations indicates that the preliminary modeling has done a good job assigning relative ranks of geothermal potential. However, a major challenge is defining logical relative rankings of each parameter and how best to combine the multiple data sets into the geothermal potential/permeability map. Ongoing feedback and data analysis are in use to revise the grouping and weighting of some parameters in order to develop a more robust, optimized, final model. The final product will incorporate more parameters into a geothermal potential map than any previous effort in the region and may serve as a prototype to develop comprehensive geothermal potential maps for other regions.

Geothermal Play-Fairway Analysis of Washington State ProspectsCorina Forson1, Michael W. Swyer2, Gina M. Schmalzle3, Jessica L. Czajkowski1, Trenton T. Cladouhos2, Nicholas Davatzes4, David K. Norman1, and Ryan A. Cole5 1Washington Division of Geology and Earth Resources, Olympia, WA • 2AltaRock Energy, Inc., Seattle, WA 3BOS Technologies, LLC, Seattle, WA • 4Temple University, EES, Beury Hall, Philadelphia, PA 5Minerals and Geology Management, U.S. Forest Service, Missoula MT

Keywords: Play-Fairway, Washington, Mount St. Helens seismic zone, Wind River valley, Mount Baker, geothermal favorability, heat, permeability, GIS modeling

Analysis of existing geologic, geophysical, and geochemical data revealed areas with elevated heat and permeability, defining three promising plays along the central axis of the magmatic arc of Washington State: Mount St. Helens, Wind River valley, and the southeast flank of Mount Baker. These areas are geothermal ‘fairways’, or locations with high geothermal resource potential based on modeling. This project applies innovative data analyses (Poly3D) in conjunction with methods proven in previous geothermal favor-ability studies (ArcGIS and MATLAB) to extract new value from existing public data. Heat and permeability potential models for each play are weighted using the Analytical Hierarchy Process, and combined to map geothermal resource potential and locations for further data collection at each site. Heat potential is based on: (1) temperature gradients, (2) volcanic vents, (3) Quaternary intrusive rocks, (4) spring temperature, and (5) spring geothermometry. Permeability potential is based on: (1) slip and (2) dilation tendency on mapped and seismic faults (3) maximum shear strain rate, and (4) dilatational strain rate at the surface, (5) modeled fault displacement distribution, and (6) displacement gradient, (7) shear, and (8) tensile fracture density, and (9) local geology and geophysical data. This information is vital for revealing the small scale heat and permeability potential of each study area, locating areas of undiscovered or untapped resources, and reducing the risk and cost involved in greenfield exploration and development. Preliminary analysis of the three play areas shows promise for geothermal development. Uncertainty modeling is underway and the results will guide future exploration plans.

Cerro Prieto, Mexico — A Convective Extensional Geothermal PlayLuis C. A. Gutiérrez-Negrín • l.g.negrin@gmail.com • Geocónsul, SA de CV, CeMIE-Geo, AGM, Morelia, Mich., Mexico

Keywords: Geothermal plays, transform margin, extensional, tectonic setting, explorationThe Cerro Prieto, Mexico, geothermal field lies in a convective geothermal play type located into an extensional (transtensional)

setting, defined by a pull-apart basin in the middle of two strike-slip faults belonging to the San Andreas fault system, which in turn is part of the transform margin between the North America and Pacific plates. The reservoir is of high temperature (250-310°C) and liquid-dominant type with a current production of 41% steam and 59% brine of typical neutral sodium-chloride composition and average of 27,300 ppm of total dissolved solids (TDS). The easternmost wells produce geothermal fluids with lower pH. The steam fraction presents an average of 1.4% in weight of non-condensable gases. The natural recharge to the reservoir is groundwater from a huge, shallow, alluvial aquifer and the Colorado River located to the east. The heat source is a regional thinning of the continental crust producing heat plumes and inferred basic intrusives. Host rocks are Tertiary sandstones interbedded into shales overlying a mainly Cretaceous granitic basement. Reservoir permeability is primary (sandstones matrix for storage) and secondary, with faults driving the geothermal flows. With an installed power capacity of 720 MW (570 MW currently in operation), the field is the second largest worldwide, and has been in production since 1973. There are almost 170 production and injection wells with average depth of 2,400 meters. The field is located at 13 meters above the sea level into a low-relieve topographic framework.

Preliminary Ranking of Geothermal Potential in the Cascade and Aleutian Volcanic Arcs, Part II: Structural — Tectonic Settings of the Volcanic CentersNicholas H. Hinz1, Mark Coolbaugh1,2, Lisa Shevenell2, Glenn Melosh3, William Cumming4, and Pete Stelling5 1Nevada Bureau of Mines and Geology, UNR, Reno NV, USA2ATLAS Geoscience, Inc., Reno NV, USA • 4Cumming Geoscience, Santa Rosa CA, USA

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3GEODE, Santa Rosa, CA USA • 5Western Washington University, Bellingham WA, USAnhinz@unr.edu • lisas@atlasgeoinc.com • sereno@dimcom.netgmelosh@gmail.com • wcumming@wcumming.com • pete.stelling@wwu.edu

Keywords: Cascade, Aleutian, arc, volcano, tectonics, structural settings, geothermal potentialAs part of a Department of Energy funded project on Geothermal Play Fairway Analysis, this paper discusses the methodology

and preliminary results of evaluating local structural and tectonic settings associated with permeability fairways in the Aleutian and Cascade arcs. Specific structural settings coupled with appropriate active strain and complementary stress fields are favorable for both the deep vertical permeability necessary for the roots of hydrothermal systems and the shallow permeability at depths economical for commercial development. Favorable structures include intersections of major faults, pull-aparts along strike-slip faults, step-overs between normal faults, fault terminations of normal or reverse faults, displacement transfer zones, accommodation zones, and dense networks of nascent faults or fault intersections. Some volcanic centers overlap with multiple separate individual or compound struc-tures. Multiple supporting parameters are being collected to help characterize the favorability of these structural settings including strain rates, strain style (.e.g., extensional or compressional), Quaternary fault data, fault orientations, stress data, kinematic linkage of vents, and the degree of certainty for the principle parameters. These data will be combined with other data sets such as geochemistry, presence of active geothermal features, characteristics of magmatism and volcanism, and degree of exploration to produce overarching favorability analysis of the Cascade and Aleutian arcs as discussed in the two companion papers.

Low-Temperature Geothermal Energy Characterization by Play Fairway Analysis for the Appalachian Basin of New York, Pennsylvania and West VirginiaTeresa Jordan2, Erin Camp2, Jared Smith1, Calvin Whealton1, Frank Horowitz1, Jery Stedinger1, Jefferson Tester2, Maria Richards3, Matthew Hornbach3, Zachary Frone3, Rahmi Bolat3, Brian Anderson4, Xiaoning He 4, and Kelydra Welcker4 1Cornell University School of Civil and Environmental Engineering, Ithaca, NY2Cornell University Dept. Earth & Atmospheric Sciences, Ithaca, NY3SMU Geothermal Laboratory, Huffington Dept. of Earth Sciences, Dallas, TX 4West Virginia University, Dept. Chemical Engineering, Morgantown, WVtej1@cornell.edu • mrichard@smu.edu

Keywords: Play Fairway Analysis, geothermal direct-use, low temperature, reservoir analysis, BHT, geothermal energy utilizationDirect-use of geothermal energy in the Appalachian Basin has the potential to offset a considerable amount of fossil-fuel-supplied

heat. Currently, the risks associated with potential projects are broadly unknown. This project aims to assess the risks of developing direct-use geothermal energy in the Appalachian Basin through: 1) organization of data into Play Fairways, 2) quantification of geological, thermal, and utilization characteristics and uncertainty, 3) estimation of region-wide levelized cost of direct-use heat, and 4) identifica-tion of additional data collection needs beyond what are currently available. Successful completion of this project will provide a tool to aid decision makers in selecting areas that seem initially favorable to low-temperature geothermal projects. As it is only 6 months into the project, the final analysis of risk factors and resulting maps showing the most favorable areas with low-temperature geothermal resources for direct-use-heat applications in the Appalachian Basin of New York, Pennsylvania, and West Virginia will be presented at the GRC Annual meeting and published as part of this Department of Energy Project DE-EE0006726 Final Report in Fall of 2015.

Integration of Data in a Play Fairway Analysis of Geothermal Potential Across the State of HawaiiNicole Lautze1, Donald Thomas1, Nicholas Hinz2, Neil Frazer1, Garrett Ito1, David Waller1, Hannah Schuchmann1, and Mark Brady3 1University of Hawaii • 2University of Nevada, Reno • 3Hawaii Department of Land & Natural Resources

Keywords: Geothermal, Hawaii, Play Fairway, maps, volcano, gravity, water, probability, geostatistics The execution of this project can be divided into three main tasks: (1) the compilation of both historical and current geologic,

geophysical, and geochemical data for Hawaii that is relevant to geothermal resources into a single Geographic Information System (GIS) project; (2) the systematic analysis and ranking of these datasets in terms of their relevance to the three primary properties of a viable geothermal resource: heat (H), fluid (F), and permeability (P); (3) the application of geostatistical methods to the ranked data to produce Play Fairway (PF) maps for Hawaii’s. Here, we summarize the project methodology and present preliminary maps that highlight both high prospect areas as well as areas that lack enough data to make an adequate assessment. We suggest a path for future exploration activities in Hawaii, and discuss how this method of analysis can be adapted to other regions and other types of resources.

Geothermal Play Fairway Analysis of Potential Geothermal Resources in NE California, NW Nevada, and Southern Oregon: A Transition between Extension-Hosted and Volcanically-Hosted Geothermal FieldsJ. S. McClain1, Patrick Dobson2, Carolyn Cantwell1, Mark Conrad2, Colin Ferguson1, Andrew Fowler1, Erika Gasperikova2, William Glassley1, Samuel Hawkes1, Peter Schiffman1, Drew Siler2, Nicolas Spycher2, Craig Ulrich2, Yingqi Zhang2, and Robert Zierenberg1

1University of California, Davis • 2Lawrence Berkeley National Laboratory

Keywords: Play Fairway analysis, geothermal resource assessment, Surprise Valley, exploration

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Play Fairway analysis is a powerful tool in the petroleum industry for reducing drilling risk. It relies on general models for sedi-mentary depositional systems (at the basin scale) and applies all available data to identify weighted combinations of characteristics that can be used to predict the locations where drilling is likely to lead to successful fossil fuel extraction.

This project represents an effort to apply the same approach to geothermal resource exploration and assessment. Geothermal systems do not have the same level of basin-wide coherence as oil- or gas-bearing formations, but rather are often controlled by very localized characteristics. However, all geothermal fields must include elements of a heat source, fluids, and a permeability structure that may vary systemically over a region. This is where Geothermal Play Fairway Analysis (GPFA) may be a valuable tool. To this end, we are applying GPFA to a region where both volcanically and extensionally hosted systems are known, and examine the nature of the transition between these different geothermal play types.

Adaptation of a Petroleum Exploration Tool to Geothermal Exploration: Preliminary Play Fairway Model of Tularosa Basin, New Mexico, and TexasGregory D. Nash1 and Carlon R. Bennett2 1Energy & Geoscience Institute at the University of Utah • 2Ruby Mountain Inc.

Keywords: Geothermal exploration, Tularosa Basin, play fairway analysis, GIS, exploration modelingInvestment in geothermal development has not been optimal due to inherent risk, but now risk can be lowered through the proper

application of play fairway analysis (PFA) targeting the best geothermal reserves within a region. Both knowledge-based and data-driven models have been tested in this regard, however, neither method has gained significant industry attention. In this study we apply a deterministic method that has been widely used by the petroleum industry to reduce exploration risk through regional analysis for play identification. We have adapted this logic for geothermal application and completed a preliminary PFA for the Tularosa Basin in New Mexico and Texas. Data is critical for PFA, and although there is never enough, especially in underexplored regions such as this, we believe that it is possible to collect adequate data in most areas with geothermal potential for successful PFA application.

Hydrogeologic Windows: Detection of Blind and Traditional Geothermal Play Fairways in Southwestern New Mexico Using Conservative Element Concentrations and Advective-Diffusive Solute Transport Mark Person1, Shari Kelley2, Richard Kelley3, Satish Karra3, Dylan Harp3, James Witcher4, Jeffrey Bielicki5, Glenn Sutula5, Richard Middleton3, and Jeff D. Pepin1 1New Mexico Institute of Mining and Technology, Socorro NM2New Mexico Bureau of Geology and Mineral Resources, Socorro NM • 3Los Alamos National Laboratory, Los Alamos NM4Witcher and Associates, Las Cruces NM • 5The Ohio State University, Columbus OH

Keywords: Play fairway, hydrogeologic windows, conservative element tracers, advection-diffusion, modelingWe combine trace element geochemistry and hydrologic tracer transport analysis to identify geothermal upflow zones within

southwestern New Mexico. We analyzed about 1400-4000 wells with lithium and boron chemical analyses. Most of the geothermal waters had elevated lithium and boron concentrations (> 0.5 mg/l) that weakly correlate with reservoir temperatures. We used avail-able water-table measurements to construct water-table maps and calculate groundwater flow directions. We used an “upwinding” ap-proach to track mathematical particles through the flow field within the shallow aquifer system. Areas where particles with high tracer concentrations pass wells with low tracer concentrations may indicate the presence of a geothermal upflow zone. The approach was applied to the southern Albuquerque Basin near San Acacia and the southern Engle Basin near Truth or Consequences, NM. Although our approach revealed a potential geothermal upflow zone at Indian Wells spring near San Acacia NM, additional work is needed to refine the methodology. A multiple realization-based methodology for locating tracer sources was also developed. In this method, an advection-diffusion equation was solved for eighty realizations of different source locations in the Socorro-La Jencia Basin area. By comparing simulated tracer concentrations to measured values, a source-likelihood map was drawn, and the tentative source locations were identified. The region of high heat flow within the Socorro-La Jencia Basin at the base of Socorro Peak was found to have a lo-cal minimum of the root mean squared error of simulated minus observed normalized lithium concentrations. This suggests that our approach can identify geothermal up flow zones.

Snake River Plain Play Fairway Analysis – Phase 1 Report John W. Shervais1, Jonathan M. Glen2, Lee M. Liberty3, Patrick Dobson4, Erika Gasperikova4, Eric Sonnenthal4, Charles Visser5, Dennis Nielson6, Sabodh Garg7, James P. Evans1, Drew Siler4, Jacob DeAngelo2, Noah Athens8, and Erick Burns8

1Department of Geology, Utah State University, Logan UT • 2US Geological Survey, Menlo Park CA3Center for Geophysical Investigation of the Shallow Subsurface, Boise State University, Boise ID4Lawrence Berkeley National Laboratory, Berkeley CA • 5National Renewable Energy Laboratory, Golden CO 6DOSECC Exploration Services, LLC., Salt Lake City UT • 7Leidos, Inc., San Diego CA • 8US Geological Survey, Portland OR

Keywords: Snake River Plain, geothermal exploration, Play Fairway Analysis, GIS, Idaho The Snake River volcanic province (SRP) overlies a thermal anomaly that extends deep into the mantle; it represents one of the

highest heat flow provinces in North America. Our goals for this Phase 1 study are to: (1) adapt the methodology of Play Fairway Analysis for geothermal exploration to create a formal basis for its application to geothermal systems, (2) assemble relevant data for the SRP from publicly available and private sources, and (3) build a geothermal play fairway model for the SRP and identify the most promising plays, using software tools that are standard in the petroleum industry. The success of play fairway analysis in geothermal

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exploration depends critically on defining a systematic methodology that is grounded in theory (as developed within the petroleum industry over the last two decades) and within the geologic and hydrologic framework of real geothermal systems.

Our preliminary assessment of the data suggests that important undiscovered geothermal resources may be located in several areas of the SRP, including the western SRP (associated with buried lineaments defined by gravity or magnetic anomalies, and capped by extensive deposits of lacustrine sediment), at lineament intersections in the central SRP (along the Banbury-Hagerman trend NW of Twin Falls, and along the northern margin of the Mt Bennett Hills-Camas Prairie area), and along the margins of the eastern SRP. Ad-ditional high temperature resources are likely associated with rhyolite domes and crypto-domes in the eastern SRP, but are masked by shallow groundwater flow leading to low upper crustal heat flow values. These blind resources may be exploitable with existing deep drilling technology. Groundwater modeling planned for later phases of the PFA project will address whether temperatures at viable producing depths are sufficient to support electricity production.

Preliminary Ranking of Geothermal Potential in the Cascade and Aleutian Volcanic Arcs, Part I: Data CollectionLisa Shevenell1, Mark Coolbaugh1,2, Nicholas H. Hinz2, Pete Stelling3, Glenn Melosh4, William Cumming5, and Corné Kreemer2

1ATLAS Geoscience, Inc., Reno NV, USA • 2Nevada Bureau of Mines and Geology, UNR, Reno NV, USA3Western Washington University, Bellingham WA, USA • 4GEODE, Santa Rosa CA, USA5Cumming Geoscience, Santa Rosa CA, USA lisas@atlasgeoinc.com • sereno@dimcom.net • nhinz@unr.edu • kreemer@unr.edu • pete.stelling@wwu.edugmelosh@gmail.com • wcumming@wcumming.com

Keywords: Cascade, Aleutian, volcanic, geothermal, potential, structure, databaseAs part of a DOE funded project on Geothermal Play Fairway Analysis, a geothermal assessment of volcanic centers in the Cas-

cade and Aleutian volcanic arcs is being conducted that includes a large data gathering effort discussed in this paper, and a statistical modeling effort to qualitatively rank the geothermal potential of individual VCs in these two US arcs, discussed in a second companion paper. The data compiled from the Cascades and Aleutians are compared to geologic, geochemical and geophysical information from productive volcanic arc centers in the other parts of the world. Seven other volcanic arc segments from around the globe are used in this comparative study. Preliminary findings from data evaluation indicate that there are systematic changes in structural setting, from an extensional influence south of Mt. Hood (in part due to encroachment of the back arc in the southern half) to more compressional north of Mt. Hood. Comparison with productive geothermal fields around the world shows that large fumarolic areas are associated with most >240°C power-producing geothermal systems outside the US arcs (e.g., Kamojang, Indonesia, among others), whereas there is a general absence of large fumarolic areas in the Cascades and Aleutian arcs, aside from of the Lassen volcano area. As a result, fewer deep, successful wells have been drilled in the US in the Cascades and Aleutians, whereas there are many producing wells associated with fumarolic volcanic centers outside the US. Few high temperature (>200°C) systems are known in the US arcs (e.g., Newberry), and there is no direct evidence to date for very high temperature (>300°C) geothermal systems, whereas there are 21 such known systems in other volcanic arcs of the world (e.g., Silangkitang and Lahendong, Indonesia; Hachijojima and Matsukawa, Japan; Amiata, Italy; Los Azufres, Mexico, to name a few).

Play Fairway Analysis of the Central Cascades Arc-Backarc Regime, Oregon: Preliminary IndicationsPhilip E. Wannamaker1, Andrew J. Meigs2, B. Mack Kennedy3, Joseph N. Moore1, Eric L. Sonnenthal3, Virginie Maris1, and John D. Trimble2 • pewanna@egi.utah.edu1University of Utah/EGI, Salt Lake City UT2Oregon State University, College of Earth, Ocean and Atmospheric Sciences, Corvallis OR3Lawrence Berkeley National Laboratory, Center for Isotope Geochemistry, Berkeley CA

Keywords: Play Fairway Analysis, geothermal exploration, Cascades, andesitic volcanism, rift volcanism, magnetotellurics, LiDAR, geothermometry

We are assessing the geothermal potential including possible blind systems of the Central Cascades arc-backarc regime of central Oregon through a Play Fairway Analysis (PFA) of existing geoscientific data. A PFA working model is adopted where MT low resis-tivity upwellings suggesting geothermal fluids may coincide with dilatent geological structural settings and observed thermal fluids with deep high-temperature contributions. A challenge in the Central Cascades region is to make useful Play assessments in the face of sparse data coverage. Magnetotelluric (MT) data from the relatively dense EMSLAB transect combined with regional Earthscope stations have undergone 3D inversion using a new edge finite element formulation. Inversion shows that low resistivity upwellings are associated with known geothermal areas Breitenbush and Kahneeta Hot Springs in the Mount Jefferson area, as well as others with no surface manifestations. At Earthscope sampling scales, several low-resistivity lineaments in the deep crust project from the east to the Cascades, most prominently perhaps beneath Three Sisters. Structural geology analysis facilitated by growing LiDAR coverage is revealing numerous new faults confirming that seemingly regional NW-SE fault trends intersect N-S, Cascades graben-related faults in areas of known hot springs including Breitenbush. Major element geochemical modeling of high-chloride thermal springs west of Three Sisters using Geo-T analytical software implies subsurface equilibration temperatures in the 130-140oC range. Subsurface temperatures and deep source contributions will be refined using ToughReact reactive transport analysis including isotopic data. To date, results appear consistent with our PFA working model described above.

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Play Fairway Analysis of the Eastern Great Basin Extensional Regime, Utah: Preliminary IndicationsPhilip E. Wannamaker1, Joseph N. Moore1, Kristine L. Pankow2, Stuart D. Simmons1, Gregory D. Nash1, Virginie Maris1, Chase Batchelor2, and Christian L. Hardwick3 • pewanna@egi.utah.edu1University of Utah/EGI, Salt Lake City UT • 2University of Utah, Dept of Geology & Geophysics, Salt Lake City UT3Utah Geological Survey, Salt Lake City UT

Keywords: Play Fairway Analysis, geothermal exploration, Great Basin, rift volcanism, magnetotellurics, seismicity, geothermometry

We are assessing the geothermal potential including possible blind systems of the Eastern Great Basin extensional regime of western Utah through a Play Fairway Analysis (PFA) of existing geoscientific data. A PFA working model is adopted where magnetotelluric (MT) low resistivity upwellings suggesting geothermal fluids may coincide with dilatent geological structural settings and observed thermal fluids with deep high-temperature contributions. Unique to this setting is the superposition of active rifting with a N-S strike over E-W oriented belts of mid-Cenozoic plutonic rocks and possible NE-SW Precambrian shear trends. Data from ~470 high-quality MT sites have been undergoing 3D inversion using a new edge finite element formulation. Inversions show that several low resistivity upwellings project in the vicinity of Crater Bench, central Sevier Desert, Cove Fort, and east flank of the northern Mineral Mountains. The former three have known thermal expressions but the latter has no such association although it is along strike to the north of the Crater Knoll-Red Knoll Quaternary eruptions. There is a strong suggestion of control of resistivity structure by ENE-oriented structural trends possibly reactivated in E-W rifting. Reanalysis of seismicity shows that both swarm and non-swarm earthquake clusters locate in close proximity to the low resistivity upwellings near Cove Fort and the northern Mineral Mountains, while there is no seismic signature near the upwelling in the central Sevier Desert. Structural geology analysis based upon compilation of mapping, gravity and high-resolution (5 m often) DEM data has identified thirty-five areas of interest within and near the project fairway representing geometries that can produce critical stresses for dilatency, some of which overlap with MT structures. Major element geochemistry of thermal waters is dominated by chloride and sulphate compositions. Silica geothermometry values correspond well with direct reservoir temperatures, but the somewhat higher Na-K inferred temperatures may reflect deeper basement equilibration. Produced fluid compositions often are not compatible solely with the reservoir rocks of production, and imply substantially larger rock volumes are contributing. Also correlated with reservoir temperature are 3He (R/Ra) values, indicating that magmatic input is associated with convective flow. To date, results appear consistent with our PFA working model described above.

power plant

Evaluation of Inflow Radial Turbo Expander Field Performance for a 25 MW Geothermal Organic Rankine Cycle TrainReza Agahi and Felix Mohr • Atlas Copco Gas and Process

Keywords: Inflow radial turbine, turboexpander, Organic Rankine Cycle (ORC), isentropic efficiency, variable inlet guide vanes, brine, power plant design, Turkey, Pamukuren

The first phase of a geothermal Organic Rankine Cycle (ORC) power plant was commissioned in October, 2013. The electrical power production capacity of this plant will be in excess of 100 MW when phases two and three are completed in 2015.

This geothermal ORC power plant was optimized with normal butane as the working fluid using an inflow radial turbine. The first phase, with nominal power of 45 MW consisted of two power trains. Each power train has a nominal capacity of 22.5 MW electrical power output.

In this paper we present the geothermal resource design conditions, the thermodynamic issues for the choice of working fluid, field performance of the inflow radial turbine and comparison with the expected performance.

Use of a Waste Heat Boiler to Capture Energy From Flammable Noncondensable Gas at Geothermal Power PlantsJohn Avery1, Brian Benn1, Kenneth E. McIntush2, Darryl Mamrosh2, and Carrie Beitler2 1Calpine Corporation, The Geysers Power Plant, Middletown, CA • 2Trimeric Corporation, Buda, TXjohn.avery@calpine.com • brian.benn@calpine.com • ken.mcintush@trimeric.com • darryl.mamrosh@trimeric.com carrie.beitler@trimeric.com

Keywords: Noncondensable gas, NCG, H2S abatement, burn/scrub, waste heat boiler, WHB, waste heat recovery, sulfuric acid, corrosion

A study was performed to determine if a waste heat boiler could economically capture energy from a flammable noncondensable gas stream at a geothermal power plant. Vendors of combustion and waste heat boiler equipment were contacted to gain purchased equipment costs. Operating costs related to the waste heat boiler were estimated. The economics of H2S abatement were then evaluated both with and without waste heat recovery to determine the cost effectiveness of the waste heat recovery boiler. Additional information was learned from the vendors regarding the various types of waste heat boilers that could be used in this application, as well as how the boilers are integrated with the upstream combustion device. Different options for the materials of construction of the combustion unit and waste heat boiler were also investigated to help mitigate the potential for corrosion from sulfuric acid condensation. The economic and design details for the waste heat boiler as an integral part of a burn/scrub H2S abatement process are discussed in this

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paper. For the application being considered, the waste heat boiler was estimated to have a payback of 25 to 34 months when used as an integral part of the burn/scrub H2S abatement system. The waste heat boiler economics were also evaluated for the case where a different H2S abatement technology was used (i.e., Stretford) such that the combustion unit and boiler could be located after the H2S had already been removed; in this scenario, the payback on the waste heat boiler was about 12 to 17 months due to the slightly higher steam recovery and a less expensive waste heat boiler. For the cases considered, the waste heat boiler would generate steam equivalent to about 2%-3% of the inlet flow of geothermal steam.

Tubular Biofilm Reactor for Hydrogen Sulphide Removal From Geothermal Cooling WaterEmily Bierre1 and Rob Fullerton2 • milly@jrgenergy.com • rob.fullerton@beca.com1JRG Energy Ltd, New Zealand • 2Beca Ltd, New Zealand

Keywords: Biofilm, tubular bioreactor, hydrogen sulphide oxidizing bacteria, geothermal power station, cooling water, H2S abatement

The Wairakei geothermal power station situated in Taupo in the North Island of New Zealand was commissioned in 1958. Cool-ing water and geothermal steam condensate containing hydrogen sulphide is discharged from the power station to the Waikato River. Environmental concerns over sulphide aquatic toxicity in the river were key considerations during the discharge permit conditions renewal process which ran from 2001 to 2007. New discharge limits for the power station were proposed by Contact Energy and came into effect in August 2012, requiring the mass emission of hydrogen sulphide in the cooling water to be reduced from current levels of approximately 10,300kg/week to 2,800kg/week, with a further reduction to 630kg/week from 2016. This required a hydrogen sul-phide concentration reduction from 1000mg/m3 to less than 60mg/m3 in a cooling water flow of 17m3/s. An innovative tubular biofilm reactor was developed, leading to construction of a full scale plant in 2012. The full scale bioreactor consists of 1890 parallel 100mm diameter x 200m length pipes with a total length of 378km, believed to be the largest tubular biofilm reactor in the world at the time of construction. The paper backgrounds the pilot plant investigations, development of design parameters, construction of the full scale bioreactor and reviews performance since commissioning in August 2012.

Turboden, a Presentation of Recent Worldwide Developments and the Latest Technical Solutions for Large-Scale Geothermal ORC Power-PlantsJoseph Bonafin1, Clotilde Rossi di Schio1, and Andrea Duvia2 • a.duvia@gammelduvia.it • info@turboden.it1Turboden, Brescia, Italy • 2Gammel Duvia Engineering Srl, Torino, Italy

Keywords: ORC, geothermal, binary plant, double pressure, hybrid cooling systemAfter our successful experience with three 5 MW geothermal power plants in Bavaria, and an upcoming 4th plant, Turboden has

been enlarging its plants to up to 25MW electric power. A 25MW Turboden plant has been recently designed for the Aydin reservoir in Turkey. This paper focus on the technology of this plant, particularly describing the type of thermodynamic cycle, and the optimi-zation drivers. The importance of configuration selected for optimized efficiency, and the design of key components like turbine and heat exchangers has been highlighted.

Geothermal Binary Power Plants at Raft River, San Emidio, and Neal Hot Springs: Part 1 — Plant Descriptions and Design Performance ComparisonRonald DiPippo1, Ph.D., and Kevin Kitz, P.E.2 • rondipippo@comcast.net • kkitz@usgeothermal.com1Renewable Energy Consultant, South Dartmouth, MA2 Vice President-Project Development, U.S. Geothermal Inc., Boise, Idaho

Keywords: Geothermal power plant, Raft River, San Emidio, Neal Hot Springs, binary cycle, organic Rankine cycle, sub-critical, supercritical, thermal efficiency, exergy, utilization efficiency, specific power, R134a, isopentane

U.S. Geothermal Inc. built and operates the Raft River (Idaho), San Emidio (Nevada) and Neal Hot Springs (Oregon) geothermal organic Rankine cycle binary power plants. All of them use similar moderate-temperature geofluids pumped from wells and the same 280°F brine inlet design temperature. Raft River uses a recuperated subcritical isopentane cycle, while San Emidio and Neal Hot Springs employ R134a in cycles with supercritical turbine inlet pressures. Neal Hot Springs uses an air-cooled condenser, while the other two are water-cooled. The theoretical thermodynamic performance and net generation of these three power plants with very similar geothermal design conditions are compared. The comparison is made for the design conditions. We show that at the 280°F brine design temperature of the three plants, the supercritical cycle produces more power per pound of brine than the subcritical cycle does. However, while most of this difference is related to the inherent characteristics of the cycles, such as the amount of heat able to be extracted from the brine by the cycle, there are some differences related to economic choices made at the time the plants were built, such as the condenser approach temperature to the sink temperature (wet-bulb or dry-bulb design temperature).

Evaluation and Optimization of the Cerro Prieto Geothermal Field Steam Transportation Network Efficiency — Estimation of Heat Losses From Pipe FittingsAlfonso García-Gutiérrez1, Rosember Ovando-Castelar1, Juan I. Martínez-Estrella1, Ismael Canchola-Félix2, and Paul V. Jacobo-Galván2 • agg@iie.org.mx1Instituto de Investigaciones Eléctricas, Cuernavaca, Mor., México2Comisión Federal de Electricidad, Residencia Cerro Prieto, Mexicali-Pascualitos-Pescaderos, B.C., México

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Keywords: Cerro Prieto geothermal field, fittings, pipeline network, heat loss, finite element modelingThe present work is part of a much larger project aimed at improving the performance of the Cerro Prieto Geothermal Field (CPGF)

steam gathering network by reducing heat losses and improving the efficiency of energy utilization. During evaluation the efficiency of steam transport in the network, pipe fittings were identified to represent an important source of heat loss since, unlike the pipes, they are not thermally insulated. In this work, a methodology for quantifying heat loss in the various fitting types installed in the CPGF steam gathering network is described. This methodology is based on the geometry of the different fittings, and the basic equations for convective heat transfer and fin efficiency calculations. The results were compared with field surface temperature measurements on fittings, carried out with infrared technology and with modeling results of typical fittings using commercially-available software based on the FEM method to solve the corresponding heat transfer equations.

Predictive Functional Control Applied in Vapor Temperature Control of Organic Rankine Cycle SystemDaxing Huang, Zhigang Wang, and Wencheng Fu • School of Electrical Engineering, Tianjin University of Technology

Keywords: PFC, ORC, waste heat recovery, time delay, vapor temperatureA novel control algorithm called Predictive Functional Control (PFC) is applied to vapor temperature control at the outlet of evapo-

rator of organic Rankine cycle (ORC) system. The simulation results show that the PFC algorithm not only can obtain effective control performance, but also has less online computation time, satisfactory robustness properties and disturbance rejection performance.

Rerouting the Condensate in an ORC Geothermal Power PlantMustafa Inanli1 and Pal Valdimarsson2 1Project Manager, Atlas Copco Gas and Process Division, Tuzla-Istanbul, Turkiye2Manager R&D ORC Power Solutions, Atlas Copco Gas and Process Division, Reykjavik, Iceland

Keywords: ORC, Organic Rankine Cycle, power plant, steam condensate, power cycle, optimization, geothermalUtilization of medium and low enthalpy geothermal resources have been on the rise with the advent of ORC Geothermal Powe

Plants. Mostly these plants intake brine and steam, that are separated at the wellhead, via separate pipelines into the Brine and Steam Evaporators where heat is transfered from the resource to the motive fluid in the ORC Cycle. After the transfer of heat to the motive fluid through the Steam Evaporator, steam turns into condensate and NCG at the Evaporator end. Later the condendate is either tied to the Reinjection piping or to brine line line between Brine Evaporator outlet and Preheater inlet.

This paper argues the alternative to route this condensate flow before the Brine Evaporator inlet, not only to utilize the heat and mass flow of condensate at the Brine Evaporator but also help the mitigation of scaling at the brine evaporator tubes diluting the brine, and also lowering the pH of the composition.

The energy gain was calculated utilizing the correction curves of the ORC plant, it was found out that the condensate re-routing moves the plant closer to the optimal operating condition, and these calculations indicate that almost half of the expected gain is not due to increased heat input, but because of better plant efficiency closer to the optimum operating point.

Coso Case Study: 22 Years of Reliable Sulfur RemovalMark Kolar1, Steve Osgood2, and William Echt2 • 1Terra-Gen Power, LLC • 2Merichem Company

Keywords: Sulfur recovery, H2S removal, geothermal power, steam power, gas treating, unit operations, operating history, case study, electric power generation, renewable power

Terra-Gen Power operates a 300-megawatt electric generation facility at the China Lake Naval Weapons Station. The geothermal steam wells at the Coso facility provide a renewable source of energy. The non-condensable vapors from the steam well cannot be vented to the atmosphere until small amounts of hydrogen sulfide (H2S) are removed. The LO-CAT® process has been successfully removing H2S at this site for the past twenty-two years. Using LO-CAT technology greatly reduced sulfur emission exceedances and operating costs relative to previously used technologies.

The facility has three LO-CAT units. This paper analyzes over 500 hundred data points obtained during a 22-year period and cal-culates the current cost of removing sulfur at this facility. It also discusses typical operational issues including routine operator duties, H2S removal efficiency and long-term unit reliability (planned and unplanned shutdowns). The paper also explains how the solid sulfur product is used in agricultural applications.

Thrust Bearing Load Observations in Deep Well Enclosed Lineshaft PumpsChris Reede1, Dr. Haris Doumanidis2, Dr. Matteo Aureli3, and Marie Curie2 1Ormat Technologies • 2Mechanical Engineering, Khalifa University, Abu Dhabi, UAE • 3University of Nevada, Reno

Keywords: Well pumps, lineshaft pumps, axial thrust, geothermal production pumps, relative stretchThis paper reports the experimental observations of thrust bearing load on deeply set enclosed lineshaft pumps operating at various

shaft speeds. In an effort to validate the accuracy of techniques commonly used to estimate such loads, a load cell was installed between the lineshaft connection and the motor thrust bearing of two identical make and model pumps. The first pump operated with an open lineshaft in the manufacturer’s test lab and the second pump operated in the field with an enclosed lineshaft. The load cell allowed for real-time online measurement of impeller down-thrust encountered on the surface. The thrust measurements were normalized into thrust coefficients and plotted on curves, also known as Kt curves, for various shaft speeds. At lower speeds, it is observed that both the lab pump and field pump Kt curves are in agreement. However, the curves begin to diverge as shaft speed is increased above 1,600 RPM.

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More specifically, Kt curves measured in the field at 1,320 RPM closely followed those measured in the lab, while Kt curves taken in the field at 2,200 RPM were up to 58% lower than the lab measured curves. The experimental data indicate that motor thrust bearings on pumps operating at the usual speed of 1,800 RPM may be loaded significantly less than expected. As a consequence, the impeller relative movement, with respect to pump bowls, may be significantly less than expected. Overall, the data represent a comparison between a well-established lab-tested Kt curve and the Kt curve of a single pump running in the field. Repeatability of the findings needs to be further validated through testing of additional field pumps. Further modeling is also necessary to understand and model the up-thrust mechanisms present in the enclosing tube. Such further validation is expected to highlight general conclusions, allowing for the formulation of useful correlations which account for thrust error. Such correlations will allow operators of similar pumps to better determine motor thrust bearing loads and impeller movement to ultimately increase the production of fluid on the surface.

Design and Evaluation of Geothermal Steam Separators: A Review of the State of ArtFernando Rivas-Cruz, Alfonso García-Gutiérrez, Juan I. Martínez-Estrella, and Ángel A. Ortiz-Bolaños Instituto de Investigaciones Eléctricas, Cuernavaca, Mor., México • fernando.rivas@iie.org.mx

Keywords: Steam separators, design, evaluation, software, Cerro Prieto Geothermal FieldA compilation, review and analysis of the current “state of art” of different theoretical and practical aspects on the design and

evaluation of geothermal steam separators, up to 2014, is presented in this paper. In addition, various computational work tools for designing and evaluating the behavior of geothermal steam separators are included. Most of these programs are based on the theory Lazalde-Crabtree to validate its operation, which is fundamental and applicable reference work for this end. The main goal of this work is to review the background for the development of a computational tool which can be used to design of new equipment and to evaluate the current performance of existing steam separators which have been under operation for a long time, particularly in the Cerro Prieto Geothermal Field (CPGF), México.

Displaced Exergy: The Valuation of Thermal PowerPaul Shurtleff1 and William Harvey2 • 1 POWER Engineers • 2 Reykjavik University

Keywords: Exergy, low temperature, district heating, cogeneration, binary, geothermalConventional exergy analysis is a useful tool to compare the relative efficiency of cycles harnessing geothermal fluids of different

fluid properties, as well as to assess the power generation potential of production well flows and power plant process side streams. These side streams could be fluid flows re-injected to the reservoir or low enthalpy fluids discharged from the power generation pro-cess. Exergy analysis is also a valuable tool to assess the potentials for improvement of a cycle or plant component. However, exergy analysis on power generation projects has the potential to overlook the value of the process streams and the potential contribution that they can make when the same system is analyzed from a more holistic perspective. This paper discusses the concept of “displaced exergy,” where improved matching of a stream’s utilization to local demands and the prevailing energy resources is shown to result in better conversion efficiencies than conventional exergy analysis would indicate is possible. When viewing projects through this proposed perspective, geothermal plants with flexibility in generating both thermal and electrical energy can achieve much higher ef-fective efficiencies than a conventional exergy analysis would indicate. A higher effective efficiency using displaced exergetic analysis could be possible in geographic locations where fossil fuels are widely used for thermal demands, and where the fossil fuel thermal generation could be substituted by utilizing geothermal fluids.

Stillwater Hybrid Geo-Solar Power Plant Optimization AnalysesDaniel S. Wendt1, Gregory L. Mines1, Craig S. Turchi2, Guangdong Zhu2, Sander Cohan3, Lorenzo Angelini3, Fabrizio Bizzarri4, Daniele Consoli4, and Alessio De Marzo4 1Idaho National Laboratory, Idaho Falls ID • 2National Renewable Energy Laboratory, Golden CO3Enel Green Power North America, Andover MA • 4Enel Green Power — Innovation Div., Rome IT

Keywords: Hybrid geothermal solar thermal power plant, air-cooled binary cycle, organic Rankine cycle, ORC, a

concentrating solar power, simulation, optimizationThe Stillwater Power Plant is the first hybrid plant in the world able to bring together a medium-enthalpy geothermal unit with solar

thermal and solar photovoltaic systems. Solar field and power plant models have been developed to predict the performance of the Still-water geothermal / solar-thermal hybrid power plant. The models have been validated using operational data from the Stillwater plant.

A preliminary effort to optimize performance of the Stillwater hybrid plant using optical characterization of the solar field has been completed. The Stillwater solar field optical characterization involved measurement of mirror reflectance, mirror slope error, and receiver position error. The measurements indicate that the solar field may generate 9% less energy than the design value if an appropri-ate tracking offset is not employed. A perfect tracking offset algorithm may be able to boost the solar field performance by about 15%.

The validated Stillwater hybrid plant models were used to evaluate hybrid plant operating strategies including turbine IGV posi-tion optimization, ACC fan speed and turbine IGV position optimization, turbine inlet entropy control using optimization of multiple process variables, and mixed working fluid substitution. The hybrid plant models predict that each of these operating strategies could increase net power generation relative to the baseline Stillwater hybrid plant operations.

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DOE-GTO Low Temperature Project Case StudyTom Williams1 and Greg Mines2 1National Renewable Energy Laboratory, Golden CO • 2Idaho National Laboratory, Idaho Falls ID

Keywords: Geothermal, binary, bottoming cycles, low-temperature power productionThe US Department of Energy (DOE), Geothermal Technologies Office (GTO) has funded low temperature projects to demonstrate

the technical and economic feasibility of power generation from geothermal resources at temperatures of 150°C and lower. To date three of the funded projects have completed their two year operation phase during which they supplied operating data to the GTO. This paper discusses the operation of two of these plants while they were providing data, including a review of facility performance, as well as an initial economic assessment of each.

Sarulla 330 MW Geothermal Project Key Success Factors in DevelopmentNir Wolf and Amnon Gabbay • nwolf@ormat.com • agabbay@ormat.com • Ormat, Reno, NV, USA

Keywords: Sarulla, geothermal power plant, Organic Rankine Cycle (ORC), Ormat Energy Convertor (OEC), binary, IndonesiaLocated in the Tapanuli Utara District, North Sumatra province in Indonesia, the 330 MW Sarulla power plant is set to be the world’s

largest geothermal power plant when its construction is completed in 2019. At this time construction has started but the story of the development of this power plant is a long and interesting one on many levels; it demonstrates the challenges and risks that geothermal developers will face on the road to success, from regulatory through economics, technical, legal and financing aspects. Many people and organizations have worked tirelessly for years to bring the plant to fruition and in this paper we shall outline the history and the various challenges the project has faced, highlighting the major criteria for overcoming such challenges, while ensuring successful development.

The project originally started development by Unocal in 1993, and in 2004 was retendered by PLN (the Indonesian national elec-tricity company). PLN took over Unocal’s interest in the JOC (Joint Operation Contract) and the PPA (Power Purchase Agreement). In 2006, the Medco-Ormat-Itochu Consortium won the tender to develop the project. Today the Consortium consists of Medco Energi Internasional Tbk, Ormat Technologies, Inc.; Itochu Corporation and Kyushu Electric Power Co. Inc.

Based on the above considerations, SOL (as contractor to PT Pertamina Geothermal Energy, “PGE”) formally gave notice of its intention to develop a geothermal power plant of approximately 330 MW capacity in the Sarulla Contract Area. This will be comprised of the following units (or stages) as set out in Appendix IV of the JOC.

• First Unit and Second Unit - the SIL Plant: approximately 83-110 MW in 2016 (possibly in several increments)• Third Unit and Fourth Unit - the NIL I Plant: approximately 76-110 MW in 2017 (possibly in several increments)• Fifth Unit and Sixth Unit - the NIL II Plant: approximately 76-110 MW in 2018 (possibly in several increments)

reGulatory

Assessment of Air Quality for Development Options at Olkaria Geothermal Field in KenyaCornelius J. Ndetei • Kenya Electricity Generating Company Ltd., Naivasha, Kenya • cndetei@kengen.co.ke

Keywords: Air quality assessment, geothermal emissions, CALMET/CALPUFF dispersion models, Olkaria Geothermal Project, hydrogen sulphide

Utilization of geothermal energy for direct and indirect uses is inexorably gaining momentum in many parts of the world endowed with the resource. Kenya has plentiful geothermal resources estimated to be over 10,000 MWe that have not been exploited to full potential. The power demand in Kenya exceeds the supply and has been growing at 8% per annum. Consequently, the Country has developed ambitious strategy, and intends to inject into the national grid an additional 5,000 MWe by the year 2017, which is about three times the existing capacity. Out of this, 700 MWe is expected to be generated from the Olkaria Geothermal Field.

Kenya Electricity Generating Company (KenGen), the leading power producer in Kenya, owns and operates 430MWe at the Olkaria I, II and IV power plants. In addition, KenGen has employed well head technology and is currently generating 46.1MWe from well head generators. Olkaria I & II Power Stations and some of the well head generators are located within Hell’s Gate National Park and are at close proximity to commercial flower farms and Lake Naivasha which is a Ramsar site. Geothermal operations emit hydrogen sulphide gas which may impact negatively on commercial flowers, vegetation and wild animals. Hence there is need to consider the cumulative effects of hydrogen sulphide gas emitted from the power plants. This paper assesses the potential air quality impacts associ-ated with the existing and proposed development options at Olkaria Geothermal Field. CALMET and CALPUFF dispersion models, which are recognised by US EPA, have been employed to assess the air quality associated with emissions from geothermal operations. Three different emission scenarios, representing the existing and the proposed geothermal development options have been considered.

Progress in Silencing ORC Turboexpanders in Geothermal ServiceThomas R. Norris, P.E., and Kier DeAnda • Consultants in Engineering Acoustics, Orinda, California USA

Keywords: Silencer, noise, ORC, Organic Rankin Cycle, turboexpander, ORC silencer, environmental noise, noise reduction, hearing protection, muffler

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Noise from the outlet pipe of large Organic Rankin Cycle (ORC) turboexpanders can impact acoustical permitting and employee job satisfaction at geothermal power plants. Specific acoustic concerns are environmental permit noise requirements, protection of hearing, and site-wide employee verbal communication ability. Until now, silencers for this service have often degraded within months to a year or two, or they have not provided as much noise reduction as desired. This paper describes progress on a new technology that successfully addresses both issues.

This paper is a progress report, documenting long-term silencing. The reported silencer is based on acoustic resonators, so there are no conventional acoustical materials, a potential problem area. This resonator technology has now been proven satisfactory over a four year period on four nominally 14 MW rated centrifugal Organic Rankin Cycle (ORC) turboexpanders. After four years of use, the silencers show no detected degradation of acoustical performance. Periodic inspections have found no damage, such as cracking due to acoustical fatigue.

The ORC working fluid is isobutane. One silencer was an insert type that could be pushed into an existing pipe. The other three silencers replaced a pipe section. Before silencing, noise levels can be 105-110 dBA at about three feet (about one meter) from the turbine outlet pipe. With the silencer, pipe noise was reduced approximately 20 dBA, and more near the blade passage frequency. Backpressure is judged satisfactory. Acoustic insulation of condenser inlet header piping was not required.

Alternative Water Policy Assessment for Enhanced Geothermal Systems — A Case StudyJenna N. Schroeder, Robert M. Horner, Christopher B. Harto, and Corrie E. Clark • Argonne National Laboratory

Keywords: Life cycle, alternative water, EGS, policy, CaliforniaThis paper is part of a larger analysis that examined alternative water policies for states with active EGS development (Harto et

al. 2014). The goal of that work was to better understand the regulatory structure that governs alternative waters in these areas and to assess the potential challenges that future EGS projects may face if they attempt to use such resources. Active development of EGS resources has historically occurred in areas that are water-scarce. Therefore, water availability has the potential to impact the long-term success of EGS development. California was chosen as the main focus of that analysis as it is the largest state in terms of installed geothermal capacity and has a complicated and unique regulatory structure for alternative waters. These waters represent an important but generally overlooked source that could be used by geothermal energy projects to replace the fluids lost during normal power plant operations. This paper shows that in general, regulatory frameworks for using recycled wastewater exist for geothermal projects. However, regulations for using other alternative water sources, such as produced water from oil and gas development, saline groundwater, and mine pool water, could not be found.

reservoir enGineerinG

3D Simulation of Mixed-Mode Poroelastic Fracture Propagation for Reservoir Stimulation Dharmendra Kumar and Ahmad GhassemiMewbourne School of Petroleum & Geological Engineering, The University of Oklahoma, Norman, OK, USA

Keywords: Poroelastic rock deformation, mechanical interaction, “stress shadowing” effect, multiple fracture propagation, mixed-mode fracture propagation

The paper presents three-dimensional numerical model for the multiple fracture propagation in the poroelastic reservoirs. The simulator model is developed based on the fully-coupled 3D poroelastic displacement discontinuity method for the hydro-mechanical response of the reservoir rocks and the linear elastic fracture mechanics for the fracture propagation. The reservoir rock mass is as-sumed homogenous and isotropic with constant poroelastic physical properties. The mixed-mode fracture propagation is analyzed using crack-tip opening displacement approach. Details of mathematical formulations and methodology for numerical implementation are presented first. Then, the numerical model is verified using analytical solution for a pressurized penny-shaped fracture. Finally, numerical examples for the fluid injection into a cluster of natural fractures and simultaneous propagation of pressurized multiple fractures in Westerly Granite are presented. The results demonstrate that along with the rock properties and the in-situ stress conditions, the “stress shadowing” effect which mainly depends on the spatial interval between the fractures plays a critical role in the multiple fracture propagation. Also, the simulation demonstrated that mixed-mode propagation can occur under influence of “stress shadowing”.

Modelling the Effects of Seasonal Variations in Rainfall and Production Upon the Aquifer and Surface Features of Rotorua Geothermal FieldThomas M. P. Ratouis, Michael J. O’Sullivan, and John P. O’Sullivan • t.ratouis@auckland.ac.nzDepartment of Engineering Science, The University of Auckland, Auckland, New Zealand

Keywords: Geothermal modelling, resource management, reservoir recovery, springs rejuvenation, seasonal variationThe Rotorua geothermal field is a shallow geothermal reservoir lying directly beneath the Rotorua city in New Zealand. It is renowned

for its abundance of natural geothermal manifestations including the geysers and hot springs at Whakarewarewa. Intensive extraction of the geothermal fluid in the 1970s led to a general decline of the activity of the surface features. In 1982 an extensive Monitoring Programme was initiated to provide insight into the system behaviour and response to geothermal production. Its conclusions led to the 1986 Wellbore Closure Programme that resulted in the recovery of reservoir pressures and many of the surface features. The monitoring programme continues through to the current day and efforts to provide a robust numerical model of the geothermal aquifer

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and surface features are ongoing. Annual and seasonal variations impacting the state of the field (e.g. production and reinjection rates, precipitation) have been included in University of Auckland (UOA) models: UOA Annual and UOA Seasonal. The results show the inclusion of these effects in the model is important for accurately representing the complexity of the Rotorua system and thus making the model useful for assisting with sustainable management of the resource.

Assessing the Effect of Realistic Reservoir Features on the Performance of Sedimentary Geothermal SystemsLuis E. Zerpa1, JaeKyoung Cho1, and Chad Augustine2 • 1Colorado School of Mines • 2National Renewable Energy Lab

Keywords: Sedimentary geothermal, numerical modeling, heterogeneity, reservoir modeling, natural fracture networkThe technical feasibility of commercial geothermal production from sedimentary reservoirs is being studied using numerical reservoir

modeling. This study considers sedimentary rock formations with relatively low permeability, with the purpose of expanding the current geothermal energy resources toward new regions. A numerical reservoir model, previously validated against an analytical model, is modified removing the analytical model assumptions to include more realistic behavior of fluids and reservoir rock. The performance of the sedimentary geothermal system is evaluated in terms of the hydraulic behavior (i.e., well productivity/injectivity), and thermal evolution of the reservoir (i.e., thermal breakthrough time). Here we present how changes of reservoir rock and water properties, as function of pressure and temperature, affect the performance of the sedimentary geothermal system. Particularly, water density and viscosity, and rock heat capacity play a significant role in geothermal reservoir performance. Also, the effects of heterogeneity and an-isotropy of rock properties are evaluated using reservoir simulation models with spatially-varying porosity and permeability. Premature thermal breakthrough is observed in cases where a high permeability streak is considered in the reservoir model. The dual permeability concept is applied to the reservoir model to study the performance of the sedimentary geothermal system considering networks of natural fractures. The parameters used to modify the behavior of the fracture network are the fracture conductivity and shape factor. The results show that a balance between hydraulic and thermal performance should be achieved to meet the target flow rate while also ensuring reservoir sustainability over the expected 30 year lifetime of the geothermal power plant. Therefore, sedimentary geothermal systems should be engineered to secure producing performance and operational sustainability simultaneously.

DNA-Encapsulated Silica Nanoparticle Tracers for Fracture CharacterizationYuran Zhang*, Timothy Spencer Manley*, Kewen Li, and Roland N. Horne • * Joint first authorsDepartment of Energy Resources Engineering, Stanford University, Stanford, CA, USAyuranz4@stanford.edu • tsmanley@stanford.edu • kewenli@stanford.edu • horne@stanford.edu

Keywords: Tracers, fracture characterization, DNA, silica, nanoparticlesThe objective of our experiments has been to develop and evaluate a uniquely identifiable particle tracer for use in geothermal ap-

plications. Following the work of Paunescu et al. (2013), DNA-tagged nanotracers have been made by adsorbing synthetic DNA onto silica nanoparticles which were then coated with silica to protect the DNA. The silica nanoparticles were then evaluated for durability with a controlled heat experiment at 198°C and flowed through packed sand at 25°C, 120°C, and 150°C while monitoring permeability changes. All were subsequently analyzed with SEM imaging.

resourCe assessment

Geothermal Prospector: Supporting Geothermal Analysis Through Spatial Data Visualization and Querying ToolsDaniel Getman1, Arlene Anderson2, and Chad Augustine1

1National Renewable Energy Laboratory • 2U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy

Keywords: Data, visualization, GIS, spatial, DOE, database, NGDS, geothermal, ProspectorDetermining opportunities for geothermal energy can involve a significant investment in data collection and analysis. Analysts

within a variety of industry and research domains collect and use these data; however, determining the existence and availability of data needed for a specific analysis activity can be challenging and represents one of the initial barriers to geothermal development [2]. This paper describes the motivating factors involved in designing and building the Geothermal Prospector application, how it can be used to reduce risks and costs related to geothermal exploration, and where it fits within the larger collection of tools that is the National Geothermal Data System (NGDS) [5].

Using Geothermal Play Types as an Analogue for Estimating Potential Resource SizeRachel Terry1,2 and Katherine Young2 1University of Tennessee at Chattanooga • 2National Renewable Energy Laboratory, Golden CO, USA

Keywords:

Geothermal occurrence models, play types, geothermal, risk, resource potential, geology, exploration, resource size, temperature, volume, Monte Carlo, heat in place, USGS, resource assessment, probability distribution, recoverable heat, electric potential, OpenEI, reservoir characteristics, parameters

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Blind geothermal systems are becoming increasingly common as more geothermal fields are developed. Geothermal development is known to have high risk in the early stages of a project development because reservoir characteristics are relatively unknown until wells are drilled. . Play types (or occurrence models) categorize potential geothermal fields into groups based on geologic character-istics. To aid in lowering exploration risk, these groups’ reservoir characteristics can be used as analogues in new site exploration. The play type schemes used in this paper were Moeck and Beardsmore play types (Moeck et al. 2014) and Brophy occurrence models (Brophy et al. 2011). Operating geothermal fields throughout the world were classified based on their associated play type, and then reservoir characteristics data were catalogued. The distributions of these characteristics were plotted in histograms to develop prob-ability density functions for each individual characteristic. The probability density functions can be used as input analogues in Monte Carlo estimations of resource potential for similar play types in early exploration phases. A spreadsheet model was created to estimate resource potential in undeveloped fields. The user can choose to input their own values for each reservoir characteristic or choose to use the probability distribution functions provided from the selected play type. This paper also addresses the United States Geological Survey’s 1978 and 2008 assessment of geothermal resources by comparing their estimated values to reported values from post-site development. Information from the collected data was used in the comparison for thirty developed sites in the United States. No sig-nificant trends or suggestions for methodologies could be made by the comparison.

Geothermal Resource Reporting Metric (GRRM) Developed for the U.S. Department of Energy’s Geothermal Technologies OfficeKatherine R. Young1, Anna M. Wall1, and Patrick F. Dobson2 • katherine.young@nrel.gov1National Renewable Energy Laboratory (NREL), Golden CO • 2Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA

Keywords: Reporting metric, reporting code, resource assessment, geothermal grade, polar area chartThis paper reviews a methodology being developed for reporting geothermal resources and project progress. The goal is to provide

the U.S. Department of Energy’s (DOE) Geothermal Technologies Office (GTO) with a consistent and comprehensible means of evaluat-ing the impacts of its funding programs. This framework will allow the GTO to assess the effectiveness of research, development, and deployment (RD&D) funding, prioritize funding requests, and demonstrate the value of RD&D programs to the U.S. Congress and the public. Standards and reporting codes used in other countries and energy sectors provide guidance to develop the relevant geothermal methodology, but industry feedback and our analysis suggest that the existing models have drawbacks that should be addressed. In order to formulate a comprehensive metric for use by the GTO, we analyzed existing resource assessments and reporting methodolo-gies for the geothermal, mining, and oil and gas industries, and sought input from industry, investors, academia, national labs, and other government agencies. Using this background research as a guide, we describe a methodology for evaluating and reporting on GTO funding according to resource grade (geological, technical and socio-economic) and project progress. This methodology would allow GTO to target funding, measure impact by monitoring the progression of projects, or assess geological potential of targeted areas for development.

resourCe manaGement

Monitoring Ground-Surface Heating During Expansion of the Casa Diablo Production Well Field at Mammoth Lakes, CaliforniaDeborah Bergfeld1, R. Greg Vaughan2, William C. Evans1, and Eric Olsen3 1U.S. Geological Survey, Menlo Park, CA • 2U.S. Geological Survey, Astrogeology Science Center, Flagstaff, AZ3Aerial Thermal Imaging, Salt Lake City, UT

Keywords: Thermal Infrared (TIR) imagery, diffuse CO2 degassing, ground heating, Long Valley caldera, geothermal monitoringThe Long Valley hydrothermal system supports geothermal power production from 3 binary plants (Casa Diablo) near the town

of Mammoth Lakes, California. Development and growth of thermal ground at sites west of Casa Diablo have created concerns over planned expansion of a new well field and the associated increases in geothermal fluid production. To ensure that all areas of ground heating are identified prior to new geothermal development, we obtained high-resolution aerial thermal infrared imagery across the region. The imagery covers the existing and proposed well fields and part of the town of Mammoth Lakes.

Imagery results from a predawn flight on Oct. 9, 2014 readily identified the Shady Rest thermal area (SRST), one of two large areas of ground heating west of Casa Diablo, as well as other known thermal areas smaller in size. Maximum surface temperatures at 3 thermal areas were 26–28 °C. Numerous small areas with ground temperatures >16 °C were also identified and slated for field investigations in summer 2015. Some thermal anomalies in the town of Mammoth Lakes clearly reflect human activity.

Previously established projects to monitor impacts from geothermal power production include yearly surveys of soil temperatures and diffuse CO2 emissions at SRST, and less regular surveys to collect samples from fumaroles and gas vents across the region. Soil temperatures at 20 cm depth at SRST are well correlated with diffuse CO2 flux, and both parameters show little variation during the 2011–14 field surveys. Maximum temperatures were between 55–67 °C and associated CO2 discharge was around 12–18 tonnes per day. The carbon isotope composition of CO2 is fairly uniform across the area ranging between –3.7 to –4.4 ‰. The gas composition of the Shady Rest fumarole however has varied with time, and H2S concentrations in the gas have been increasing since 2009.

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sCalinG & mineral extraCtion

Assessment of CHIM-XPT and Watch in Predicting the Calcite Scaling Potential of Geothermal WellsV. C. Clemente1 , K. S. Faja1, M. H. Reed2, L. M. Daco-ag1, and R. J. T. Tamboboy1

1Energy Development Corporation, Pasig City, Philippines • 2University of Oregon, Eugene, OR, USA

Keywords: Geothermal, wells, calcite scaling, software, Philippines Calcite scaling is one of the problems besetting geothermal energy production. Early detection of the calcite scaling potential of

geothermal wells will be helpful in assessing the project economics due to intervention measures that have to be adopted to mitigate calcite scaling or clear calcite scales from geothermal wells, since these will result in additional production costs, as well as formulat-ing the appropriate production well monitoring strategy. Early detection of the calcite scaling tendency of a well can be modeled using geochemical software. This paper assesses the software watch and solveq/chim-xpt, two widely used programs by the geothermal industry, in predicting the calcite scaling potential of wells.

Screening the Effects of Ligand Chemistry and Geometry on Rare Earth Element Partitioning From Saline Solutions to Functionalized AdsorbentsClinton W. Noack1, Kedar Perkins2, Newell Washburn2, David A. Dzombak1, and Athanasios K. Karamalidis1 1Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA, USA2Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA

Keywords: Resource recovery, solid phase extraction, functionalized adsorbentsThe goal of the project is to prepare adsorbents, solid supports functionalized with organic ligands, for separation and recovery

of lanthanides from chemically complex geothermal fluids of geothermal power plants. The project involves initial development and testing of low-cost, reusable functionalized adsorbents for selective recovery of critical elements from geothermal fluids in multistep processes, with pre-concentration of rare earth elements (REE) on the resin and recovery by acid elution. Ligands with known abil-ity to bond selectively with REE in aqueous solution are examined. Tests with simulated low-temperature geothermal waters under simulated extraction process conditions are conducted. Results of material characterization and uptake experiments are presented.

Modular Solid-State Thermoelectric Power Generation and High-Value Lithium Recovery From Low-Temperature Geothermal BrinesJacob Rajterowski1, Jay E. Renew, P.E.2, and Ryan Melsert3 • jrenew@southernresearch.org1Southern Research, Water Research Center, Cartersville, GA • 2Southern Research, Water Research Center, Cartersville, GA 3Southern Research, Advanced Energy and Transportation Technologies, Durham, North Carolina

Keywords: Geothermal, low temperature, modular, thermoelectric generator, membrane distillation, manganese oxide, lithium extraction, silica removal, and nanofiltration

Southern Research and its partners are developing an innovative modular solid-state thermoelectric based system designed to both generate electricity and extract high-value minerals from low-temperature geothermal brines. This system treats incoming low-temperature brine, uses a novel membrane separation process to extract water vapor from the brine, and utilizes this condensing vapor to provide a heat load to a thermoelectric generator. As water vapor is removed, the brine is concentrated, facilitating downstream extraction of high-value minerals, such as lithium, through a manganese oxide based extraction process.

The system provides both large quantities of previously inaccessible base-load renewable electricity to the grid, and high-value lithium to the critical minerals market. As all components in this system are highly modular, it can be deployed at a variety of scales dependent on quantity of thermal and mineral resources.

Case Study of the Change of Scale With ProductionNorio Yanagisawa • n-yanagisawa@aist.go.jpInstitute for Geo-Resources and Environment, Higashi, Tsukuba, Ibaraki, Japan

Keywords: Scale, silica, metal sulfide, pH, KakkondaIn geothermal field, the fluid geochemistry of several production well changed with operation of geothermal power plant. The

change of fluid geochemistry affects to scale properties. For example, the Kakkonda geothermal field, North-eastern Japan, several deep reservoir is developed until the boundary between

Quaternary Kakkonda granite and Pre-Tertiary formations. On progress of production the fluids from deep reservoir suffered by the fluid of shallow reservoir and meteoritic water. With

temperature of production well decreasing and chemical composition changed, silica precipitation decreased and the metal sulfide mineral assemblage of scales of Well-13 changed from chalcocite (Cu2S), loellingite (FeAs2) and native antimony (Sb) to tetrahedrite (Cu10[Fe,Zn]2[As,Sb]4S3).

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sedimentary basin

Geostatistical Analysis of Bottom-Hole Temperatures in the Denver and Williston Basins: North AmericaAnna Crowell • Harold Hamm School of Geology and Geological Engineering, University of North Dakota

Keywords: Geostatistics, GIS, Williston Basin, Denver Basin, Bottom-Hole TemperaturesBottom-hole temperatures (BHTs) obtained from oil and gas wells have never been completely reliable due to the formation

temperature disturbance caused by the influence of the drilling mud on the formation rock during drilling. A correction method must be applied before any BHT data can be used. The source and method of the correction, however, has been a topic of dissention since the early 70s, when BHTs began to be used for estimates of temperature at depth to determine such things as hydrocarbon maturity, thermal history, and geothermal energy assessment.

Several correction methods are currently used: the Harrison (Harrison et.al., 1983), Kehle (Kehle et.al., 1970), and Förster (Förster et.al., 1996) are among the most prevalent. None of these methods yield a correction that represents a statistically accurate distribution of BHTs, although the Harrison and Kehle have been found to be a much better approximation (Crowell and Gosnold, 2013). All of these methods were developed using a top-down approach, where an equilibrium temperature profile has been obtained and a correc-tion equation was developed to attempt to shift the best fit line of the data points to the best fit line of the data obtained at equilibrium.

In addition, formation data are not always included with the bottom-hole temperature data. This makes resource assessment based on formation difficult, if not impossible. We therefore hypothesize that by using two geostatistical methods, Moran’s I and Getis-Ord, we will be able to evaluate if a better correlation exists between a depth-interval well parsing versus a geochronological unit well parsing, and if a correlation exists, is it strong enough to indicate that a correction factor is possible.

Discrete Fracture Network Simulation for Sedimentary Enhanced Geothermal Systems: Red River Formation, Williston Basin, North DakotaCaitlin M. Hartig • University of North Dakota

Keywords: Sedimentary enhanced geothermal systems (SEGS), discrete fracture network (DFN), North American stress regime, surface lineaments, subsurface faults, ArcGIS, geostatistical analysis

The Red River Formation (Ordovician), which lies between 3.6 and 4.2 km depth in the Williston Basin, is a viable site for installa-tion of sedimentary EGS (SEGS). SEGS is possible there because temperatures in the formation surpass 140° C and the permeability is 0.1-38 mD; fracture stimulation can be utilized to improve performance. A GIS and geostatistical analysis was completed to show that there is a satisfactory correlative relationship between the surface lineaments and the basement faults in the study area. Consequently, the orientations and locations of the surface lineaments and basement faults were combined in a shapefile to represent the area’s discrete fracture network. In the future, the results of these two analyses can be utilized to create a reservoir simulation model of an SEGS in the Red River Formation; the purpose of this model would be to ascertain the thermal response of the reservoir to fracture stimulation.

Sedimentary Basin Geothermal Resources in the Piceance Basin, ColoradoPaul Morgan • Colorado Geological Survey, Colorado School of Mines, Golden CO, USA

Keywords: Sedimentary basin, geothermal resource, Piceance Basin, Colorado, Leadville Limestone, bottom-hole temperature, temperature log, Geotherm

The Piceance Basin is a major oil and gas producing basin in western Colorado. More than 27,000 bottom-hole temperatures (BHTs) from oil and gas wells in the basin have been corrected for the drilling disturbance. When these data were plotted as a func-tion of the well depth the plots indicated changes in the geothermal gradient that roughly correlated with changes in lithology and thermal conductivity. The BHTs were separated into groups based on the stratigraphic intervals in which their wells were completed and geothermal gradient maps prepared for each group. The geothermal gradient maps also indicate a change in gradient as the strati-graphic intervals increased in depth and also showed a general increase in gradient to the south of the basin. Commercial temperature logs were digitized from some of the wells in the basin, including one very deep well. The temperature logs indicated temperature in general agreement with the BHT data except the log from the very deep well. The very deep well had two very different gradients which were interpreted to result from a long-term water flow at a steady temperature in the Dakota Formation about two-thirds down the well. The most suitable formation for a geothermal reservoir is probably the Mississippian Leadville Limestone which has intrinsic porosity, fracture, and karst permeability.

tools

Cementing Tool Supports Cement Plug in Large Diameter Geothermal Well CasingOzgur Balamir1, Wm. M. Rickard1, Fred Wilson1, Kristian Harestad2, and Per Arild Årebråt2 1Geothermal Resource Group, Inc., Palm Desert, CA • 2Perigon AS, Randaberg, Norway

Keywords: Cement plug, cement support tool, coiled tubing, workover, drilling cost, Hudson Ranch, Salton SeaCement plug setting is one of the most unpredictable and time consuming operations in the drilling process of a geothermal well,

thus adding considerable cost and risk to drilling, completion, and workover operations. Setting of ten to twenty consecutive plugs for

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a single sidetracking job, each requiring up to 8 hours of wait time for the cement to cure, are not unheard of in the industry. Significant risk arises from the inability to support the cement slurry while it cures inside the wellbore.

Perigon’s cement support tool (CST™) was designed to increase the success rate of setting cement plugs by physically separat-ing the plug from the drilling fluid while the slurry cures, just as if it was set at the bottom of a well or above a bridge plug. Another attractive feature of the CST™ tool is its drillability, and foldable aluminum and composite construction (Harestad, 2015), which enables it to be pumped through small diameter tubing and then enlarged in the well bore. This paper summarizes a recent, first-ever and successful plug setting operation using coiled tubing in a large diameter geothermal well casing.

Ultra-High Temperature (250°C+) and Wide Operating Temperature Range Ultracapacitor Enabling Downhole Power Source for Geothermal ExplorationNicolo Brambilla and Fabrizio Martini • FastCAP Systems, Boston MA • www.fastcapsystems.com

Keywords: 250°C Ultracapacitor, ultra-high temperature energy storage, wide temperature range ultracapacitor, geothermal exploration, downhole energy storage, extreme environment ultracapacitor, nanotechnology, lithium-free energy storage, sub-zero ultracapacitor, low temperature ultracapacitor

FastCAP developed a novel and innovative ultra-high temperature ultracapacitor (“ultracap”) energy storage device showing out-standing performance suitable for geothermal exploration applications. This proposed ultracap is an upgraded version of the previous 200°C presented at GRC Summit 2014. The ultracap performs reliably at ultra-high operating temperatures of 250°C and beyond and operates over an extremely wide operating temperature range, -5°C to 250°C+. The rechargeable ultracap has significantly higher power density than lithium thionyl chloride batteries, a non-rechargeable incumbent used in oil and gas drilling today. Several her-metically sealed, commercial ready prototype devices were tested in our laboratories at constant temperatures of 250°C+ showing no significant degradation over 1000 hours of operation (See Figure 1). Six similar prototypes will be tested at Sandia National Lab in the month of April, 2015 for an overall performance third party validation. We expect these devices to show very good performance over 1000 hours of operation at three rated temperatures, 200°C, 225°C and 250°C+, with negligible capacitance retention and minimal equivalent series resistance (ESR) increase. Deployment of these novel ultra-high temperature ultracapacitors in geothermal drilling and exploration applications could have an immediate and significant impact on the effectiveness and efficiency of drilling processes, particularly with regard to use of advanced logging and monitoring techniques in the geothermal context.

Development of a Digital Output Temperature Probe for Precision MeasurementsKamil Erkan1, Murat Doğruel1, Kemal Bayat1, Bülent Akkoyunlu1, Mete Tayanç1, Elif Balkan2, and Savas Hamamcı1 1Faculty of Engineering, Marmara University, Istanbul, Turkey2Faculty of Engineering, Dokuz Eylul Univeristy, Izmir, Turkey

Keywords: Geophysics, exploration, tool development, well logging, temperature logging Electrical wireline methods are generally used for precision temperature-depth measurements. In general, four-wire transmission

cables are used for eliminating the cable resistance effects. These systems are vulnerable due to the requirements of keeping the cable integrity against breakdown of the electrical insulation. A digital output temperature probe allows using a mono-wire data transmission cable thus increasing the cable integrity. We report the design and the early test results of a digital output temperature probe.

Integrated Cooling Systems for an Extended Operation Range of Borehole ToolsBenedict Holbein1, Jörg Isele2, and Luigi Spatafora3

1M.Sc., Responsible for Cooling System Development • 2Dr. Eng., Team Leader Geothermal Group at IAI: ZWERG Project3M.Sc., Material Expert of ZWERG Project, Institute for Applied Computer Science IAI, Karlsruhe Institute of Technology KIT, Eggenstein-Leopoldshafen, Germany

Keywords: Deep geothermal energy, cooling systems, heat management, investigation & exploration, geothermal researchFor investigation and interaction operations in deep boreholes the problem of overheating of electronics and sensors is imminent.

One of the central engineering topics of the workgroup for the development of borehole tools at the Institute for Applied Computer Science is therefore the evaluation of different cooling methods. The first tool, based on the system platform for borehole tools ZWERG, the video inspection system GeoKam is cooled by an integrated PCM (Phase Change Material) cooling system, which is suitable for operation periods of up to 8 hours at a surrounding temperature of 165 °C. Besides this temporary cooling method a borehole cool-ing machine for continuous cooling is part of the current development effort. However basic engineering topics i.e. solutions for heat insulation, pressure and corrosion resistant housings and seals are regarded as well.

A New Technique and Sensor for Determining Steam Quality Along a WellboreRobert Kerr, Brian D. Gleason, Adam Olzick, and Bill Denzel • Scientific Drilling International

Keywords: High temperature, steam quality, density, densitometer, pressure, geothermal technique, tuning fork, high temperature transducer, cased hole services, steam injection, steam, prototype, high sensitivity, high resolution, steam quality sensor

Current downhole steam quality measurement techniques involve post processing of production logs. These logs are created by recording sensor measurement samples at points along the wellbore including temperature, pressure, and mass or volumetric flow rates using a spinner-type flowmeter. Since steam expands when travelling up a wellbore due to decreasing hydrostatic pressure, the

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quantification of inflow steam parameters utilizing this technique can be difficult to interpret. This paper presents a new technique for measuring steam quality along a wellbore that utilizes a new high temperature densitometer sensor combined with corresponding temperature or pressure readings. The technique has the benefit of providing a direct measurement of steam quality, thereby eliminat-ing post processing of the production logs and reducing errors during the interpretation. To better understand the benefits of this new densitometer-based approach, this paper discusses existing approaches and presents several alternate techniques that were researched early on in the project. This paper also discusses the theory of the new measurement technique, as well as some preliminary accuracy estimations, their empirical verification, and materials research that was required to develop the new sensor.

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AlphAbeticAl index of Authors

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AAdam, Ludmila 22Admassu, Engdawork 9Agahi, Reza 31Akkoyunlu, Bülent 41Al-Amri, Abdullah 17Allis, Rick 1, 2, 15, 22Anderson, Arlene 37Anderson, Brian 28Angelini, Lorenzo 34Årebråt, Per Arild 40Astanah, Nayyereh Mirnabavi 19Athens, Noah 29Atwa, Victor 7Augustine, Chad 14, 37Aureli, Matteo 33Austin, Andrew 8Avery, John 31

B

Bachmann, Corinne 23Bahrami, Davood 14Baker, Reed 14Baker, Walt 7Balamir, Ozgur 40Balkan, Elif 41Barasa, Philip J. 9Batchelor, Chase 31Bayat, Kemal 41Beitler, Carrie 31Bellani, Stefano 16Bell, Jason 7Bell, John W. 21Bell, Sean 7Benediktsson, Davíð Örn 6Benn, Brian 31Bennett, Carlon R. 29Benoit, Dick 1Bergfeld, Deborah 38Bertani, Ruggero 3Bielicki, Jeffrey 29Bierre, Emily 32Bizzarri, Fabrizio 34Blake, Kelly 14, 16Blankenship, Douglas 12, 14Bolat, Rahmi 28Bolton, Dan 7Bonafin, Joseph 32Bowman, John R. 20Boyd, O. Sierra 11Boyd, Tonya L. 3Bradford, Jacob 11Brady, Mark 28Brambilla, Nicolo 41Brikowski, Tom 2Brown, Donald 13Burns, Erick 29

alphabetiCal index of authors

CCallahan, Owen A. 19Calvin, Wendy 12, 14Camp, Erin 28Camp, Victor 17Canchola-Félix, Ismael 32Candela, Dr. Philip 18Cannon, Cody 18Cantwell, Carolyn 28Chandrasekharam, D. 18Chandrasekhar, V. 18Cho, JaeKyoung 37Cladouhos, Trenton T. 11, 19, 27Clark, Corrie E. 36Clemente, V. C. 39Cohan, Sander 34Cole, Ryan A. 27Conrad, Mark E. 18, 28Consoli, Daniele 34Coolbaugh, Mark F. 26, 27, 30Crewson, Justin 3Crowell, Anna 25, 40Crowell, James “Josh” 22Cui, Mingjie 24Cumming, William 26, 27, 30Curie, Marie 33Czajkowski, Jessica L. 27

D

Daco-ag, L. M. 39Dai, Chuanshan 24Danko, George 14Davatzes, Nicholas 27DeAnda, Kier 35DeAngelo, Jacob 4, 29Dell, Robert 4, 5De Marzo, Alessio 34Denninger, Kate 7Denzel, Bill 41DeOreo, Steve 14dePolo, Craig M. 26Dershowitz, William 12DiPippo, Ronald 32di Schio, Clotilde Rossi 32Dobson, Patrick F. 18, 28, 29, 38Doe, Thomas 12Dogruel, Murat 41Doumanidis, Haris 33Drakos, Peter 12Dreger, Douglas S. 11Durán, Evert 22Duvia, Andrea 32Dzombak, David A. 39

E

Echt, William 33

Einarsson, Gunnlaugur M. 20Eker, Erdinc 14Erkan, Kamil 41Etzel, Thomas M. 20Eustes, Alfred 7, 14Evans, James P. 29Evans, William C. 38

F

Fairley, Jerry 16, 17Faja, K. S. 39Farabi Asl, Hadi 5Farmahini-Farahani, Moien 11Fatahillah, Hilmi El Hafidz 24Faulds, James E. 12, 14, 17, 22, 26Ferguson, Colin 28Finnila, Aleta 12Fisher, Meghan 2Fleckenstein, William 14Foley, Paul 17Foley, William 4, 5Forson, Corina 27Fowler, Andrew 28Frazer, Neil 28Frone, Zachary 28Fu, Wencheng 33Fujii, Hikari 5Fullerton, Rob 32

G

Gabbay, Amnon 35García-Gutiérrez, Alfonso 32, 34Garg, Sabodh 29Gasperikova, Erika 28, 29Gehringer, Magnus 5Getman, Daniel 37Ghassemi, Ahmad 11, 36Gherardi, Fabrizio 16Gilliland, John 8Glassley, William 28Gleason, Brian D. 41Glen, Jonathan M. 12, 14, 29Golla, Glenn 20Gosnold, William D. 24, 25Gritto, Roland 11Gutiérrez-Negrín, Luis C.A. 27Gwynn, Mark L. 1, 15, 25

H

Hamamcı, Savas 41Hammond, William C. 26Harðarson, Björn S. 10, 20Hardwick, Christian L. 15, 22, 25, 31Harestad, Kristian 40Harp, Dylan 29

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Harris, David 17Hartig, Caitlin M. 40Hartline, Craig S. 23Harto, Christopher B. 36Harvey, William 34Hawkes, Samuel 28He, Xiaoning 28Heidbach, Oliver 23Hickman, Stephen 12, 14Hinz, Nicholas H. 12, 14, 17, 26, 27,

28, 30Holbein, Benedict 41Hornbach, Matthew 28Horne, Roland N. 13, 37Horner, Robert M. 36Horowitz, Frank 28House, Leigh 13Huang, Daxing 33Huang, Wei-Chuang 16Hutchings, Lawrence 23

I

Inanli, Mustafa 33Intani, Rindu Grahabhakti 20Isele, Jörg 41Ishido, Tsuneo 24Ito, Garrett 28Itoi, Ryuichi 6

J

Jacobo-Galván, Paul V. 32Jacobs, Amelia 7Jalilinasrabady, Saeid 6Jiulong, Liu 6Jóhannesson, Thirleikur 6Johnson, Stu 15Jones, Clay G. 20Jónsson, Magnús Þór 8Jordan, Teresa 28

K

Kahutu, James 7Karamalidis, Athanasios K. 39Karanja, Nahashon 7Karlsdóttir, Ragna 20Karra, Satish 29Kaven, Ole 14Kelkar, Sharad 13Kelley, Richard 29Kelley, Shari 29Kennedy, B. Mack 12, 14, 30Kerr, Robert 41Ketcham, Richard A. 19Khaemba, Abraham W. 8Kikuchi, Takuma 13Kirby, Stefan 1, 2Kitz, Kevin 32Kolar, Mark 33

Kosukegawa, Hiroyuki 5Kreemer, Corné 26, 30Kristinsson, Sigurdur G. 20Kumar, Dharmendra 36

L

Laboso, Roselyne 23Larson, Benjamin 19Larson, Peter 16, 17Lautze, Nicole 28Lazaro, Michael 14, 16Lei, Haiyan 24Li, Kewen 13, 37Libbey, R. B. 18Liberty, Lee M. 29Lindsey, Cary 16, 17Lindsey, Nate 23Lubenow, Brady 17Lund, John W. 3Lv, Junxin 6Lynne, Bridget Y. 20

M

Magro, Gabriella 16Mamrosh, Darryl 31Manley, Timothy Spencer 37Mann, Michael 25Maris, Virginie 30, 31Martinez, Daniella 13Martínez-Estrella, Juan I. 32, 34Martini, Fabrizio 41Mathenge, Rose W. 9Mattson, Earl D. 18McClain, J. S. 28McConville, Emma Grace 18McCullough, Jess 14McCurry, Michael 2McDonald, Mark R. 24McIntush, Kenneth E. 31McLaren, Robert 12McLennan, John 11McLing, Travis L. 18McMillan, Nicholas 16Meade, Dave 16Meigs, Andrew J. 30Mellors, Robert J. 17Melosh, Glenn 26, 27, 30Melsert, Ryan 39Miah, Mamun 23Middleton, Richard 29Mikada, Hitoshi 18Mines, Gregory L. 15, 25, 34, 35Mink, Leland 17Miyora, Thomas 8Mizushima, Akihiro 18Mohr, Felix 31Molisee, Danielle D. 21Moore, Joseph N. 1, 2, 11, 15, 18, 20,

30, 31

Morgan, Paul 40Moulding, Ann 2Mwania, Michael M. 21

N

Nagandran, Uneshddarann 7Nash, Gregory D. 20, 29, 31Natwotniak, Shannon K. 2Nawa, Kazunari 24Ndetei, Cornelius J. 35Neupane, Ghanashyam 18Nielson, Dennis 29Nishi, Yuji 24Noack, Clinton W. 39Nordeng, Stephan H. 24, 25Nordin, Yini 11Nordquist, Josh 12Norman, David K. 27Norris, Thomas R. 35Numakura, Tatsuya 13

O

Olsen, Eric 38Olson, Jeffrey 14Olzick, Adam 41Oppliger, Gary 26Orme, Christopher J. 25Ortiz-Bolaños, Ángel A. 34Osgood, Steve 33O’Sullivan, John P. 36O’Sullivan, Michael J. 36Ovando-Castelar, Rosember 32

P

Pan, Baozhi 13Pankow, Kristine L. 31Parlaktuna, Mahmut 6Patsa, Eleni 6Pearson, David M. 2Pepin, Jeff D. 29Perkins, Kedar 39Person, Mark 29Petty, Susan 11Phelps, Geoff 14Piccoli, Philip 18Podgorney, Robert 11Porkhial, Soheil 19Pyatina, Tatiana 8

Q

Queen, John H. 26Quick, Ralph 7

R

Rahayu, Dewi Maria 24Rajterowski, Jacob 39

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R

Ratouis, Thomas M.P. 36Reede, Chris 33Reed, Marshall J. 4Reed, M. H. 39Renew, Jay E. 39Richards, Maria 28Rickard, Wm. M. 40Rivas-Cruz, Fernando 34Robertson-Tait, Ann 12, 14Ronoh, Irene 10Ruiz, D. A. Rocha 21

S

Sabin, Andrew 12, 14, 16Sadowski, Andrew J. 22Sakaguchi, Kiyotoshi 13Savy, Jean 23Schiffman, Peter 28Schmalzle, Gina M. 27Schroeder, Jenna N. 36Schuchmann, Hannah 28Shervais, John W. 29Shevenell, Lisa A. 26, 27, 30Shurtleff, Paul 34Sifford, Alex 3Siler, Drew L. 12, 14, 17, 26, 28, 29Simmons, Stuart D. 1, 2, 31Singh, Ankit 23Singh, H. K. 18Skeehan, Kirsten 17Smith, Jared 28Smith, Jerry 17Soma, Nobukazu 24Sonnenthal, Eric L. 29, 30Spatafora, Luigi 41Spycher, Nicolas 28Stedinger, Jery 28Stelling, Pete 26, 27, 30Sugama, Toshifumi 8Sugihara, Mituhiko 24Sutula, Glenn 29Swyer, Michael W. 11, 27

T

Takekawa, Junichi 18Tamboboy, R. J. T. 39Tayanç, Mete 41Terry, Rachel 37Tester, Jefferson 28Thomas, Donald 28Thompson, Alison 3Tiedeman, Andrew 16Tilley, Mitch 7Tiwari, Shashank 11Trimble, John D. 30Trupti, G. 18Tsuchiya, Noriyoshi 13Turchi, Craig S. 34Tutti, Faramarz 19

Þ

Þórhallsson, Sverrir 8

U

Uddenberg, Matthew E. 11Ulrich, Craig 28Unnthorsson, Runar 4, 5Uwera, Jane 6

V

Valdimarsson, Pal 33van Wijk, Kasper 22Van Zyl, Dirk 6Vaughan, R. Greg 38Vazquez-Rubio, Ivan G. 14Visser, Charles F. 7, 26, 29

W

Wall, Anna M. 38Waller, David 28Wallis, Irene 22Walters, Mark A. 23

Wamalwa, Ruth 10, 19Wang, Zhigang 33Wannamaker, Philip E. 2, 22, 26, 30,

31Washburn, Newell 39Watanabe, Noriaki 13Wei, C. S. 4, 5Wei, Zhang 6Welcker, Kelydra 28Welhan, John 2, 15Wendt, Daniel S. 25, 34Whealton, Calvin 28Williams, Colin F. 4, 12, 14Williams-Jones, A. E. 18Williams, Tom 35Willis, Hobie W. 25Wilmarth, Maxwell 26Wilson, Aaron D. 25Wilson, Daniel Robert 8Wilson, Fred 40Witcher, James 29Wolf, Nir 35Wood, Thomas R. 18Worku, Selamawit 9Worthing, Wade 18Wright, Melinda C. 23

Y

Yanagisawa, Norio 39Young, Katherine R. 37, 38

Z

Zarei, Elahe 19Zarrouk, Sadiq J. 6Zerpa, Luis E. 37Zhang, Yingqi 28Zhang, Yuran 37Zhu, Guangdong 34Zierenberg, Robert 28Zúñiga, R. Hernández 21