a study of a risper kandie generic engineered …thirty-fourth workshop on geothermal reservoir...

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A STUDY OF A GENERIC ENGINEERED GEOTHERMAL SYSTEM (EGS)/HOT DRY ROCK

Risper KandieGeologistKenGen

Kenya

ion

Summary� Overview � Concept � Status of current projects� Geographical distribution� Limitations� Reservoir simulation� Results� Conclusion

EAPIC 2011, Kampala, Uganda www.eapicforum.com

Overview of EGS�Not site specific

�No natural convective hydrothermal resources�Enhancement of permeability and porosity

�Fracturing of hot dry rock through hydraulic fracturing

�Concept developed to fulfill energy demands�Has great potentials though with limitations


Concepts of EGS/HDR�Underground thermal energy

�Recover by ‘engineering’ the formation�Drill a well configuration into high T0C rock

�Doublet�Triplet

�Quadruplet�Cold Water injected at high pressure�Hot fluids to the surface through production well


Status of Current EGS Projects �Soultz- sous Foret in France

�Located in the Upper Rhine Graben�The plant began to produce 1.5 MWe in 2008

�3 wells drilled in the granite rock to 5 Km�Other HDR/EGS projects

�Australia, Japan, Germany, U.S.A, SwitzerlandEAPIC 2011, Kampala, Uganda www.eapicforum.com

Project Type Country Size[MWe]

Plant Type Depth[Km]

Status

Soultz R&D France 1.5 Binary 4.2 Operational

Desert Peak R&D U.S 11-50 Binary Development

Landau Commercial Germany 3 Binary 3.3 Operational

Paralana Commercial Australia 7-30 Binary Drilling

Cooper basin

Commercial Australia 250-500 Kalina 4.3 Drilling

Geyser R&D U.S - Flash 3.5-3.8 Drilling

Basel R&D Switzerland 3 Binary 5 Suspended


Status of Current EGS Projects

Limitations�Requires large quantities of water

�Induced seismicity

�Potential aquifer contamination

�Maintenance cost affected by scaling,

corrosion and mineral deposition

�Drilling costs


Reservoir Simulation�EGS aims at extracting thermal energy from hot

impermeable rocks

�This is achievable with the use of hydraulic fracturing technique

�The technique stimulates thermal reservoir �It creates permeability network with fluid –rock

surface area large enough for thermal energy extraction


Numerical Reservoir Model Simulator�Done with TOUGH-2

�Developed at LBNL of US Dept of Energy(DOE)�Creation of 3 data files(Geometry, Input and

Listing) for MULGRAPH

�Initial conditions �Temp-15oC�Pressure-I bar�Density-2500kg/m3


Numerical Reservoir Model Simulator�Two models were discretized with dimensions

750 m X 750 m and 1500 m X 1500 m

�Two rock types considered�Sedimentary layer (top)

�Granite layer (below)� Fractured zone named JJ layer (1990-2000 m)� Production and Injection well spaced at 100 m


Discretized Models


�The impacts of the cold injected water on the production well.

�The impacts of the rates of injection on enthalpy

�Procedure�Discretize model and 25 yrs runs of 500

time steps-AUTOUGH-2

�View the results using MULGRAPH�History matching simulations of enthalpy at

varying injection mass rate


Model Vertical Structure


Plot of Temperature VS Depth


Simulated Enthalpy History (Smaller model)


Simulated Enthalpy History(Bigger model)


Plan view of Temperature variation


Conclusion�Enthalpy varies with the injection rates

�Hydraulic fracturing creates permeability� Fluids flow is horizontal and vertical flows

�The technology tested at number of sites with different geology


References1. Beardsmore, G. (September 2007), “The Burgeoning Australian Geothermal Energy Australian Geothermal

Energy Industry”, Geo-Heat Quarterly Bulletin (Klamath Falls, Oregon: Oregon Institute of Technology. 28 (3) pp. 20-26.

2. Donald W. B, (2009) “ Hot Dry Rock Geothermal Energy:Important Lessons From Fenton Hill” Proceedings, Thirty-Fourth Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, February 9–11, 2009

3. Karner, S.L., (2005), “Stimulation Techniques Used In Enhanced Geothermal Systems” proceedings, 30th

Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, January 31-February 2, 2005

4. Pruess, K. and Narasimhan, T. N (1985) “A practical method for modeling fluids in fractured porous media” SPE J (Feb.1985) 14-26

5. Pruess, K. et.al. (Nov, 1999), TOUGH2—User’s Guide, Version 2.0. Earth Science Division. LBNL-43134. University of California, Berkeley, California

6. Tenzer H. (2002): “Development of Hot Dry Rock Technology, International Workshop on Hot Dry Rock Technology”: pp 213-226

7. Tester, J W. et al (Massachusetts Institute of Technology) (2006).” The Future of Geothermal Energy- Impact of Enhanced Geothermal System (EGS) on United States in the 21st Century” Idaho Falls: Idaho National Laboratory ISBN 0-615-13438-6. Retrieved 2007-02

8. Yeo, I. W., M. H. De Freitas, and R. W. Zimmerman, 1998. “Effect of Shear Displacement on the Aperture and Permeability of a Rock Fracture.” International Journal of Rock Mechanics and Mining Sciences, v.35, pp.1051–1070.


END

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