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The Shale Spectrum: Interdisciplinary understanding across oil shale, oil-bearing
shale and gas shale plays
Jeremy Boak, J. Frederick Sarg, Steven Sonnenberg
Center for Applied Petroleum Systems Analysis & Research
Department of Geology & Geological Engineering
Colorado School of Mines
The Center for Oil Shale Technology & Research& The Colorado School of Mines
31st Oil Shale Symposium October 17-21, 2011 at the Cecil H. & Ida Green Center, Colorado School of Mines, Golden, Colorado
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Shale and Mudstone Plays
• Steady demand and new technology drive interest in turning source rock formations into reservoirs
• Mudstone or shale, organic richness is key
• Seeking hydrocarbons that have not migrated far from their sources
• Is there oil that is not kerogen oil?
2
3
Petroleum Systems Perspective
Source - USGS, Petroleum Systems and Geologic Assessment of Oil and Gas in the
Uinta-Piceance Province , Utah and Colorado
Gas shale & Shale gas
Oil-bearing shale & shale-hosted oil
Oil shale & shale oil
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4
Bakken – Green River Comparison
0
500
1000
1500
2000
2500
3000
3500
0 10 20 30 40TOC (wt %)
Green River
Bakken
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5
Technical Complexity; Geologic Diversity
• Development of oil shale requires artificial heating of immature kerogen, at surface or in situ
• Development of oil-bearing shale and gas shale depends upon more traditional methods
– applied in much more complex ways
– to kerogen that ranges from incipiently mature to overmature
• What can oil shale development add to the conversation?
• Rocks containing these hydrocarbons span same range of compositions and share rock textures and features
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6
Shale and Mudstone Mineralogy
Carbonate
Quartz +
FeldsparClay Minerals
Average Shale (1975)
Bakken
Barnett
U. Green River
L. Green River
Chinese Oil Shale
Thailand Oil Shale
Polish Gas Shale
Duvernay
Muskwa
Besa R. Lower black shale
Besa R. Upper black shale
Fort Simpson
Q+F=Clay
Carbonate/Clastic
calcareous/ dolomitic mudstone
argillaceous mudstone
siliceousmudstone
argillaceous marlstone siliceous
marlstone
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What Can Oil Shale Add?
• Physical properties of rocks across range of organic richness and mineralogic variety
• Understanding of kinetics of oil generation
• Understanding of geologic environments of organic-rich sediment
– Variation of organic matter type
– Variation of mineralogy
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8
Physical Properties of Shale Systems
• All are very tight, impermeable mudstone and siltstone
• Production of hydrocarbons, natural or synthetic, depends on fracturing rock to drain the products
• Properties measured across temperature and pressure range needed
– to describe mechanisms of generation, migration and trapping of oil and gas
– to understand fracturing behaviour for field development
• Understanding properties of broad class of rocks informally called shale can be complementary
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Shale Properties Depend on Organic Richness
0
10
20
30
40
50
0 5 10 15 20 25 30
GPa
Oil Yield (wt %)
Young's Modulus
Bulk Modulus
Shear Modulus
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10
Fracture Properties Determine Producibility
Chart from Core Labs
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11
Pressure Gradient Map of Altamont-Bluebell Field
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12
Kinetics of Oil Generation
• Understanding kinetics of generation requires experiments at temperatures in the range of in situ retorts
• These experiments are important to understanding both synthetic and natural systems
• Can these models constrain models for generation in natural systems?
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13
Experimental Range for Pyrolysis
• Slow heating
– Changes relative reaction rates
– Affects volatilization of fragments
• Wide range of rates
– From ICP
– To surface retorting (e.g. Fischer Assay)
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Heating Rate (oC/d)
Oil A
PI
Oil API Decrease with Heating Rate
0.1 1 10 100 1,000 10k 100k
40
35
30
25
20
Oil API Gravity
Green River
Fischer Assay
ICP
1 year
5 days
1 day
1 hour
??
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Diversity of Oil Shale Kinetic Models
14
0
25,000
50,000
75,000
100,000
125,000
Scheme 1 Scheme 2 Scheme 3
BO
E
Gas
Light Oil
Heavy Oil
Scheme 1
Produced
Unproduced
Unreacted
Residue
Scheme 2
ProducedUnproducedUnreactedResidue
Scheme 3
Produced
Unproduced
Unreacted
Residue
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Understanding Environments of Formation
• Behavior depends on organic content
• Also on mineralogic composition and variability
• Properties result in turn from
– Sedimentary history
– Depositional environments under which they formed
– Diagenetic alteration following deposition
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Fischer Assay Oil Gravity
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0.86
0.87
0.88
0.89
0.90
0.91
0.92
0.93
0.94
0.95
R8
A G
roo
ve
Mah
oga
ny
B G
roo
ve R6 L5 R5 L4 R4 L3 R3 L2 R2 L1 R1 L0 R0
Spe
cifi
c G
ravi
ty
Unit
John Savage 24
Colorado 1
Corehole CR-2
Corehole CR-1
Shell 23-X2
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CR-2 Mineralogy (Dean, Howell, Pitman, 1981)
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Top R5
Top R2
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USBM 01A Well:Salinity, Redox, Oil & Mineral Properties
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CAPSAR Research Consortia
• We have developed three separate research consortia on shale systems
– Green River Formation oil shale
– Bakken shale-hosted oil play
– Niobrara mudstone oil play
• Common ground for each of these consortia include:
– characterization of sedimentologic and petrologic features to create an integrated geologic framework
– measurement of critical properties relating to seismic characterization, rock strength and fracturing behavior
– modeling of rock mechanical behaviour under stress
• Understanding shale systems generically can provide synergistic insights across plays
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Conclusions
• Integrated analysis pays general benefits
– Even of unusual basins like the Green River Formation basins
– Connections between lacustrine and marine?
– Some oil shale basins of ambiguous origin
• Stratigraphic, mineralogic, chemical characterization supports engineering property determination
• Kinetic models have yet to capture behavior across T and time scales
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Shale Play Terminology
Source - USGS, Petroleum Systems and Geologic Assessment of Oil and Gas in the Uinta-Piceance Province , Utah and Colorado
Gas shale & Shale gas
Oil-bearing shale & Shale-hosted oil
Oil shale & shale oil
21
22
Shale and Mudstone Mineralogy
Carbonate
Quartz + FeldsparClay Minerals
Average Shale (1975)
Bakken
Barnett
U. Green River
L. Green River
Chinese Oil Shale
Thailand Oil Shale
Polish Gas Shale
Duvernay
Muskwa
Besa R. Lower black shale
Besa R. Upper black shale
Fort Simpson
Q+F=Clay
Carbonate/Clastic
calcareous/ dolomitic mudstone
argillaceous mudstone
siliceousmudstone
argillaceous marlstone
siliceous marlstone
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