DEEP PERMEABLE STRATA
GEOTHERMAL ENERGY
A Means To Extend Geothermal Energy Production
To Deep Sedimentary Basins
Dr. Richard J. Erdlac, Jr.
The University of Texas of the Permian Basin
Center for Energy & Economic Diversification
Douglas B. Swift
Petroleum Consultant
Concept Devised & Initiated By:
Mr. Douglas B. Swift
Dr. Richard J. Erdlac, Jr.
West Texas Earth Resources Institute
World Geothermal Provinces
U.S. Geothermal Provinces
United States Geothermal Electric Power Generation Potential
(GeoPowering The West - DOE, 2000)
Top 3 States: Nevada, California, Utah
Other High Potential States: Idaho, Hawaii, New Mexico, Oregon,
South Dakota, Texas, and Wyoming
“Texas does not have the sort of readily
accessible high-temperature hydrothermal
resource that can be used to generate electricity.”
“Geysers, hot springs, volcanoes, and seismic activity,
all of which are noticeably absent in Texas, mark
such regions.”
Texas Renewable Energy Resource Assessment, 1995
Statement did not envision DPSGE.
Deep sedimentary basins, (e.g the Delaware, Val
Verde, Anadarko, Appalachian) contain high
thermal reservoirs which can be tapped for
geothermal power generation.
Structures in the Delaware and Val Verde Basins
have been prolific for natural gas production.
These wells demonstrate extensive, highly porous
and permeable strata.
Geothermal grade temperatures are readily
apparent from DST data, BHT tests, and less
reliable electric log measurements.
Potential U.S. DPSGE Sedimentary Basins
Texas
Oil And Gas
District
Boundaries
Deep wells (Ellen>15,000’)
in central Delaware Basin.
Well control courtesy of
GDS; Mapped with
Geographix.
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- 15000
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- 15000
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Subsurface map of
borehole temperature
(BHT) data from oil and
gas wells in the Permian
Basin. Black dots: BHT
150oF (65oC). Blue dots:
BHT = 151oF to 179oF
(66oC to 81oC). Green
dots: BHT = 180oF to
280oF (82oC to 142oC).
Red dots: BHT 290oF
(143oC). Isotherm
contours are in thousands
of feet below surface. The
dark gray area represents
the 150oF isotherm.
Adapted from Subsurface
Temperature Map of North
America (1976).
The basic requirements for an exploitable
DPSGE geothermal region are similar to
those for oil and gas exploration:
1) a sufficiently high geothermal gradient;
2) A significantly large, porous and
permeable reservoir to receive and heat
injection fluids;
3) A seal to contain the system.
120
100
80
60
40
20
0
0.
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0.
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0.
72
0.
78
0.
84
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90
0.
96
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02
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26
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56
Wells
Total Permian Basin
Temp. Grad.
Distribution of temperature gradient for wells within the Permian Basin (New Mexico and Texas).
Values given in degrees F/100 feet. Data source from the Geothermal Survey of North America.
AAPG, 1976.
Delaware - Val Verde Basins
10
6
4
2
0
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0.
66
0.
72
0.
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0.
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Wells
8
Temp. Grad.
Distribution of temperature gradient for wells within the Delaware and Val
Verde Basins. Values given in degrees F/100 feet. Data source from the
Geothermal Survey of North America. AAPG, 1976.
Deep Ellenburger Formation gas fields with BHTs
ranging from 115o to > 160oC (239o to >320oF) are
well documented.
These temperatures are sufficiently high to generate
live steam.
A number of the fields studied are prospective for
flash power generation. Most are particularly
attractive as sources for fueling binary systems.
5
4
3
2
1
0
0.
60
0.
66
0.
72
0.
78
0.
84
0.
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0.
96
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02
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14
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26
1.
32
1.
38
1.
44
1.
50
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56
Wells
Trans-Pecos
Temp. Grad.
Distribution of temperature gradient for wells within the Trans-Pecos region
of Texas. Values given in degrees F/100 feet. Data source from the
Geothermal Survey of North America. AAPG, 1976.
Geothermal Delivery Systems
Existing Plant Designs
Dry Steam Power Plants – use steam directly.
Flash Steam Power Plants – hot water under pressure (most
common).
Binary Cycle Power Plants – hot water through heat
exchanger.
Feedstock Systems – incremental heat in elevated water
temperatures.
New Plant Designs
Power Tube – iso-pentane & iso-butane into subsurface.
Water temperature (optimum range)
230o to 380o F (110o to 193o C)
Construction costs ~ $1500 per kW
including exploration and drilling.
10 Mw plant $15,000,000
(National Renewable Energy Laboratory, 1999)
Canyon Diablo Binary Geothermal Plant
Mammoth, California
Alternate Geothermal Technology – Power Tube
DEEP >4 KM (>13,000’)
PERMEABLE
STRATA
GEOTHERMAL
ENERGY
A
NEW
DAWN!