211-4 USGS Provisional Assessments of Enhanced Geothermal Systems: Great Basin Results and Plans for Future Assessments

Session: Geothermal Resources Research

Presenting Author:

Justin Birdwell

Authors:

Birdwell, Justin E.¹, Burns, Erick R. ², DeAngelo, Jacob³, Gardner, Rand D. ⁴, Gelman, Sarah E. ⁵, Williams, Colin F. ⁶

(1) U.S. Geological Survey, Central Energy Resources Science Center, Denver, CO, USA, (2) U.S. Geological Survey, Geology, Minerals, Energy, and Geophysics Science Center, Moffett Field, CA, USA, (3) U.S. Geological Survey, Geology, Minerals, Energy, and Geophysics Science Center, Moffett Field, CA, USA, (4) U.S. Geological Survey, Central Energy Resources Science Center, Denver, CO, USA, (5) U.S. Geological Survey, Central Energy Resources Science Center, Denver, CO, USA, (6) U.S. Geological Survey, Minerals Resources Program, Moffett Field, CA, USA,

Abstract:

A recent USGS provisional assessment of electric grade (>90°C) geothermal resources in the Great Basin that could be developed using an enhanced geothermal systems (EGS) approach generated a best estimate of 135 GW electric-power generation capacity from high-temperature, low-permeability rock formations at depths ≤6 km using current technology. The assessment used an updated heat flow analysis of the Great Basin to generate a 3D temperature model for estimating power density in the assessed rock volume. To estimate the amount of electricity that could be generated from recovered heat, an idealized hypothetical development approach was utilized that involved systems of injection and extraction wells connected by engineered fractures. The analysis included estimated efficiencies for heat recovery and heat-to-electricity conversion as well as assumptions regarding the fraction of viable rock volume for development and an engineered reservoir spacing factor. While the estimated EGS potential is only 0.5% of the accessible electric-grade resource base, this represents approximately 10% of current total U.S. power production capacity.

The next areas that will be focused on for assessment of EGS potential are in petroliferous sedimentary basins across the conterminous United States. USGS scientists have recently developed calibrated thermal models for several U.S. basins, including the Williston, onshore Gulf Coast, Denver-Julesburg, and Upper Colorado River Basins. For those efforts, collections of drilling data from oil and gas development are being utilized to build 3D basin models that incorporate a variety of geologic data and measured subsurface temperatures. Bottom-hole temperatures are corrected using a heat flow modeling approach that accounts for depth and rock properties. The thermally calibrated basin models are then used to identify potentially recoverable and accessible electric-grade geothermal resources. Several useful outputs can be extracted from 3D basin models including: (1) temperature maps at depths of interest, (2) depth-to-temperature maps for different grades of geothermal resources, and (3) maps of formations present at selected depth-temperature combinations. For USGS regional geothermal assessments, these outputs provide the basis for differentiating geothermal resource grade and estimating the total resource in particular formations or intervals, which may have different development potential based on the availability of natural permeability or will require stimulation.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9317

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