In-situ stress and fracture permeability in a fault-hosted geothermal reservoir at Dixie Valley, Nevada
- Geological Survey, Menlo Park, CA (United States)
- Stanford Univ., CA (United States); and others
As part of a study relating fractured rock hydrology to in-situ stress and recent deformation within the Dixie Valley Geothermal Field, borehole televiewer logging and hydraulic fracturing stress measurements were conducted in a 2.7-km-deep geothermal production well (73B-7) drilled into the Stillwater fault zone. Borehole televiewer logs from well 73B-7 show numerous drilling-induced tensile fractures, indicating that the direction of the minimum horizontal principal stress, S{sub hmin}, is S57{degrees}E. As the Stillwater fault at this location dips S50{degrees}E at {approximately}53{degrees}, it is nearly at the optimal orientation for normal faulting in the current stress field. Analysis of the hydraulic fracturing data shows that the magnitude of S{sub hmin} is 24.1 and 25.9 MPa at 1.7 and 2.5 km, respectively. In addition, analysis of a hydraulic fracturing test from a shallow well 1.5 km northeast of 73B-7 indicates that the magnitude of S{sub hmin} is 5.6 MPa at 0.4 km depth. Coulomb failure analysis shows that the magnitude of S{sub hmin} in these wells is close to that predicted for incipient normal faulting on the Stillwater and subparallel faults, using coefficients of friction of 0.6-1.0 and estimates of the in-situ fluid pressure and overburden stress. Spinner flowmeter and temperature logs were also acquired in well 73B-7 and were used to identify hydraulically conductive fractures.
- DOE Contract Number:
- FG07-96ID13463
- OSTI ID:
- 602665
- Report Number(s):
- CONF-971048-; TRN: 98:001318-0026
- Resource Relation:
- Conference: Geothermal Resources Council (GRC) annual meeting, San Francisco, CA (United States), 12 Oct 1997; Other Information: PBD: 1997; Related Information: Is Part Of Meeting the challenge of increased competition; PB: 665 p.
- Country of Publication:
- United States
- Language:
- English
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