Geology of Injection Well 46A-19RD in the Coso Enhanced Geothermal Systems Experiment
- Key words
- Coso; Coso, Enhanced Geothermal Systems, EGS, geology, paragenesis
- Location
- Coso, California
- Conference
- Geothermal Resources Council Transactions
- Year
- 2006
- Session
- HDR/EGS; geology; paragenesis
- Language
- English
Abstract
The Coso Geothermal Field is a large, high temperature system located in California on the western edge of the Basin and Range province. Well 46A- 19RD, located in the southwestern portion of this field is currently the focus of a DOE-funded Enhanced Geothermal Systems (EGS) project. Petrologic and petrographic investigations of the well show that quartz diorite and granodiorite are dominant lithologies. Dikes of granophyre, containing phenocrysts of plagioclase, potassium feldspar, and quartz were encountered at approximately 1438-1457 m and 3459.5-3505.2 m. In contrast to the other rock types, the dikes are weakly altered. Granodiorite, in contact with the granophyre at 3474.7 m, is faulted and hydrothermally altered. This fault zone is a prime target for stimulation.
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