A DOE-Industry cost-shared project is underway at Desert Peak East, located within the Hot Springs Mountains, northwestern Churchill County, approximately SO miles (80.S km) northeast of Reno, Nevada. The potential reservoir under investigation is contained within pre-Tertiary metamorphic and granitic rocks with temperatures exceeding 400°F (204°C). The purpose of the geologic study is to determine the lateral and vertical extent of basement lithologies, and the character and mineralogy of natural fracturing in the rocks to identify suitable targets for hydrofracturing and stimulation in subsequent phases of this enhanced geothermal system (EGS) project.

The Rye Patch geothermal field is a classic Basin-and-Range resource with a "blind" anomaly, moderate temperature and "deep circulation" as the source of heat. This paper presents a conceptual model of the field based on lithologic, geophysical and temperature logs as well as production, injection and pressure interference data from 8 deep wells drilled to date. For the hottest well in the field (405°F), we have conducted well bore heat transfer modeling to resolve a major observed discrepancy between the flowing and static temperature profiles, the latter being shown to be affected by downflow of cooler water. The conceptual model has been developed to fit all available resource information, and had been used to estimate reserves: a minimum of 36 M Wand a most-likely level of 64 MW for a 20-year project life. Based on well test data, the maximum gross power production capacity from the existing wells is estimated at 21 MW. The existing wells are capable of supplying the 12.5 MW plant installed at the site if one or two additional wells are drilled for injection.