| Title | Reservoir Testing and Analysis at the Patua Geothermal Federal Unit, Northwestern Nevada |
|---|---|
| Authors | Combs, Jim; Peterson, Neil; Garg, Sabodh K.; Goranson, Colin |
| Year | 2012 |
| Conference | Geothermal Resources Council Transactions |
| Keywords | Patua reservoir; corehole drilling; well drilling and testing; geothermometers; conceptual model |
| Abstract | To better understand the geothermal reservoir underlying the Gradient Resources Inc. (GRI) leases at the Patua Federal Geothermal Unit and better define the geothermal fluids to be used as fuel to generate electricity, GRI has undertaken an extensive exploration program consisting of geological, geochemical, and geophysical surveys, core hole drilling, well drilling, well discharge testing and finally a 30-day flow and injection test. Based on the data obtained from the well drilling and testing, a conceptual model of the Patua Geothermal Reservoir has been developed. The subsurface stratigraphy consists of a sequence of volcanic rocks overlying naturally-fractured granitic rocks of the basement. The geothermal reservoir consists of naturally-fractured granitic rocks with high-permeability stress induced fractures striking along northeastern and orthogonal northwestern trends. Pressure interference data recorded by monitoring coreholes and wells during ongoing discharge testing supports the concept of the lack of interconnection between coreholes completed in the volcanic rocks and production wells completed in the underlying geothermal reservoir. Pressure interference data indicates the geothermal reservoir extends to at least ten (10) square miles. Based on the results and analysis of the extensive exploration program, in addition to well discharge and pressure interference testing while using the USGS “heat in place” with Monte Carlo simulation methodology, there is a 90% probability (P90) that the gross power generation capacity of the Patua Geothermal Reservoir is at least 207 MWgross, and a 50% probability (P50) it is more than 320 MWgross. |