Flow Test At Fenton Hill HDR Geothermal Area (Brown, 1994)
From Open Energy Information
Exploration Activity: Flow Test At Fenton Hill HDR Geothermal Area (Brown, 1994)
The LTFT of the Phase II reservoir was conducted in two phases, for 16 weeks from April to July in 1992 and again for 8 weeks concluding in May of 1993.
Two reservoirs were created to test the feasibility of extracting a thermal resource from hot rocks that lack in-situ geothermal fluids. The second, deeper Phase II reservoir was created by pressure-stimulation and hydraulic fracturing of jointed granitic rocks at a depth of 3500 m with an average temperature or 235°C. This reservoir was flow tested in 1986 during the Initial Closed-Loop Flow Test (ICFT), and again from 1992 to 1993 during the Long-Term Flow Test (LTFT). During the first phase of the LTFT, the Phase II reservoir was operated at approximately 6.8 L/s injection rate and 10 MPa backpressure. Between the two phases of the LTFT, a 6 week Interim Flow Test (IFT) was conducted at backpressures of 10 MPa and lower injection rates 4.3 L/s (22 MPa), in addition to two months of testing in November and December of 1992 where the reservoir was operated under injection rates of 7.1 L/s and backpressures of 12 MPa. The second phase of the LTFT was conducted using injection rates of 7.3 L/s and backpressures of 15 MPa. Injection pressures were only varied during the IFT-all other flow tests were run using 27 MPa injection pressure. The temperature of the injected water used during each test was approximately 18°C. During the first phase of the LTFT, waters were produced from well EE-2 at flow rates of 5.7 L/s and temperatures of 183°C. Under the reduced injection pressures of the IFT, production flow rates and temperatures were 3.9 L/s and 165°C, respectively. Further increasing the backpressure to 15 MPa resulted in a return to production flow rates of 5.7 L/s at temperatures of 183°C. During the second phase of the LTFT (the highest backpressure test), flow rates were 5.3 L/s at temperatures of 177°C.
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