| Title | THE UTAH FRONTIER OBSERVATORY FOR GEOTHERMAL RESEARCH (FORGE): A LABORATORY FOR EGS DEVELOPMENT |
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| Authors | J. Moore, R. Allis, K. Pankow, S. Simmons, J. McLennan, P. Wannamaker, W. Rickard, R. Podgorney |
| Year | 2017 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | FORGE, Milford, Utah, Enhanced Geothermal Systems |
| Abstract | The U.S. Department of Energy is sponsoring the FORGE (Frontier Observatory for Research in Geothermal Energy) initiative to bring Enhanced Geothermal System (EGS) development to commercial viability and visibility. The project will create a controlled environment where EGS technologies can be developed and tested. The Utah FORGE site, one of two sites being considered, is located in central Utah, 350 km south of Salt Lake City. Since the 1970s, more than 100 wells, the deepest to 3.8 km, have been drilled in the vicinity of the site. Well logs, detailed geologic mapping, geophysical surveys and seismic data provide information on temperatures, thermal gradients, rock types, and in-situ stresses. High angle, northeast-trending faults that formed during east-west extension offset the alluvium and recent sinter deposits but these do not extend into the FORGE site. Thirty years of monitoring indicates that natural seismicity surrounding the FORGE site is low. The data indicate the site is underlain by large volumes of Tertiary granite and Precambrian gneiss with temperatures from 175–225°C at depths of 2 to 4 km. Fault orientations, borehole breakouts, and earthquake solutions indicate the maximum horizontal stress is NNE-SSW. The project is being conducted in multiple phases. Phases 1 and 2A included project planning and review of potential environmental and cultural constraints. None that could adversely affect the project were identified. Phase 2B includes drilling a 2.1 km deep well to determine in-situ stresses, permeability, lithology and temperature within the thermal reservoir. Preliminary results from this well will be presented. At the conclusion of Phase 2B, a final site for the FORGE laboratory will be selected. In subsequent phases, the supporting infrastructure will be built and wells for injection and production will be drilled, stimulated and tested. |