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Phase 2 Update for the Fallon FORGE Site, Nevada, USA
Bridget AYLING, Douglas BLANKENSHIP, and The Fallon FORGE Team
The Department of Energy (DOE) Frontier Observatory for Research in Geothermal Energy (FORGE) is to be a dedicated field laboratory where the scientific and engineering community can develop, test, and improve sub-surface technologies and techniques for the creation of cost-effective and sustainable enhanced geothermal systems (EGS) in a controlled environment. The establishment of FORGE will facilitate an understanding of the key mechanisms controlling a successful EGS. The Fallon FORGE site in Nevada is one of two sites that are still being evaluated as potential candidates for hosting the final FORGE laboratory. In Phase 1 of the FORGE initiative, the Fallon team reviewed extensive, pre-existing data including lithological, well log, and flow test results from deep wells within the Fallon FORGE footprint that penetrate the target reservoir, as well as a suite of geophysical, geochemical, geological, and hydrological data on and adjacent to the site. Such evaluation confirmed that the Fallon site is ideally positioned to host a sub-surface EGS laboratory, with low permeability, appropriate temperatures and depths (175-225°C, 1-4 km), no hydrothermal system, appropriate lithologies, and a favorable stress regime. In Phase 2, key activities included: securing additional environmental permits and initiating an EA; extensive outreach with key local, regional and state stakeholders; preparing our induced seismicity mitigation plan (ISMP); acquisition of seismic and geodetic baseline datasets (MEQ, GPS and InSAR); reprocessing and reinterpretation of preexisting seismic reflection profiles; acquisition of new, detailed gravity and magnetic data; refining our detailed 3D model of the site (originally constructed in Phase 1) based on the new geophysical data and reinterpreted seismic reflection profiles; geomechanical and reservoir modelling; and siting and drilling a deep well to provide additional certainty that the target reservoir has low permeability. This paper provides an overview of these Phase 2 activities at the Fallon FORGE site and how these activities have further improved our knowledge of site characteristics.
Bridget Ayling, Douglas Blankenship, Patrick Sullivan, Mack Kennedy, Ernest L. Majer, Maryann Villavert, Eric Sonnenthal, Jennifer Tang, Pat Dobson, Nicholas Hinz, James Faulds, William Hammond, Elijah Mlawsky, Kelly Blake, Andrew Tiedeman, Andrew Sabin, Mike Lazaro, John Akerley, Josh Nordquist, Matthew Sophy, Drew L. Siler, J. Ole Kaven, Geoffrey Phelps, Stephen Hickman, Jonathan Glen, Colin Williams, Ann Robertson-Tait, Logan Hackett, Will Pettitt, Azadeh Riahi, Derrick Blanksma, Branko Damjanac, Jim Hazzard, Mariana Eneva, Jeffrey B. Witter, John Queen, Mark Fortuna. (2018) “Phase 2 Update for the Fallon FORGE Site, Nevada, USA,” in Proceedings, 43rd Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, February 12-14, 2018 SGP-TR-213, 13 pages.
Left: Stimulated zone of joints after 30 minutes of modelled fluid injection in Stage 1 at the toe of a sub-horizontal well. Right: Stimulated joint network in Stage 1 overlain by simulated microseismicity. Joints are color scaled blue to red according to shear displacements induced by the hydraulic pressures.