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Phase 2 Update for the Fallon FORGE Site, Nevada, USA
Bridget Ayling1, Douglas Blankenship2, Patrick Sullivan2, Mack Kennedy3, Ernest L. Majer3, Maryann Villavert3,
Eric Sonnenthal3, Jennifer Tang3, Pat Dobson3, Nicholas Hinz4, James Faulds4, William Hammond4, Elijah Mlawsky4,
Kelly Blake5, Andrew Tiedeman5, Andrew Sabin5, Mike Lazaro5, John Akerley6, Josh Nordquist6, Matthew Sophy6,
Drew L. Siler7, J. Ole Kaven7, Geoffrey Phelps7, Stephen Hickman7, Jonathan Glen7, Colin Williams7,
Ann Robertson-Tait8, Logan Hackett8, Will Pettitt9, Azadeh Riahi9, Derrick Blanksma9, Branko Damjanac9, Jim Hazzard9,
Mariana Eneva10, Jeffrey B. Witter11, John Queen12, Mark Fortuna13.
1 Great Basin Center for Geothermal Energy, University of Nevada, Reno, Nevada
2 Sandia National Laboratories, Albuquerque, New Mexico
3 Lawrence Berkeley National Laboratory, Berkeley, California
4 Nevada Bureau of Mines and Geology, University of Nevada, Reno, Nevada
5 U.S. Navy Geothermal Program Office
6 Ormat Nevada Inc.
7 U.S. Geological Survey, Menlo Park, California
9 Itasca Consulting Group, Inc.
10 Imageair Inc. Nevada
11 Innovate Geothermal Ltd.
12 Hi-Q Geophysical Inc., Oklahoma
13 MAF Seismic, LLC
Keywords: FORGE, geothermal energy, Fallon, Nevada, EGS
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 [3DEC] 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.
Left: Simulated (synthetic) microseismicity from Stage 1 of hydraulic treatment. Blue is injection well showing six stages along the sub-horizontal section, with four injection positions per stage. Red is production well for the side-by-side conceptual design. Microseismicity is color scaled to moment magnitude, green to red, in the range -3 to 1. 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.
PROCEEDINGS, 43rd Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, February 12-14, 2018 SGP-TR-213