| Abstract |
The WHOLESCALE acronym stands for Water & Hole Observations Leverage Effective Stress Calculations and Lessen Expenses. The goal of the WHOLESCALE project is to simulate the spatial distribution and temporal evolution of stress in the geothermal system at San Emidio in Nevada, United States. To reach this goal, the WHOLESCALE team has developed a methodology to incorporate and interpret data from four methods of measurement into a multi-physics model that couples thermal, hydrological, and mechanical (T-H-M) processes. The WHOLESCALE team includes personnel from two universities, two national laboratories, and one industry partner. The WHOLESCALE team has taken advantage of the perturbations created by changes in pumping operations during planned shutdowns in 2016, 2021, and 2022 to infer temporal changes in the state of stress in the geothermal system at San Emidio. The observations support the working hypothesis that increasing pore-fluid pressure reduces the effective normal stress acting across fault zones. During normal operations, pumping in deep production wells decreases the pore-fluid pressure and increases the effective normal stresses on faults, thus modulating microseismicity. During planned shutdowns, the cessation of production increases pore-fluid pressure and reduces the effective normal stress. In this paper, we summarize the conclusions of the WHOLESCALE project. The work presented herein has been funded in part by the Office of Energy Efficiency and Renewable Energy (EERE), U.S. Department of Energy, under Award Number DE-EE0009032. We acknowledge image data acquired by the TerraSAR-X and TanDEM-X satellite missions operated by the German Space Agency (DLR). These data were used under the terms and conditions of Research Project RES1236. Image data were also acquired by the SENTINEL-1 satellite mission operated by the European Space Agency (ESA). |