Spatio-Temporal Analysis of Deformation at San Emidio Geothermal Field, Nevada, USA Between 1992 and 2010

Abstract

Deformation has been observed at San Emidio geothermal field in Nevada using geodetic and seismic instruments. These observations point to an interaction between operations at the power plant and stress in the subsurface. In particular, cooling of the reservoir (via injected cooled water) and localized pressure changes (due to pumping and injection) contribute to the stress state at San Emidio. Our WHOLESCALE proposal has been recommended by the Geothermal Technologies Office of the U.S. Department of Energy for negotiation of a financial award. Indeed, 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 a geothermal system. To reach this goal, the WHOLESCALE team proposes to develop a methodology that will incorporate and interpret data from four methods of measure¬ment into a multi-physics model that couples thermal, hydrological, and mechanical (T H M) processes over spatial scales ranging from the diameter of a borehole (~0.1 m) to the extent of the entire field (~10 km) and temporal scales ranging from the duration of a micro-seismic event (~1 second) to the typical lifetime of a producing field (3 decades).