Development of a Geostatistical Thermal Model of the Great Basin Region, Western USA

Abstract

The Great Basin region is a world-class geothermal province, spanning approximately 500,000 km² and including much of the states of Nevada and Utah, and parts of Idaho, Oregon and California. Currently, the Great Basin has ~ 1,100 MWe installed geothermal power generation capacity, and is estimated to have as much as ~10,000 MWe currently undiscovered potential (mean estimate). A major exploration challenge in the Great Basin is locating blind geothermal systems: as much as 2/3 of currently discovered systems are thought to be blind (i.e. have no surface thermal expressions). As such, understanding the subsurface temperature regime is imperative to guide more efficient geothermal exploration efforts in the basin, and improve exploration success. To date, substantial work and research has gone into studying temperatures in the basin by drilling temperature gradient wells, taking two-meter temperature probe measurements, and creating temperature maps at varying depths across the basin. However, to date, regional map products have been 2D in nature, and there has been no production of a true 3D temperature study of the Great Basin. Here, we present a 3D statistical model of the sub-surface temperatures in the area used for a previous Play Fairway Analysis in the Great Basin, by applying innovative geostatistical methods (such as sequential Gaussian simulation (SGSIM) for interpolation of the temperature field) to existing, publicly available temperature datasets. We also attempt to capture the effect of geologic structures on temperatures, given the known strong structural control on geothermal system occurrence in the Great Basin.