Resource Evaluation Case Study for Surprise Valley, California

Abstract

Warner Mountain Energy (WME) sited, drilled, and flow tested an exploratory well (well WME-E1) in Surprise Valley, Modoc County, California which was successful in finding and characterizing a commercial grade geothermal resource. The resource is hosted in the Surprise Valley Known Geothermal Resource Area (KGRA) near the Surprise Valley Hot Springs resort (SVHS) which has great geothermal potential and has been studied for many years. Currently, the SVHS area utilizes shallow geothermal resources for space heating and balneology. Well WME-E1 was drilled into a deeper and hotter resource and was flow tested. A highly permeable and productive feedzone was encountered within fractures at ~2300 feet below ground surface (bgs). Downhole flowing temperature was 225 °F (liquid) and the maximum static downhole temperature was 230.5 °F. Reservoir permeability is extremely high. Under wide open flow, the well delivers 500 gpm of self-sustained artesian flow at a wellhead pressure of 1 psia. Data were analyzed and used to develop and calibrate a numerical model using TETRAD simulation software. Forecasts from the calibrated numerical model show that with additional wells, much higher levels of production are achievable and sustainable. This paper describes the analyses and simulation techniques used, their results and implications on the resource size and potential.