The Basin and Range Dixie Valley Geothermal Wellfield, Nevada, USA-A test bed for developing an Enhanced Geothermal System exploration favorability methodology

摘要

The Dixie Valley Geothermal Wellfield (DVGW), a Basin and Range type system in central Nevada USA, is used as an exploration case history for Enhanced Geothermal Systems (EGS). It encompasses an area of approximately 170 km(2). The wellfield produces 67 MW of geothermal power and it contains a number of high temperature non-productive wells. This wellfield was chosen as the calibration site for the development of an EGS exploration methodology due to its extensive body of geoscience data and information on the geothermal system and most importantly, well results in the public domain. This existing body of data (ca. 2011) was in part re-interpreted to produce a baseline conceptual model in terms of a number of serial cross-sections for the available data sets: geology, seismic reflection, resistivity, temperature, gravity-magnetic, and p-wave velocity (Vp). The exploration methodology was calibrated against available geothermal well results. Basect on a comprehensive review of all available geoscience and well data, EGS favorability maps were generated, from +1 km above sea level (asl) to -4 km asl at 0.5 km intervals, for the three key EGS parameters of interest: rock type, temperature, and stress. Complimentary trust ("confidence-in-the-data-used") maps were also created at the same scale to, among other things, indicate where additional data may be required.