Egs Exploration Methodology Development Using the Dixie Valley Geothermal Wellfield as a Calibration Site, a Progress Report

An Engineered Geothermal System (EGS) exploration methodology is being developed using the Dixie Valley geothermal system in Nevada as a field laboratory. This area was chosen as the test site because its has an extensive public domain database and deep geothermal wells allowing for calibration of the developed methodology. The calibration effort is focused on the Dixie Valley Geothermal Wellfield (DVGW), an area with 30 geothermal wells. Calibration will be based on cross-correlation of qualitative and quantitative results with known well conditions. This project is structured in the following manner (Task 1) review and assess existing public domain and other available data (baseline data); (Task 2) develop and populate a GIS-database; (Task 3) develop a baseline (existing public domain data) geothermal conceptual model, evaluate the geostatistical relationships between the various data sets, and generate a Baseline EGS favorability map from the surface to a 5-km depth focused on identifying EGS drilling targets; (Task 4) collect new gravity, seismic, magneto-tellurics (MT), geologic, and geochemical data to fill in data gaps and improve model resolution; and (Task 5) update the GIS-database for the newly acquired data and repeating the elements of Task 3 incorporating the baseline and new data to generate an Enhanced EGS Favorability Map. Innovative aspects of this project include: (1) developing interdisciplinary method(s) for synthesizing, integrating, and evaluating geoscience data both qualitatively and quantitatively; (2) demonstrating new seismic techniques based on ambient noise which is a passive survey not requiring local earthquakes and is a relatively inexpensive method to image seismic velocity, attenuation, and density; (3) determining if seismic data can infer temperature and lithology at depth; (4) extending 2D MT modeling/mapping to 3D MT; (5) generating a MT derived temperature map; and (6) jointly analyzing gravity, magnetic, seismic, and MT data to the degree feasible to reduce non-uniqueness of geophysical data. Tasks 1 and 2 have been completed except for thermal modeling. The baseline geothermal conceptual model, the geostatistical analysis, and formulation of an EGS Favorability Map are in progress and expected to be completed by the time of the annual meeting. Task 4 is underway to collect primarily higher resolution geophysical data. The new surveys will cover an area slightly larger than the 50km x 50km Project Area centered over the DVGW. Selected results of the data review, the baseline conceptual model, geostatistical correlations between various data sets, the Baseline EGS Favorability Map and the new planned surveys will be discussed.