Play Fairway Analysis of Steptoe Valley, Nevada: Integrating Geology, Geochemistry, Geophysics, 3D Modeling, and Heatflow Modeling

Date and Time
October 22, 2020 03:45 PM (PDT)–04:45 PM (PDT)

Steptoe Valley was one of five areas selected for detailed study from an initial 96,000 km2 Nevada play fairway study completed in 2015. The purposes of conducting the detailed field studies were to increase the level of data resolution and increase the quality or confidence in the inputs in this play fairway analysis. The Steptoe Valley study area boundaries were selected 1) to include several highly favorable areas identified in the initial regional study, 2) where substantial subsurface data were available, including existing borehole data and 2D seismic reflection profiles, and 3) to include the deep part of northern Steptoe Valley that has been the focus of sedimentary basin geothermal resource studies. New detailed mapping of the range-front fault system provided better resolution with conspicuous steps in the main fault trace ranging up to 500 m. Nearly 300 new gravity stations were collected and merged with existing data to support multiple types of models. Nearly 200 km of seismic reflection data were interpreted with control provided by mapping, well data, and gravity modeling. 3D geologic modeling was employed to integrate the geologic map data, well data, and 2D reflection profiles to map the intrabasinal fault architecture, and to support a study area-wide conductive heat flow model. Twelve favorable structural settings were defined from the new 2D and 3D geologic map. Two of these are associated with known geothermal areas (Monte Neva and Cherry Creek Hot Springs), the rest may host undiscovered blind resources. GeoT equilibrium modeling of fluids from Cherry Creek and Monte Neva Hot Springs both indicate that power capable (>130 °C) reservoirs are possible.

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