Controlled Source Frequency-Domain Magnetics At Salt Wells Area (Montgomery, Et Al., 2005)

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Exploration Activity: Controlled Source Frequency-Domain Magnetics At Salt Wells Area (Montgomery, Et Al., 2005)

Exploration Activity Details
Location Salt Wells Area
Exploration Technique Controlled Source Frequency-Domain Magnetics
Activity Date 2004 - 2004

Usefulness useful
DOE-funding Unknown

Exploration Basis
AMP Resource contracted Willowstick Technologies, LLC to conduct a Controlled Source-Frequency Domain Magnetics (CS-FDM) geophysical investigation at Salt Wells in order to characterize and delineate areas showing the greatest concentrations and highest temperatures of geothermal groundwater. The investigation also sought to map blind faults beneath the site that were inferred to contain and conduct high temperature geothermal fluids. The objectives were intended to aid in site selection of production and injection wells for a planned AMP Resources power plant, in order to optimize hot water production from the geothermal resource.
The CS-FDM survey targeted geothermal groundwater within a 700x1000 m area, across a depth interval from approximately 100 to 170 m below the land surface. Subsurface faults within this area were suspected to have the greatest amount of geothermal fluid flow at the site. Details of the antenna/electrode configuration and magnetic field sensor station spacing are reported by Montgomery et al. (2005). After raw data reductions and background interference corrections were applied to some 450 magnetic field measurements, data were integrated into a contoured map of conductive highs and lows that equate to areas of high or low groundwater saturation. Results indicate that migration of geothermal waters is strongly affected by subsurface features that inhibit fluid flow and concentrate thermal waters along east-west channels that likely represent faults that cut the subsurface basalt sequence. The inhibiting feature and associated conductive low near the basin’s southern margin appears to correlate roughly with the mapped northwest-striking dextral fault that we tentatively associate with the Walker Lane in this review. This association suggests that major strike-slip faults in the Great Basin may act as barriers to fluid flow along their strike, possibly due to the accumulation of clay-sized fault gouge along these structures. Geothermal waters are inferred to ascend along permeable fracture zones produced by the intersecting faults that form Simpson Pass, and then flow laterally towards the northeast along channels and/or blind fault intersections in the fractured basalt. Production well sites recommended by Willowstick based on the survey results were drilled by AMP following completion of the exploration work, and showed favorable flow rates exceeding 170 L/s with no drawdown and temperatures > 140oC.


Additional References