Geothermometry At Salt Wells Area (Edmiston & Benoit, 1984)

GEOTHERMAL ENERGY

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Exploration Activity: Geothermometry At Salt Wells Area (Edmiston & Benoit, 1984)

Exploration Activity Details
Location	Salt Wells Geothermal Area
Exploration Technique	Geothermometry
Activity Date	1980 - 1984
Usefulness	useful
DOE-funding	Unknown

Exploration Basis

The blind Salt Wells geothermal system was first identified when Anadarko Petroleum Corporation drilled slim hole and geothermal exploration wells at the site in 1980. Two reports detail the results of this drilling activity. This paper seeks to (1) describe several moderate-temperature (150-200°C) geothermal systems discovered and drilled during the early 1980’s that had not been documented previously in the literature, (2) summarize and compare chemical and temperature data from known moderate- to high-temperature (>200°C) in the region, and (3) to comment on the accuracy of the Na-K-Ca and silica geothermometers typically used to estimate reservoir temperatures.

Notes

Geothermal surface indications at Salt Wells are described as scant, consisting only of a cold NaCl spring and of sinter deposited from hot springs that were allegedly active during the late 1880s. A 46 km2 thermal anomaly was defined at the Salt Wells geothermal area that extends over 12 km to the south to the Cocoon Mountains. About half of this anomaly is underlain by shallow aquifers that exhibited temperatures of >100°C at less than 100 m depth. In 1980, Anadarko Petroleum Corporation drilled an exploratory well to 2,591 m depth in Simpson Pass, in an attempt to intersect a deep fracture system predicted by geological and geophysical studies to occur within a large horst block between two active fault systems. Major cation and anion geochemical data used for geothermometry were taken from a variety of sources, some of which were of questionable quality. Na-K-Ca geothermometry of the cold spring yielded a temperature of 207°C. Geothermometers applied to waters from shallow depths in the well indicated silica temperatures of 220°C and Na-K-Ca temperatures of 235°C. Na-K-Ca temperatures of deeply sourced waters were slightly lower at 205°C. Silica and Na-K-Ca temperatures from shallow samples were significantly higher than measured temperatures in the well, presumably due to rapid reequilibration of the fluid as it cooled along its path to the surface. The Na-K-Ca temperature from the deeply sourced sample was also artificially high, but showed better agreement with maximum temperatures measured in the well.

References

• R.C. Edmiston, W.R. Benoit (1984) Characteristics of Basin and Range Geothermal Systems with Fluid Temperatures of 150°C to 200°C