Thursday, February 23, 2012

Safford basin CO2 sequestration potential

AZGS has released a new report “Geologic Evaluation of the Safford Basin for Carbon Dioxide Sequestration Potential.” The 175-page report by AZGS geologist Brian Gootee includes a compilation and characterization of available geologic and well-log data that provides for detailed structural and stratigraphic analyses of the deep Safford Basin. The report is accompanied by a regional geologic map and map plate with 17 cross-sections profiling basin geometry. [Right, Safford basin outlined in red. From the report]

The Safford basin is filled with unconsolidated sediments and is roughly 155 miles long, 12 to 16 miles wide, has an average depth of 6,500 to 9,800 ft., and a maximum depth of 11,500 ft.
Basin-fill sediments are subdivided into the upper basin-fill (the top 2600 feet) and the lower basin-fill (from 2600 feet to the basin floor). The latter, comprising permeable gravel, sand, silt, and impermeable clay, gypsum and limestone, is the primary target zone for CO2 sequestration.
The Basin and Range tectonic and physiographic province of southern and western Arizona contains over 80 basins filled mostly with sand and gravel. The Safford – San Simon basin is the largest. According to Jon Spencer, AZGS senior geologist, “This new study was done to evaluate the potential to dispose of carbon dioxide deep beneath the surface in this basin.”

Suitability of the Safford Basin for CO2 sequestration remains unclear. According to Gootee, additional studies, including seismic-reflection profiling and deep drilling, will be necessary to adequately evaluate the basin for CO2 sequestration.

The report was carried out as part of a regional study under the auspices of WestCarb. Arizona is a member of the West Coast Regional Carbon Sequestration Partnership (WestCarb), a consortium of seven western U.S. States and one Canadian Province. WestCarb is co-funded by the U.S. Department of Energy.

The report and map plate are in PDF format and available for free download from the Arizona Geological Survey Document Repository.

Citation: Gootee, B., 2012, Geologic Evaluation of the Safford Basin for Carbon Dioxide Sequestration Potential, Arizona Geological Survey OFR-12-01.

[taken from the AZGS publication announcement]

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