The Department of Energy (DOE), including its National Energy Technology Laboratory (NETL) and West Coast Regional Carbon Sequestration Partnership (WESTCARB), established national programs to evaluate the technical feasibility of long-term subsurface geologic storage of carbon dioxide (CO2) produced by industrial activity. As part of a WESTCARB Phase III – Arizona Geological Characterization (contract No. 500-10-024), the Arizona Geological Survey (AZGS) is evaluating the potential for CO2 sequestration in permeable geologic formations that are below 800 meters (m) (2,624 feet) depth below land surface (bls). Calculating basin volume below 800 m depth is important because CO2 will only remain in a dense, near-liquid state at pressures corresponding to water overburden (hydrostatic pressure) at such depths. Successful sequestration requires both adequate permeability and porosity for large-volume CO2 injection, and an impermeable cap rock that will prevent movement of CO2 to shallower depths and potential escape to the atmosphere. Thus, research of storage potential is targeted at porous and permeable geologic formations with impermeable sealing strata in Cenozoic sedimentary basins in the Basin and Range province, and Paleozoic sedimentary formations in the Colorado Plateau province. Sediment volumes in the 88 Cenozoic basins in Arizona evaluated by Spencer (2011) total 42,247 cubic kilometers (km3), with almost half of the sediment volume in the largest ten basins. The initial screening of Cenozoic sedimentary basins with significant volume and depths (below 800 m), resulted in ten candidate basins (Spencer 2011). Part of the evaluation process is to assess CO2 storage potential and includes identifying geologic formations below 800 m depth, where groundwater salinity concentrations exceed 10,000 milligrams per liter (mg/L) of total dissolved solids (TDS). This concentration represents the threshold above which water is considered non-potable and unsuitable as drinking water (United States Environmental Protection Agency (US EPA), (US EPA 2012). This report presents the results of salinity-data collection throughout Arizona, the data sources and methods used, and a brief discussion of the results, especially with regard to areas in Arizona identified as having CO2 storage potential.Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact [email protected]
