A STUDY OF GEOLOGIC CARBON SEQUESTRATION POTENTIAL IN CALIFORNIA

As part of the West Coast Regional Carbon Sequestration Partnership, the California Geological Survey (CGS) has developed a baseline study of geologic carbon sequestration potential in California. This involved identifying and characterizing porous and permeable rock formations and defining areas within the state's sedimentary basins that may be geologically suitable for carbon sequestration. Information has been compiled in digital and GIS formats to facilitate use by other members of the partnership.

The initial approach was to identify and inventory the sedimentary basins in California. Basins selected included all large or hydrocarbon-producing basins as well as other smaller basins that could be identified from the statewide geologic map of California. The resulting 104 basins were then screened to determine suitability for carbon sequestration. Initial screening criteria included the presence of significant porous and permeable strata, adequate seals, and sufficient sediment thickness to provide critical state pressures for carbon dioxide injection. Of the 104 identified basins, 28 basins met the preliminary screening criteria for additional study.

To characterize the physical rock and fluid properties of saline aquifers and hydrocarbon reservoirs, oil and gas field and reservoir data was assembled from publications of the California Division of Oil, Gas, and Geothermal Resources and other available sources. Data compiled included location, depth, field area, cumulative production, and depth to base of fresh water. In basins containing oil or gas reservoirs, physical rock and fluid properties for each reservoir unit within each field was compiled. These data included reservoir fluid, zone status, average depth, average thickness, producing area, porosity, permeability, initial pressure and temperature, formation water salinity, seal thickness, trap type, and history of secondary/tertiary recovery efforts. These data can be used to characterize reservoir/aquifer rock and fluid properties and evaluated to identify possible reservoirs for carbon sequestration. Where adequate well bore or geophysical information is available, CGS is preparing basin-wide maps showing depth to basement and gross sand distribution to identify promising areas for carbon sequestration.