A NEW DIGITAL GEOLOGIC MODEL FOR CARBON SEQUESTRATION PLANNING IN THE APPALACHIAN AND MICHIGAN BASINS

Injecting carbon dioxide (CO2) into geologic reservoirs is a promising method to mitigate anthropogenic greenhouse gases. To facilitate planning, a regional-scale, digital geological model was created. This work was conducted for a seven-state area as part of U.S. DOE-funded projects including the Midwest Regional Carbon Sequestration Partnership –(MRCSP) and the NATional CARBon Geographic Information System (GIS) project (NATCARB). The study sought to determine areas where the geology was promising for CO2 injection, and to estimate storage capacity of various geologic units. A regional stratigraphic correlation chart was developed to identify major target horizons for injection and potential seal layers. Key geologic siting criteria were high porosity and permeability, presence of a confining layer (trap), and overburden greater than 2,500 feet (to maintain CO2 in a dense, supercritical state). Structure and isopach maps were constructed using geostatistical methods based on elevations derived from ~85,000 individual oil and gas well records. A regional digital map of oil and gas fields was produced to show locations of natural geologic reservoirs and to support future enhanced oil-recovery operations. Various GIS techniques were used to assemble these data sets into planning maps and tools. Structure and isopach maps, coupled with estimates of porosity, permeability, salinity and geothermal gradient were used to estimate the CO2 capacities for various units in the region. To provide conservative estimates, it was assumed that only 10 percent of the reservoir pore volume was available for injection. Capacities for both volumetric displacement and solution were calculated. For example, the Mt. Simon Sandstone was estimated to have 217 gigatonnes of capacity volumetrically, and 8.3 gigatonnes of solution capacity. CO2 emissions in the region from fixed point sources (power plants, steel mills, etc.) are about 750 million tonnes/ year, thus the Mt Simon alone could provide 100 to 200 years of storage capacity.