The Illinois State Geological Survey has been evaluating Carbon Capture and Storage (CCS) options for nearly 20 years. The original research program began with the study of natural gas storage projects as an analog for geologic storage. Early thoughts were that the best sites for CCS are in saline reservoirs that are overlain by structurally-controlled oil and gas fields. Our research showed that these oil field structures did not have the capacity for commercial-scale capture. Deep saline reservoirs represent the largest component in a portfolio of geologic storage capacity for sequestered CO2; therefore, adequate evaluation of these reservoirs is of paramount importance. In the Illinois Basin, regional geologic analysis showed that the Ordovician age St. Peter Sandstone and the Cambrian age Mt. Simon Sandstone have the most capacity for commercial CCS. The Cambrian Potosi Dolomite had the storage capacity but there were concerns about adequate seals. Regional seismic reflection data integrated with the geologic well control suggest that both the St. Peter and the Mt. Simon reservoirs have limitations that increase project uncertainty. For example, in the St. Peter the areas containing potable water extended further southward into the basin than expected. In addition, faulting was much more common than originally suspected from the earlier maps. These faults may be capable of allowing CO2 to migrate to shallower horizons and could be a source for induced seismicity. From our integration of seismic reflection data with well data we observed the Mt. Simon Sandstone reservoir quality to be controlled not only by the reservoir depth, but also by Precambrian topography. Our DOE funded Carbon Storage Assurance Facility Enterprise (CarbonSAFE) projects build upon the lessons learned from previous research to begin developing a commercial storage complex capable of storing over 50 million metric tons of CO2. The Illinois Basin CCS research illustrates the importance of regional geologic analysis that is integrated with seismic reflection data.
|Published - 2019