SOLVING THE CARBON STORAGE PUZZLE IN KENTUCKY

Anticipating requirements to mitigate CO2 emissions from the coal use in Kentucky, and to provide incentives for the development of coal-to-synthetic fuels facilities in the commonwealth, the Kentucky legislature passed House Bill 1 in a 2007 special session. HB 1 authorized funding for three mandated research projects by the Kentucky Geological Survey: deep CO2 storage test wells in the Western and Eastern Kentucky Coal Fields and tests of CO2 enhanced oil and gas recovery (EOR/EGR) including the CO2 storage capacity of Devonian black shales. To accomplish these mandates the KGS has formed the Kentucky Consortium for Carbon Storage with industry participants. The challenge of the deep storage tests is to demonstrate CO2 storage in diverse reservoirs with a limited number of test wells. Subsurface pressure, temperature, and water salinity suggest CO2 storage in reservoirs 2500-8000 ft deep. The Cambrian Mt. Simon Sandstone is an attractive CO2 storage reservoir over much of the Midwest, but its limited geographic extent, depth, and uncertain reservoir properties due to its diagenetic history may limit its utility for CO2 storage in Kentucky. Cambrian sandstones in the Conasauga Group and Rome Formation in the Rome Trough of eastern Kentucky have excellent reservoir properties but were deposited in fault-bounded grabens. The sealing integrity of these faults is not well known and needs further research before the CO2 storage potential of these deep sandstone reservoirs can be assessed. Waste injection wells in Kentucky are completed in the thick Cambrian-Ordovician Knox Group carbonates, where favorable reservoirs may be found at shallower depths. However, the Knox section has highly variable and laterally discontinuous porous and permeable intervals; thus these dense carbonates may serve as both reservoir and seal. Other strata in Kentucky with CO2 storage potential warranting further reservoir characterization are the Ordovician St. Peter Sandstone and High Bridge Group carbonates. Significant potential exists in Kentucky for CO2 EOR/EGR production. The consortium will demonstrate the effectiveness of CO2 in miscible and immiscible EOR projects in conventional petroleum reservoirs, and test the feasibility of using CO2 to displace methane in the organic-rich Devonian Ohio Shale in eastern Kentucky.