Brine Chemistry in the Appalachian and Illinois Basins of Kentucky— Implications for Geologic Carbon Sequestration
T. M. (Marty) Parris1, Donna J. Webb1, Nick Fedorchuk2, Shannon Daugherty3, and K. G. Takacs1
1Kentucky Geological Survey, 228 MMRB, Lexington, KY 40506, [email protected], [email protected], [email protected]
2College of Wooster, 1189 Beall Avenue, Wooster, OH 44691, [email protected]
3University of Waterloo, Department of Earth and Environmental Sciences, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
Theoretical studies show the potential to dissolve up to 30% of injected CO2 in formation water over a period of tens of years in sequestration projects. The dissolution is important because it removes CO2 as a separate buoyant phase that would migrate upward. The extent of dissolution is partly influenced by formation water salinity, and the relationship provided the motivation for examining brine chemistry data (480 samples) collected mostly from oil wells in the Appalachian and Illinois basins of Kentucky. Specifically, we analyzed salinity distribution with depth and stratigraphy, and the influence of salinity on CO2 solubility. The brine samples come from carbonate, clastic, and igneous-metamorphic rocks ranging in age from Precambrian to Pennsylvanian, and span elevations of 1550 to -7765 ft (sea level reference). Two distinct salinity trends are observed in each basin, with Cambrian-Ordovician samples showing salinities significantly less than those predicted by trends in Silurian and younger reservoirs. Solubility calculations confirm that lower salinities along with higher pressures at depth result in more potential for solubility trapping in the Cambrian-Ordovician reservoirs. In addition, the contrast in salinity trends between younger and older reservoirs suggests the presence of an aerially extensive seal in the upper Ordovician that separates fluid populations. The sealing interval, which likely corresponds to the Maquoketa Shale and its equivalents, is significant because the seals overlie Knox Group carbonate reservoirs, which are a main sequestration target in Kentucky.
AAPG Search and Discovery Article #90095©2009 AAPG Eastern Section Meeting, Evansville, Indiana, September 20-22, 2009