Carbon Storage Potential in the Southern Illinois Basin: Preliminary Results of the Kyccs Test Well, Hancock County, Kentucky
The Kentucky Consortium for Carbon Storage, co-funded by the Commonwealth of Kentucky and industry through the Western Kentucky Carbon Storage Foundation, is testing geologic CO2 storage potential of the southern Illinois Basin. Identification of commercial-scale carbon storage targets in the deeper part of the basin is challenging because this area lacks a thick, uniform porous reservoir zone. The Upper Cambrian Mount Simon Sandstone has significant CO2 storage potential in Illinois, Indiana, and parts of Michigan and Ohio, but in western Kentucky it is thin and deeply buried, with poor reservoir quality at depths greater than 8,000 ft. Other clastic reservoirs, such as the Ordovician St. Peter Sandstone, are thin and lack regional continuity, but may be viable targets in some areas. KYCCS is focusing its efforts on the CO2 storage potential of an approximately 4,000 ft thick carbonate sequence, the Cambrian-Ordovician Knox Group. Knox dolostones are heterogeneous, containing porous zones up to 50 ft thick, separated by impermeable dolostone confining layers. Porosity ranges from solution vugs to intercrystalline pores, with a variable fracture component.
KYCCS will drill and evaluate an 8,300 ft research well in Hancock County in the spring of 2009. Data from this well will characterize the St. Peter, Knox, and Mount Simon at this location, and test their CO2 injection capacity. Previous waste-disposal and gas-storage wells indicate good injectivity and containment in the Knox at depths of 3,000 to 6,400 ft, including a site where 4,000 tons of supercritical CO2 accumulated after acid dissolution of dolostone. Extensive cores and geophysical logs will be taken to characterize both the reservoir zones and the confining layers in the well. Geophysical characterization includes 26 miles of new 2-D seismic data that will be integrated with geologic data obtained from the well. Injection tests using brine and CO2 will be conducted in the open hole, using straddle packer assemblies. Modeling the fate of injected CO2 in the Knox will be difficult because of the complex nature of the carbonate pore system.
If the Hancock County test shows the Knox to be a viable sequestration target in the southern Illinois Basin, further evaluation will be justified. The Knox occurs at depths suitable for supercritical CO2 injection in the Illinois and Appalachian Basins, and comparable strata are present in west Texas (Ellenberger), and Kansas and Oklahoma (Arbuckle).
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009