Assessing Carbon Sequestration Potential for “Unmineable” Coal Beds in Eastern Kentucky
Greb, S.F., Weisenfluh, G. A., and Eble, C.F.
Kentucky Geological Survey, University of Kentucky, Lexington, KY
Coal beds are possibly attractive sequestration reservoirs because they adsorb CO2 and because injected CO2 will displace in-place methane, which can be recovered as a fuel. If used for sequestration, however, the injected coal cannot be mined in the future. For carbon sequestration and coalbed methane development, it is important to identify coals that are unmineable, below drainage, and below the level of surface fractures (500 feet). Defining “unmineable” is problematic. Options include thickness or depth restrictions based on current mining technology, stratigraphic limits based on seams that are not currently mined, or areas that exclude current mining. In eastern Kentucky, the latter two would eliminate much of the coal field, because active mining is where coals are thickest. In order to demonstrate the effects of the economic and political factors that might determine which coals were truly unmineable, a second calculation was made for coals more than 1000 feet below drainage.
At 500 feet below drainage, the areas with sequestration potential are in the Eastern Kentucky Syncline and Middlesboro Syncline, in all or parts of 15 counties, with a maximum of 15 potential seams in a small part of that area. At 1000 feet, the area shrinks to 6 counties, most with less than 2 potential seams and a maximum of 8 potential seams in the deepest parts of these structures. There are no current power plants in this area, which means that its coal sequestration potential would depend on the economics of pipelines and methane recovery.