Analysis of Devonian Black Shales in Kentucky for Potential Carbon Dioxide Sequestration and Enhanced Natural Gas Production

Increased emissions of CO2, especially from the combustion of fossil fuels, are being linked to global climate change and are of considerable global concern. These concerns are driving initiatives to develop carbon management technologies, including geologic sequestration of CO2. One option for sequestration may be Devonian black shales, organic-rich rocks that serve as both the source and trap for natural gas. Most of the natural gas is adsorbed on clay and kerogen surfaces, very similar to the way methane is stored within coal beds. It has been demonstrated in gassy coals that, on average, CO2 is preferentially adsorbed, displacing methane at a ratio of two for one. Black shales may similarly desorb methane in the presence of adsorbing CO2. If this is the case, black shales may be an excellent sink for CO2 and have the added benefit of serving to enhance natural-gas production. This project will investigate the untested concept that black, organic-rich Devonian shales, like coals, could serve as significant geologic sinks for CO2. At the same time, the efficiency of stimulated production of displaced natural gas will be tested. Drill cuttings and cores will be selected from the Kentucky Geological Survey Well Sample and Core Library. CO2 adsorption analyses will be performed in order to determine the gas-storage potential of the shale and to identify shale facies with the most sequestration potential. During the second year, new drill cuttings and core samples will be acquired to investigate specific black-shale facies and their uptake of methane and its resultant displacement by CO2. Petrographic, CO2 adsorption, and methane-displacement data will be compiled and made available through professional presentations, Web-based applications, and publications.