--> Regional CO<sub>2</sub> Storage Capacity Estimations for Arbuckle Saline Aquifer in South Central and Southwestern Kansas
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Regional CO2 Storage Capacity Estimations for Arbuckle Saline Aquifer in South Central and Southwestern Kansas

Abstract

The Arbuckle Group (Cambro-Ordovician) consists dominantly of shallow shelf carbonates overprinted by karstic features developed during repeated subaerial exposure. The Arbuckle saline aquifer in south-western and south-central Kansas is an ideal candidate for CO2 sequestration because of thickness (600–1000 ft), supercritical depth (>3500 ft), stratigraphic isolation from freshwater aquifers, and limited oil and gas production. In addition, this formation has an extensive history of waste and back flow water disposal in Kansas and Oklahoma. Moreover, the Arbuckle formation is noticeably underpressured which potentially allows for higher volumes of disposal fluids to be accepted without risk of overpressuring of the reservoir. Previously published estimates of CO2 sequestration capacity in the Arbuckle Group in Kansas vary between 1.1 to 8.8 billion metric tons based on static CO2 solubility in brine under in situ pressure and temperature. This work provides a more detailed and comprehensive approach to regional CO2 storage capacity estimations. A detailed geological characterization was performed where existing well log and core data was analyzed and new exploratory wells were drilled in central and western Kansas with extensive logging and coring programs. Based on this analysis, ten potential commercial-scale CO2 injection sites were selected, characterized, and modeled. Accurate calculation of CO2 storage capacity for south-central and south-western Kansas was performed where researchers used several different approaches including volumetric calculations (proposed by Department of Energy and Carbon Sequestration Leadership Form Task Force of CO2 Storage Capacity Estimation), extrapolation based on CO2 storage capacity of selected ten modeled sites, detailed regional model numerical simulation, and using statistical approach. Modeling scenarios included Previous HitmaximumNext Hit Previous HitallowableTop pressure, which was estimated based on calculated fracture pressure gradient, various pressure maintenance scenarios, and boundary conditions. Depending on the proposed scenarios and assumptions for system conditions, estimates for CO2 storage capacity for south-central and south-western Kansas vary between 0.66 to 2 billion metric tons.