An Integrated Seal Analysis for CO2 Sequestration in the Patterson Field at Southwest Kansas

Carbon capture, unitization, and storage (CCUS) can play a critical role in offsetting greenhouse gas emissions in a manner of safe, economical, and acceptable to the public. There are multiple geologic complexes in southwest Kansas that could serve as potential commercial-scale carbon storage sites. Recent studies suggested more than 50 million tonnes of CO₂ storage potential are existing in a set of stacked saline aquifer reservoirs in the Patterson Field, including the Cambrian-Ordovician Arbuckle, Ordovician Viola, and Mississippian Osage. They are sealed by continuous shale or tight limestone of the Simpson units, Kinderhook, and Meramec-Cherokee, respectively. This research is part of an effort to understand the geological setting for future commercial CCUS projects and is funded through DOE CarbonSAFE program.

An ideal CO₂ storage site should have little or no risk of gas migration beyond the boundaries of the storage complex. We present an integrated study that combines cap rock, structural, and reservoir geomechanic analyses to ensure the seal integrity, thus maximum the storage permanence in CCUS projects. Geological and geophysical models of the storage complex are updated with the new appraisal wells and 3D seismic survey in the field to avoid any poorly cemented formation and fractured zone that could form conduit migration pathway. Reservoir geomechanical study are performed by combining the stress analysis, rock mechanical laboratory test, and numerical modeling to establish sealing properties and the maximum injection pressure during the sequestration. Preliminary results showing that the Morrow shale forms the topseal for the upper Morrow oil accumulation and also is the principal confining unit for CO₂ storage. Numerous shale units in the Atoka and Cherokee Groups provide secondary confining units that help ensure the containment of injected CO₂. The candidate reservoirs are covered by competent caprocks that arrest the fracture propagation from injection.