Mudstone characterization and classification at a proposed hub scale carbon sequestration complex: Kemper County, Mississippi, United States
Abstract
The Mississippi Embayment in the US gulf coast plain and adjacent continental shelf present a vast resource for anthropogenic carbon capture and sequestration (CCS) opportunities from point sources to hub scale sequestration projects and are likely to be the site of many sequestration facilities in the coming decades. The current need to sequester anthropogenic CO2 is no less than a thousand-fold of the current sequestration projects and saline reservoirs are a major target for injection operations both on and offshore. The Cretaceous and Tertiary strata within east-central Mississippi are proven to be world-class reservoirs, and have been characterized through the DOE CarbonSAFE Phase II (2017) and Phase III (2020) program and the drilling of 6 exploration wells. The drilling program and associated data led to a high-resolution stratigraphic delineation, reservoir and confinement characterization, and mudstone baffles, barriers, and seals classification of a 1.4 Gt resource within stacked reservoirs of multistory aggraded sandstone with a geometric mean permeability of 3.6 Darcy. The primary, secondary, and auxiliary reservoirs are the Paluxy Formation (Albian), Washita-Fredericksburg interval (Albian), and Lower Tuscaloosa Massive sand (Cenomanian) that internally contain mudstone baffles that are relatively thin and discontinuous through offset wells and the area of review and define reservoir heterogeneity. Thickly bedded aggraded paleosol deposits in the basal and upper Washita-Fredericksburg interval act as barriers to fluid flow and facilitate vertical plume confinement within the primary and secondary reservoirs. If fugitive CO2 is to vertically escape out of the designated reservoirs the Lower Tuscaloosa sand will act as a storage buffer while also preventing significant CO₂ impingement at the reservoirs and seal interface. The major confining unit to the sequestration complex is the Marine Tuscaloosa shale (Cenomanian) that is clay rich and interpreted to have internal clinoform bedding morphology and was deposited as part of a eustatic rise in base level. The mudstone barriers and Marine Tuscaloosa seal have an absolute permeability on the order of 10-100 nD are regionally present, laterally continuous, and have implicit confinement to prevent significant amounts of CO₂ from escaping the designated sequestration reservoirs and contaminating the USDW in the Naheola and Nanafalia Formations.
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- OSU Dissertations [11222]