Carbon Dioxide Storage Resource Assessment of the Mississippian and Morrowan Strata in the Anadarko Basin

The U.S. Geological Survey (USGS) is completing an assessment of the geologic storage potential for carbon dioxide (CO₂) within the Anadarko Basin. This assessment is being performed as part of the USGS national assessment of geologic CO₂ storage resources in which individual sedimentary basins are divided into storage assessment units (SAUs) based on geologic characteristics such as lithology, porosity, permeability, reservoir depth, formation water salinity, and the presence of a regional sealing formation. This study focuses on the assessments of the Mississippian Composite SAU, at depths of 3,000 to 13,000 feet, and the Mississippian Composite Deep SAU, at depths greater than 13,000 feet.

The Mississippian Composite SAU and Mississippian Composite Deep SAU are composed of the porous sand intervals of the Lower Pennsylvanian, Lower Morrow Formation and Mississippian Chesterian, Meramecian and Osagean Stage strata. The sands in the Lower Morrow Formation are coarse clastics deposited in channels that were eroded during low-stand, subaerial exposure of marine mud deposits. The Chesterian strata are composed of interbedded shales, sandstones and carbonates deposited in an environment that was transitional from early non-marine and littoral to late near-shore and shallow marine. The strata of the Meramecian and Osagean Stages are mostly limestones and dolostones deposited in a restricted shelf environment. The shallow marine, organic and silty claystones of the Upper Morrow Formation, which overlie the porous sand intervals, act as the regional sealing formation for the SAUs, and the boundary of the Mississippian Composite SAU is largely dictated by the extent of the Upper Morrow Formation in the Anadarko Basin.

The Mississippian Composite and Mississippian Composite Deep SAUs have the potential to store large volumes of CO₂ on the basis of the average porosity of net porous intervals and areal extent. Average porosity for the Mississippian Composite SAU and Mississippian Composite Deep SAU ranges from 8 to 16% and 4 to 8%, respectively. The Mississippian Composite SAU covers an area of approximately 24,600,000 acres and has an average thickness of 900 to 2,500 feet. The areal extent of the Mississippian Composite Deep SAU is defined by the 13,000 foot depth contour of the Mississippian interval and covers approximately 4,000,000 acres with an average thickness of 2,700 to 4,300 feet.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California