CO₂ EOR Plays and Geologic Controls on CO₂ Sequestration in the Gulf Coast and Permian Basin

William A. Ambrose, Mark H. Holtz, and Vanessa Núñez López, Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX

The Gulf Coast and Permian Basin contain a wide variety of oil plays having potential for enhanced oil recovery (EOR) from injection and miscible displacement of CO₂. Many of these plays are regional and extend beyond state borders. Oligocene, Eocene, and Miocene oil plays extend from central Louisiana to South Texas, whereas the geologically older Travis Peak–Hosston and the Cotton Valley–Smackover oil plays collectively extend from western Florida to East Texas. The Permian Basin in west Texas and southeastern New Mexico contains a substantial number of candidate reservoirs for CO₂ EOR. The miscible CO₂ EOR oil-resource potential of these plays is enormous. For example, the total Gulf Coast potential, including Mississippi, Louisiana, and Alabama, is >4.5 billion stock tank barrels (BSTB). There are numerous opportunities for locating CO₂ injection wells either in fields for EOR or in stacked brine aquifers near potential FutureGen sites, where a near-zero emission facility would generate primarily hydrogen and CO₂ as products. The estimated current volume of storage in the EOR candidates is >2,500 million metric tons (MMT) of CO₂. The potential for CO₂ injectivity, storage, and EOR is controlled partly by structural and stratigraphic heterogeneity. The capacity for sequestration of CO₂ can be enhanced in heterogeneous reservoirs because of longer flow paths and increased interaction of CO₂ with a larger fraction of the rock volume, although this capacity can be offset by lower effective porosity owing to multiple shaly interbeds.