Abstract

The Permian Basin in West Texas has seen a long history of CO₂ enhanced oil recovery (EOR). Over 65 sandstone, limestone, and dolomite reservoirs have been subject to miscible CO₂ floodings in the last 30 years. However, the experienced gain has not been extended to the much more porous and permeable clastic depositional systems of the Gulf of Mexico Coast. Proximity to possible anthropogenic CO₂ sources, enabling reduced costs and infrastructure, and the petrophysical character of these sandstones are just two of the many attributes that showcase the Gulf Coast formations as an attractive option for this type of tertiary recovery.

A large oil reservoir database was analyzed to determine the geologic distribution of CO₂ EOR potential in Gulf Coast oil reservoirs. Key factors to screen reservoirs in which miscible CO₂ displacement is feasible are minimum miscibility pressure (MMP) and cumulative oil production. Oil reservoirs that were screened out as potential candidates have the following characteristics: an initial reservoir pressure greater than the MMP, water drive or secondary recovery, cumulative production greater than 1 million stock tank barrels (MMSTB).

Analysis shows that the miscible CO₂ EOR resource potential along the Texas Gulf Coast is 2.7 billion stock tank barrels (BSTB), and the total Gulf Coast potential, including Mississippi, Louisiana, and Alabama, is 4.5 BSTB. Results of this assessment indicate that mature Gulf Coast clastic oil reservoirs are a new large potential target for CO₂ EOR when experi-