Numerical Investigations of CO2 Storage Capacity in a U.S. Gulf Coast Reservoir Coupling CO2 EOR and CO2 Sequestration

Jong-Won Choi¹, Kyung-Won Chang², Jean-Philippe Nicot¹, and Susan Hovorka¹
¹ University of Texas at Austin, Texas 78713–8924
² University of Texas at Austin, Austin, Texas 78712–0254

Geological CO2 sequestration has emerged as a promising and immediate measure to mitigate anthropogenic CO2 emissions. Among several options, coupled CO2 enhanced oil recovery (EOR) and sequestration has many advantages. Extensive information available about subsurface formations, existence of impermeable seals which prevent upward migration of CO2 plume, and existing surface and subsurface infrastructures that can be exploited for the projects. In this paper, we investigate the impact of EOR on ultimate CO2 storage capacity of depleted reservoirs with numerical modeling techniques. We simulate a coupled CO2-EOR and sequestration process in a typical depleted oil reservoir located on the U.S. Gulf Coast. The results from the simulation are compared with those from a model in which the reservoir is used only for storage purpose, without oil production. The comparison demonstrates that EOR can indeed improve the CO2 storage capacity after oil production is stopped: with a five-spot pattern, the stored CO2 mass can be increased by 14%. During EOR period, production of preexisting hydrocarbon provides space for sequestration by replacing reservoir fluids with CO2. The results also reveal that the longer EOR period leads to the larger storage capacity. This study provides a better understanding of coupled CO2-EOR and sequestration and quantitative information for establishing a strategy to maximize CO2 storage capacity.

AAPG Search and Discovery Article #90158©2012 GCAGS and GC-SEPM 6nd Annual Convention, Austin, Texas, 21-24 October 2012