Process Modeling of Co, Injection into Natural Gas Reservoirs for Carbon Sequestration and Enhanced Gas Recovery

Injection of CO, into depleted natural gas reservoirs offers the potential to sequester carbon while simultaneously enhancing CH, recovey. Enhanced CH, recovery can partially offset the costs of CO, injection. With the goal of analyzing the feasibility of carbon sequestration with enhanced gas recovery (CSEGR), we are investigating the physical processes associated with injecting CO, into natural gas reservoirs. The properties of natural gas reservoirs and CO, and CH, appear to favor CSEGR. In order to simulate the processes of CSEGR in detail, a module for the TOUGH2 reservoir simulator that includes water, brine, CO,, tracer, and CH, in nonisothermal conditions has been developed. Simulations based on the Rio Vista Gas Field in the Central Valley of California are used to test the feasibility of CSEGR using CO, separated from flue gas generated by the 680 MW Antioch gas-fired power plant. Model results show that CO, injection allows additional methane to be produced during or after CO, injection.