CO2 Enhanced Gas Recovery and Geologic Sequestration in Condensate Reservoir: A Simulation Study of the Effects of Injection Pressure on Condensate Recovery from Reservoir and CO2 Storage Efficiency

Abstract

Abstract Hydrocarbon recovery efficiency can be increased by injecting miscible CO 2 gas in order to displace hydrocarbons towards producing wells. This process of enhanced oil recovery can simultaneously and subsequently be used for CO 2 storage after complete hydrocarbon reservoir depletion. Condensate reservoirs provide possible storage sites, with the additional benefit of enhanced gas recovery through re-pressurization of the reservoir and re-vaporization of the condensate. However a lot more research needs to be done. In order to accurately determine the effect of the injected CO 2 , the compositional simulator CMG- GEM was used. The aim of this paper was to examine the effect of CO 2 injection pressures on condensate recovery and CO 2 storage. We used a tuned Peng and Robinson equation of state to model the interactions of the CO 2 with the hydrocarbons. It was observed that the injection of CO 2 had a positive effect on the re-vaporization of condensate dropout in the reservoir. Increasing the injection pressure yielded higher condensate recoveries up to a certain value (as high as 16%). At this point, the producer experienced liquid loading issues. Additionally, more than 90% of the injected CO 2 remained in the reservoir for this specific model. A large percentage of this trapped CO 2 remained in the supercritical phase. Increasing the injection pressure increased the percentage of CO 2 trapped in the reservoir by hysteresis (as high as 30%). This increased injection pressure had negligible effects on the CO 2 dissolved in the formation water. The results from these simulation studies show that the use of CO 2 to increase condensate recovery from the reservoir is feasible with the additional benefit of CO 2 sequestration.