Co-optimization of Enhance Gas Recovery and Carbon Dioxide Storage in Natural Gas Reservoirs

With the increase of carbon dioxide concentration in the atmosphere, the quick emission reduction methods, i.e. carbon capture and storage/enhanced hydrocarbon recovery (CCS/EHR), have been introduced in recent years. While using CO2 for enhancing the recovery of oil reservoirs has been the subject of several studies in the past decades, it has not been fully studied in the gas reservoirs, mainly because of high recovery factor of gas reservoirs and mixing of the reservoir gas and CO2. In this work, the process of carbon capture and storage/enhanced gas recovery (CCS/EGR) in one of the south Iran gas reservoirs was studied. After the sensitivity analyses of different parameters with an optimum design of experiments (DOE) method the significant parameter was selected and optimized using genetic algorithm (GA) considering the net present value (NPV) as the objective function. This study shows that in addition to the production of residual reservoir gas, injecting CO2 in the gas reservoirs under optimized conditions (appropriate injection pattern and operational condition and pure CO2 injection) results in the storage of considerable amount of CO2, and thereby preventing it from being emitted in the atmosphere. Therefore, as the gas reservoir recovery and revenues of clean development mechanism (CDM) increase, the process of CCS/EGR becomes economically and environmentally profitable.