Potential of carbon dioxide miscible injections into the H-26 reservoir

In order to determine the potential for CO2 injection in the H-26 reservoir, the gas-liquid phase behavior and gas-oil minimum miscibility pressure (MMP) should be tested. In this study, PVT experiments were conducted with crude oil samples from the H-26 reservoir, and the corresponding oil properties were regressed through the equation of state (EoS). Two sets of EoS parameters (EoS-5 and EoS-15) were used to determine the CO2-oil MMP. The results show that the cell-to-cell method is a convenient and accurate method to determine the MMP and verify that the H-26 reservoir can achieve miscible CO2 flooding. In addition, a case study of a typical water flooded well group was performed with a compositional model. In this case study, the characteristics of the reservoir oil component composition were found to change after water flooding, and the impacts of these changes on the CO2-oil MMP were investigated. The recovery factor of CO2 flooding was found to be 8.5% greater than that in the water-flooding scenario. This work can be used as a reference for reservoirs facing similar problems related to high water cut or low recovery.