numerical simulation of co2-wag process for proper design of operating parameters

Different enhanced oil recovery (eor) methods are widely implemented to increase the efficiency of oil production from reservoirs. water-alternating-gas (wag) is one the eor methods in which both water and gas are injected into the reservoir to reduce the residual oil saturation. among different wag processes, co2-wag is one the most environmental-friendly and efficient methods in which co2 is used as the injection gas. the low minimum miscibility pressure (mmp) of co2 turns this gas to a special candidate for eor applications. in this study, impact of anisotropy coefficient and operating parameters including injection rate, pattern size and slug size on performance of this process was investigated by performing numerical simulation. generally, it was concluded that regardless of anisotropy coefficient, oil recovery factor increases as the ratio of well distance to reservoir thickness increases. moreover, high injection rates should be avoided to decrease the phase segregation as the injection slug moves toward production well. finally, it was concluded that the performance of wag process is logarithmically correlated with anisotropy coefficient and well distance to reservoir thickness.