Sensitivity Analysis on Effective Parameters on Water Alternative Gas (WAG) Flooding for Enhanced Oil Recovery (EOR)

Enhanced oil recovery (EOR) methods are employed for increasing oil recovery after natural production of the reservoir. Each EOR process has limitation for applying in reservoirs due to rock and fluid condition. In water alternating gas (WAG) flooding, many parameters such as reservoir thickness, horizontal permeability, connate water saturation effect on oil recovery factor. In this study, main parameters that effect on WAG oil recovery were discussed using fraction factorial design and simulation. The CMG-GEM was used for simulation study. The Minitab statistical experimental design software was used for stochastic analysis. The results show reservoir thickness, connate water saturation, and the interaction of two parameters reservoir dip angle and horizontal permeability had main effect on oil recovery factor. Finally, a regression model based on the effective parameters was obtained. This regression model can be used to estimate the oil recovery during WAG flooding. According to the results of this study, the performance of WAG process in different candidate reservoirs can be predicted and one can rank the reservoirs to select the one with maximum recovery factor for further detailed reservoir and pilot studies.