Improving oil recovery using double displacement process

Abstract

Most oil reservoirs have low recovery efficiency when they are produced by natural energy. Iinjection of water to displace oil may be implemented as secondary recovery. The oil recovered by secondary process is around 40-60% depending on oil and reservoir properties. At the end of waterflooding, there is still a lot of water evaded oil left in the reservoir. Then, an stage of oil recovery such as double displacement process should be considered. In this study, double displacement process (DDP) is applied to dipping reservoir to investigate effect of various parameters such as dip angle, location of injector, water cut ratio in order to optimize oil production with this process. Sensitivity analysis is performed to determine the effect of various three-phase relative permeability correlations and difference in residual oil saturation in presence of water on oil recovery. The results from reservoir simulation indicate that DDP greatly increases the oil recovery factor on top of waterflooding. However, there is very small difference in oil recovery factor for different injection strategies. Nevertheless, for low degree dipping reservoir, injecting gas at the most updip location gives the shortest production time. For moderate dipping reservoir, conditional DDP gives the shortest production time. For high degree dip angle, the production times are similar for all strategies. For sensitivity cases, difference in three-phase relative permeability correlations and residual oil saturations makes almost no difference in RF but different times of production.