Numerical simulation study to understand the performance of RPM gels in water-shutoff treatments

Abstract

Disproportionate Permeability Reduction (DPR) is often used as a water-shutoff treatment in production wells when conventional solutions such as mechanical isolations are difficult to perform. Although this property has been well documented by different investigators, the performance of DPR treatments in field applications has varied between success and failure without understandable reasons. This work investigated the DPR performance in different scenarios to see when, where and at which conditions DPR treatments can give better results. Numerical simulation methods were used to simulate different scenarios happening in oil and gas fields such as five-spot pattern system and linear-system, with different number of layers, with and without crossflow. The possibility of using DPR treatment in hydraulically-fractured reservoirs was also investigated since many reports indicated that there is an increase in the water production for some oil and gas reservoirs after being hydraulically-fractured. Moreover, the physical reasoning behind the variations in the DPR performance for different scenarios has been extensively discussed.The results explored that the DPR performance was excellent in both of water-cut reduction and oil-recovery improvement when the flow regime was viscous dominated (viscous-gravity number<0.1). On the other hand, when the flow regime was gravity dominated (viscous-gravity number >10), the effective period of DPR treatment was a short-term remedy. Secondly, when the high-K layer is existed at the lower-zone of oil or gas reservoir, the reservoir would be a good candidate for the DPR treatment as compared with the reservoirs that have the high-K layer located at the upper zone. Furthermore, selecting the correct time to perform DPR treatments generally could have a significant role to mitigate water production. Finally, the dimensions of the treated fracture are the key components to get a successful DPR-treatment in the hydraulically fractured reservoirs.