Numerical simulation of relative permeability modifier effect on oil and water production

Excess water production is one of the most prevalent operational problems that oil companies are facing. Polymers and polymer gels have been used widely to control excess water production for mature oilfields. It is well known that polymers/gels can reduce the permeability to water (Krw) much more than that to oil (Kro). This phenomenon is called disproportionate permeability reduction (DPR) and the polymers or gels that exhibit this behavior are called relative permeability modifier (RPM). When RPMs are placed in reservoir, reduced permeability to water can lead to decreased water production, and sometimes increased hydrocarbon production, therefore prolonging the useful life of the reservoir. However, arguments exist about where and when RPM can be used. Numerical simulation was run to investigate whether RPM can be used to reduce water production and increase oil recovery for two reservoir models: one layer homogeneous formation, two-layer heterogeneous formation with crossflow. Linear flow and five-spot well patterns were considered for the simulation. Results showed that the relative permeability modification with five spot and two layers flow pattern is more effective than linear flow with two layers and one layer. The effective period of DPR treatment is longer if treated in low water cut than in high water cut. DPR can improve oil production and reduce water production during the effective period of a treatment but the final recovery could not be significantly improved even sometimes worse. Results also show that better water control results can be achieved with more gel injection --Abstract, page ii