Insights Into Oil Bank Propagation in Reservoirs Under Bottom Aquifer Drive During Polymer Flooding

Abstract

Abstract The current work aims to understand and characterise the parameters governing the development of the oil bank and its propagation in viscous oil reservoirs under bottom aquifer drive during polymer flooding. The interest in the scope originated from two recent polymer trials which culminated in different results in terms of the oil bank breakthrough time. A two-dimensional numerical model, homogeneous and anisotropic medium under the influence of gravity, is deployed. The model, subjected to an infinite Carter-Tracy type bottom aquifer uses trial's data. Various parameters were studied and compared, including remaining oil saturation, injector-producer distance, voidage replacement ratio, and polymer viscosity. The polymer trials, namely E6 and E157 gave breakthrough time within a few months and a few years respectively. Based on our study, it was concluded that the primary factor for delaying the oil gain in E157 was the remaining oil saturation. The findings address how the initial remaining oil saturation, if overlooked, could significantly delay the oil gain. Nevertheless, the injector-producer distance is another factor that could also contribute to such a delay. The work outcome should be taken as a learning when developing mature oil reservoirs with similar engineering and geological settings.