Enhancing Recovery in High Salinity Oil Reservoirs through Optimized Polymer Flood

Abstract

Abstract The applications of Enhanced Oil Recovery (EOR) techniques are encouraged by the growing demand for oil. Optimizing oil production from current resources is becoming the main strategy for many oil producing companies around the world. Among EOR processes, polymer flooding is an attractive option in many reservoirs. The objective of polymer flooding is to control water mobility inside the reservoir to favor higher oil recovery. Several design parameters are critical for the success of polymer flooding applications. The salinity of formation water is one of the challenges which impose a limitation on polymer flood applicability. In Kuwait, most of oil reservoirs are high water salinity reservoirs. Therefore, improving the performance of polymer floods under high water salinity conditions may unlock these resources which can have enormous positive effects on oil reserves. One way for this improvement is to condition these reservoirs by injecting a slug of water (preflush), ahead of polymer, with specific characteristics. In this work, lab experiments were conducted in which the effects of several design parameters of polymer flooding are investigated under high water salinity conditions. Design parameters include preflush salinity, preflush viscosity and preflush slug size. The results suggest these parameters correlate differently with oil recovery factor. Introduction With the current growing demand for oil led by major energy consuming countries such as China and India, securing new oil resources is a critical challenge for the oil industry. Adding new oil reserves can be achieved by finding new discoveries or by optimizing oil production from current resources. The cost associated with the first option is significant since the new resources are expected to occur in challenging environments such as deep formations or deep water. Therefore, the need to optimize oil production from current resources through Enhanced Oil Recovery (EOR) techniques is a main strategy for many oil producers. EOR processes are generally classified as thermal, miscible, or chemical processes. Reservoir's rock and fluid properties and economics dictate the choice of which EOR process to follow. Thermal methods are mainly used in heavy oil reservoirs; whereas miscible processes are suitable for lower viscosity oils. Chemical EOR processes are used to reduce reservoir forces responsible for oil entrapment. There are different versions of chemical processes depending on the type of fluid used such as: polymer, alkaline, and surfactant.