Simulation Study on Polymer Flooding for Enhanced Oil Recovery: A Case Study

Primary and secondary recovery methods do not give the maximum oil recovery in certain oil fields, and have a high water cut. Enhanced oil recovery (EOR) methods can solve these issues. Polymer flooding that falls under chemical EOR is one of these methods. The mechanisms of polymer flooding leads to increasing the viscosity of the displacing fluid, water, and reduces the mobility to be lower than the displaced fluid, oil. This gives a better sweeping efficiency, which translates into higher oil recovery and lower water cut because of the delay of viscous fingering and water breakthrough. To select a suitable polymer for a particular field, parameters such as; polymer viscosity, concentration, slug size should be studied carefully. The aim of this study is to evaluate the polymer injection process, and to design an optimum polymer flooding scenario regarding improving the oil recovery factor and net present value (NPV) for X-oilfield in Iraq. The workflow of this study starts with building a reservoir model using Petrel software that fits a cited screening criteria. Then, designing a base case of a secondary recovery method of water flooding using Tnavigator software. After that, implementing a polymer sensitivity analysis, where scenarios with different concentration, viscosity, injectivity, slug size, and shear thinning are created. Finally, choosing a best-case scenario that represents the optimum oil recovery and NPV. The results of this study show that when polymer flooding was implemented compared to water flooding, with a concentration of 5000 ppm, viscosity of 8.5 cP, and slug size of 37.5% pore volume (PV), the oil recovery factor increased from 44.67% to 63.73%, and the NPV was increased from $9.6 billion dollars to $13.1 billion dollars. The results comply with the findings of several researchers.