An improved study of near-well zone flooding for polymer solution through the mechanical shearing and forchheimer flow simulation

Abstract

Polymer flooding is a vital tertiary oil recovery technology that maintains stable oilfield production during high water cut periods. This technique involves improving the viscosity of injection fluids by using polymer solutions, which help reduce the mobility ratio of oil and water, expand sweep efficiency, and increase swept area. However, highly viscous polymer solutions form complex spatial structures between and within molecules, which leads to significant viscosity loss rates in the near-wellbore region at the well injection end. To address this issue, a near-wellbore shear device with nozzle completion was built to study the shear effects of two types of polymers. The study revealed that the polymer solutions destroyed intermolecular and intramolecular structures after shearing, causing the water cut curves to shift up and left. Based on the Brinkman equation of COMSOL Multiphysics's Carreau model, the percolation model of polymer solution in the near-well zone was constructed. COMSOL simulation results also demonstrated that high-speed shearing at the nozzle orifice was the primary cause of shear degradation. Therefore, it is essential to adopt reasonable injection intensities and proper polymer solution concentrations in oilfields to maximize oil recovery and minimize production costs. This is of crucial engineering significance in guiding oilfield production and optimizing injection parameters and processes.