Study on the Potential of Enhanced Oil Recovery by Polymer Flooding in Low-Viscosity Sandstone Reservoirs with Extremely High Water Cut

The use of polymer flooding to further enhance oil recovery after the sandstone oil field entering the high water cut period is a relatively common method for third oil recovery. Homogeneous core flooding experiments show that there is no significant improvement for oil displacement efficiency during polymer flooding after high-speed water flooding in low-viscosity sandstone reservoirs. The improvement of oil displacement efficiency is mainly contributed by subsequent water flooding. The function of the polymer flooding is to control the microscopic water flow direction by profile control, and improve the microscopic wave efficiency of the subsequent injection water. At the same time, increasing the viscosity of the polymer has little effect on improving the sweep efficiency. Therefore, the potential for enhanced oil recovery by polymer flooding is limited after high-speed water flooding in low-viscosity sandstone reservoirs.