Effect of a Partial Pressure Tool on Improving the Heterogeneous Oil Recovery and Polymer Solution Microstructure

[Image: see text] To improve the oil displacement effect of polymer solutions in heterogeneous oil layers and increase the energy utilization rate, Daqing Oilfield proposes a partial pressure tool to control the polymer solution injection amount in high-permeability oil layers and increase the injection amount in low-permeability oil layers to enhance the total oil recovery. To study the effect of the partial pressure tool on enhancing oil recovery and the action mechanism of the tool on polymer molecules in high-permeability reservoirs, core displacement experiments were performed to study the effects of various factors on oil recovery. Microscopic experiments were then carried out to study the differences in molecular morphology and molecular coil size of the microscopic polymer solution before and after the action of the partial pressure tool. The experimental results show that the partial pressure tool increased the oil recovery by 4.4% and that the throttling pressure difference was directly proportional to the oil recovery. The partial pressure tool subjected the polymer solution to shear deformation and reduced the molecular coil size. When the concentration of the solution was changed, the degree of change in the molecular structure and the coil size was small, and the influence on the oil displacement effect was minimal. This experiment is of great significance for improving the energy utilization rate.