Study on Downhole Viscosity Loss Law During Polymer Solution Injection

There are more than 10000 chemical flooding injection wells in Daqing Oilfield. The viscosity of polymer solution is the key factor affecting the displacement effect. Reducing the viscosity loss in the injection process can effectively improve the displacement effect, save the amount of dry powder and reduce the development cost. In order to investigate the influence of various links in the process of polymer solution injection on the viscosity loss of polymer solution, the field simulation test of viscosity loss in the process of polymer solution injection is carried out [1]. Through the simulation test, we explore the viscosity loss of polymer solution flowing through each node and different specifications of blast holes, clarify the downhole viscosity loss in the process of polymer solution injection, and maximize the potential to reduce viscosity loss.The test results show that the viscosity loss rate in the process of polymer solution injection is about 20%, and the main nodes of polymer solution viscosity loss are downhole 1000 m injection string, downhole separate injection tools and perforating holes.The viscosity loss rate of polymer solution in the process section from the injection pump to the 1000 m downhole injection string is 10.30–12.29%, and the viscosity loss rate of polymer solution in the process section of downhole separate injection tools and perforating perforations is 7.23–9.33%. This result provides technical support for improving polymer injection process and improving polymer flooding effect.