Abstract: After polymer flooding in Daqing Oilfield, the dominate seepage channels were very developed in the reservoir, the three major interferences, that is interlayer interference, inner layer interference and plane interference, intensified, the consumption of high-concentration polymer for flooding grew, and the economic benefits declined. In view of these problems, PPG gel particles were developed independently, and the PPG+polymer flooding technology were established, realizing the organic combination of "plugging, adjusting and flooding". Through experimental methods such as instrument detection and physical simulation, etc., the seepage characteristics and oil displacement effect of PPG+polymer system were analyzed, and the optimal system formula and injection pattern were screened. The research results show that: PPG for flooding control can increase viscosity, and viscosity retention rate of PPG+polymer system for flooding is as high as 78.9% after 90 days. Compared with pure polymer solution, the viscoelasticity of PPG+polymer system increases significantly, and the system has stronger plugging control properties. The optimal flooding effect can be achieved by firstly injecting PPG+polymer for plugging control with 0.05 PV and then injecting PPG+polymer for flooding control with 0.70 PV, which can save polymer consumption by 24%. After implementing PPG+polymer system for flooding control to the blocks for research and prediction, the recovery rate has increased by 8.57 percentage points. The research can provide technical support for continuous and efficient development of quaternary oil recovery stage.

Key words: quaternary oil recovery, PPG+polymer system, viscoelasticity, flooding control, Daqing Oilfield