The Research On High-concentration Polymer Flooding Test In West Northern Block In Lamadian Oilfield

After 20 years research, we made a breakthrough progress in Polymer flooding. But normal polymer flooding test whose concentration is 1000mg/L shows that Enhanced oil recovery by normal polymer flooding is only 10%～12%,and the ultimate recovery factor is about 50%. Enhanced oil recovery by ASP flooding can reach to 20%. However, ASP flooding technology is not yet ripe. Therefore, to further improve the oil recovery has become the largest technology problem urgently in need of solution. So the research on High-concentration polymer flooding test in west northern block in Lamadian oilfield has been done. Concrete work is as follows:Based on the research of the influencing factors of injectability, the best time of polymer flooding injection, the compound mode of the slug injection and injection parameter, we got that injectability decline with the concentration increasing, which indicates that little core plugging has been replaced. And this core plugging is good for High-concentration polymer flooding. Because of water flooding, the formation pore was enlarged. The core plugging is beneficial to improve the mobility ratio and to increase the swept volume. According to the result of the laboratory result, By plugging removal technology using of surfactant, we can increase the relative permeability of polymer solution to keep High-concentration polymer injection continuous and steady; The earlier we inject High-concentration polymer, the higher the recovery ratio increases; The more we inject High-concentration polymer, the higher the recovery ratio increases, and the best proportion is between 0.8PV and 1.0PV. The adoption of different slug injection pattern can increase the mobility ratio. And thereby we can realize the target of improved recovery.Field Test of The research on High-concentration polymer flooding test in west northern block in Lamadian oilfield shows that: Injecting High-concentration polymer in the Middle-Later Period of normal polymer flooding, can also reduce the rate of water cut increase, slow down the decline of oil production, and increase the utilization degree of reservoir; In the central area High-concentration polymer flooding enhanced oil recovery more than 20%, and the ultimate recovery factor can be up to 60%.