Laboratory Experiment Study On Chemical Flooding After Polymer Flooding In Inhomogeneous And Thick Oil Reservoir

At present, there is a tremendous potential of remaining oil in the domestic heterogeneous heavy oil reservoir. After polymer flooding, there is still more than 30% remaining oil in the main reservoir of Sazhong development area in Daqing oilfield and there is a great potential to improve oil recovery. Heterogeneity thick reservoir of offshore heavy oil oilfields are mostly in the experimental stage of polymer flooding. It is urgently needed to develop rapidly after polymer flooding. This paper optimizes chemical flooding system respectively suitable for Daqing oilfield and offshore field based on the reservoir conditions and development needs. Under the reservoir conditions of Daing oilfield, the polymer with medium molecular weight is chosen for the comparison, two kinds of polymer-surfactant agent system and a kind of binary system are optimized, and a kind of salt and shear resistance polymer system and a binary system were selected for offshore oilfield. According to the optimized system, the displacement experiment within micro lithography glass was proceeded. In this paper, the micro displacement mechanism of the 4 kinds of polymer surfactant and a kind binary system were compared and studied. As for the class I reservoir in Daqing oilfield, the injecting concentration and slug size of polymer-surfactant agent were optimized. As for offshore oilfield, according to the reservoir test, the relationship between capillary number and displacement efficiency was got, according to which the injecting concentration of binary system was optimized. In this paper, the geological characteristics and status of exploitation of typical onshore and offshore oilfields were selected, according to which the necessity of chemical flooding was demonstrated and the injection concentration was optimized. According to the characteristics of the onshore and offshore oil block, based on similarity criteria, the corresponding physical model is designed, in view of the Daqing heavy oil reservoir, the physical model of four heterogeneous thickened layers was prepared, and the displacement experiments were proceeded to research the reservoir mainstream line displacement condition, the results showed that, respectively injecting 1.05PV polymer-surfactant agent of Huading I type and Haibo type BI type after polymer flooding, the oil recovery can be improved 19.01% and 15.94% respectively, and can be improved 12.53% for injection binary system after polymer flooding. For the typical block of offshore oil based on similar criteria design three layers of heteroge neous unequal thickness physical model and to do the physical simulation experiment, the results showed that after polymer flooding injected into the 0.3PV binary system for subsequent water flooding can improve 31.48%.This paper studies the factors of the oil saturation by the electrode method and based on the problem of incomplete data obtained by the steady state test method of oil saturation given the solution, which adopted the unsaturated oil steady state method and the limit displacement method, the new method can accurately obtain the resistance-oil saturation standard curve. This paper developed drive real-time monitoring system for the oil saturation, can generate real oil saturation distribution in real time.In this paper, in view of the typical block onshore and offshore were respectively designed inter layer commingled injection production in two-dimensional parallel model to study enhance oil recovery with plane sweep in reservoir, the results show that, according to the reservoir under the condition of Daqing polymer injection 1.05PV Haibo polymer surfactant agent can improve 10.88%. Injection of 1.05PV Huading polymer surfactant experiments show:polymer surfactant agent can improve 13.69%. Aiming at the three layer heterogeneity of unequal thickness typical block in Suizhong simulation experiments show that:Polymer flooding after the injection of 0.3PV binary after polymer flooding can improve the 19.3%.This paper designed injection polymer surfactant agent after polymer flooding test scheme for typical onshore blocks, designed injection binary after polymer flooding field test scheme for typical offshore blocks.