Studies On Secondary Development Technology Of Main Reservoir In Eastern Fault North First Block After Polymer Flooding

After polymer flooding in main reservoir, there is still nearly50%oil remaining in thesubsurface, and these geological reserves are high quality reserves of Daqing oilfield,distributing in the main reservoir with large-scale channel sandstone, large thickness and highpermeability. In order to effectively develop these reserves, there is an urgent need to explorefurther enhanced oil recovery technology after polymer flooding in main reservoir, to providetechnical support for the sustainable production in Daqing oilfield.Through the laboratory study on viscosity stability, viscosifying action, emulsification,wettability and flooding effect evaluation of polymer surfactant, it is determined that polymersurfactant flooding is feasible; through the field test study on the distribution of the residualoil in main reservoir after polymer flooding, by studying suitable injection-production spacing,reasonable injection parameters, injection-production dynamic changes and effectcharacteristics of polymer surfactant flooding in main reservoir after polymer flooding, andby analyzing displacement effect and economic benefit of polymer surfactant flooding,secondary development method in main reservoir after polymer flooding is determined.From laboratory and field tests, several conclusions can be got as follows: first, in theflooding, polymer surfactant has the characteristics of large dynamic viscosity, strongemulsification and solubilization and prominent deep profile control, these multiplecharacteristics are better than those of polymer, a large number of core flooding experimentsachieve better EOR effect; second, quality detection criterion for polymer surfactant andmethods of performance evaluation are established; third, by narrowing the well spacing andutilizing the emulsion, adsorption and plugging action of polymer surfactant, residual oil inthe upper zone of thick oil reservoir and retention area after polymer flooding can beeffectively recovered, with the oil recovery improved by8-10%; fourth, in the main reservoirafter polymer flooding, decrescendo tracking adjustment method of injection parameters forpolymer surfactant flooding is determined; fifth, production well fracturing effect isprominent, after injecting polymer surfactant, fracturing production wells with producedliquid drop by50%can promote the effect; sixth, field tests have proved that reducing wellspacing polymer surfactant flooding technology is feasible in the main reservoir after polymerflooding, production cost of tons of oil is$16.8a barrel, at the oil price of$65, with input–output ratio of1:3.86, a better economic benefit can be achieved.