Experiment Study On Polymer-surfactant System Flooding Technology In An 12 Block Of Shen 84 Oilfield

In recent years, field test and industrialized application of alkaline/surfactant/polymer(ASP)flooding has carried out in oilfields such as Daqing, Shengli, Xinjiang and Liaohe, which has obtained obvious effect of increasing oil and decreasing water and good economic efficiency. But in actual application process, there have been some problems of alkaline alkaline/surfactant/polymer(ASP)flooding, which bring tremendous trouble to oilfield ordinary production and restrict the large-scale extending application of ASP flooding seriously. Alkali free polymer-surfactant compound system flooding is new technology for EOR which has attained extensive attention in recent years. Compared with ASP system, there is no alkali in SP system which can exhiait the viscoelasticity of polymer to the utmost extent, weaken corrosion and scaling phenomenon caused by alkali, of which flooding effect is close to ASP flooding with ultrolow interfacial tension at the same time, and can enhance the environmental protection property of chemical displatement agents. Therefore, SP system flooding has become the new direction of tertiary recovery. Acooding to practical demand of oilfield, combined with geologic feature and fluid property, the author screened the polymer and surfactant needed by SP flooding of an 12 block of shen 84 oilfield, evaluated the viscosity, interfacial tension, flow property and flooding efficiency, focusing on optimizing injction parameter. The results show that polymer relative molecular weight matching with rock pore size is 500×104 to 1000×104, high molecular weight polymer is recommended to be used in SP flooding if considering the destrorying function of injecting water to rock structure. Without alkali, SP system with nonionic surfactant S-ANSUN/Daqing Zaichuang and polymer can form ultrolow interfacial tension with crude oil. The type of displatement agent, injection time, slug size and compound mode can affect flooding effect, chromium can make cross-linking reaction among polymer molecule, forming polymer gel of intromolecule cross-linking, which has good compatibility with SP system, high concentration polymer flooding or chromium polymer gel and SP flooding is recommended as flooding mode for shen 84. The high concentration polymer is composed of high molecular weight polymer and injected water of shen 84 oilfield, polymer concentration is 1500mg/L to 2000mg/L, slug size is 0.57PV, chromium polymer gel is composed of high molecular weight polymer whose concentration is 2000mg/L and and chromium, in which the ratio of polymer to chromium is 180:1, SP system is composed of high molecular weight polymer whose concentration is 1000mg/L and nonionic surfactant S-ANSUN whose concentration is 2000mg/L and injected water.