Study And Application On Dcprcssurization And Injection Enhancement System For Wuqi Low-permeability Reservoir

Low permeability reservoirs are characteirzed by micro pore throats, low permeabilityand low filtration rales. Low injection and high injection pressuer arc the main problems. Aimto blockage of the residual oil droplets and ihc resistance of hydration iflm, surfactant systemand Nanometer polysilicon mateiral were studied to achieve the purpose of injection pressurereduction.For the property of WuQi oil and injection water, ultra-low interfacial tension surfactantsystems are developed, which has good solubility in injection water and can reduce interfacialtension to]03mN/m magnitude. And the active agents can change lipophilic surface tohydrophilic. The displacemenr expeirments show that “Qiyuan YC-3" can effectively improvethe oil-water relative permeability, improve the capacity of water injection and has a positiveeffect on reducing the injection pressure.According to the porosity, oil saturation, perforation thickness, oil-bearing area，watcirlood sweep efficiency, producing degree of the test block, the total injection amount of"Qiyuan YC-3" was determined. According to the fractuirng parameters, wellhead rupturepressure, hydrostatic pressure, friction and bottom hole pressure, the maximum wellheadinjection pressure was calculated, the proccss of agents injection was determined.Nano injection augmentation system mainly contains polysilicon particles with the size of】0-20nm. When the water temperature is up to80degrees, it will split into a mean patriclediameter of4.75nm debris, not plugging formation pore throat of Yanchang oilifeld. Coredisplacement expeirment shows that the MGS-W solution can incerases the water flow ratefrom0,25ml/min to0,475ml/min, increasing by90%. Nano augmented injection technologywas carried out with success rate of100%in6wclis of Wuqi oilfield.