A Study On Mechanism Of Enhanced Oil Recovery By Combinational Flooding In Conglomerate Reservoir

According to the alkaline/surfactant/polymer flooding test which will be performed in Kexia layer,Qizhong district of conglomerate reservoir in Xinjiang oil fields,the porous flow mechanics,adsorption,chromatographic separation of components,emulsification,effects of enhancing oil recovery and the influencing factors of ASP in this paper were conducted in conglomerate reservoir.Compared with the sandstone,the characters of conglomerate were that porous throat radius was small,the ratio of porous and throat was large,the connectivity was bad and so on.On the basis of conglomerate reservoir characters,the porous and throats model of microcosmic conglomerates was cored.An ASP flooding solution were composed of 1.2%sodium carbonate,0.3%petroleum sulfonate KPS,and 1200mg/L polymer KY2500,an surfactant/polymer flooding were made up of 0.2%petroleum sulfonate SP-927 and 1200mg/L polymer KY2500.The study on conglomerate microcosmic porous and throats model showed that surfactant/polymer flooding and ASP had a significant effect on enhancing oil recovery,and the later have a better effect than surfactant/polymer flooding,the result in hydrophilic model is better than it in oily model.The mechanism of driving residual oil after water flooding in hydrophilic model by surfactant/polymer and ASP flooding were driving small oil drip,denudation and emulsification,and the ASP flooding could drive large oil and make it transmute.In oily model the mechanism of surfactant/polymer and ASP flooding were similar,and the mechanism were that oil film bridge,denudation and emulsification.The diameter ratio of porous to throat have a significant effect on enhancing oil recovery in conglomerate reservoir.The adsorption of surfactant/polymer in conglomerate sand was larger than that of ASP flooding.The adsorption of polymer and surfactant in surfactant/polymer flooding respectively were 0.98mg/g and 7.4mg/g,and that of ASP flooding were 0.72mg/g and 7.2mg/g,the adsorption of alkali in ASP was 5.7mg/g.The emulsification study showed that the capability of emulsification in ASP was better than it in surfactant/polymer,the anterior can reach 30%,and the later was 4%with the exception of 20%in volume ratio of oil to water 7:1 and 9:1.The study on physics simulation experiment in combinational flooding showed that chromatographic separation of components in combinational flooding happened in conglomerate sand package,and that of surfactant/polymer and ASP flooding were different.The W_P-S in surfactant/polymer flooding was in the range of 0.44 and 0.58,but that of ASP flooding can reach 1.73,the surfactant in ASP flooding was lagged behind badly,so the separation of components in surfactant/polymer was less and that of ASP was worse.The effects of enhancing oil recovery were researched and the study showed that surfactant/polymer flooding can increase the oil recovery by 9.11%,and the ASP flooding can do it by 19.20%.Though there are many negative factors such as reservoir damage,serious asymmetry and asymmetrical pressure distribution in Kexia layer,Qizhong district of conglomerate reservoir,the alkaline/surfactant/polymer flooding test can have a good application in enhancing oil recovery because of high residual oil recovery, and the reservoir temperature,oil viscosity,well net are fitting and so on,and the injected water and fracture water have a well cooperation.