Study On Surfactant System For Binary Composite Flooding In GX Area

Considering the problems of unclear formula evaluation index and low efficiency of formula design,this paper took GX oil reservoir as background,GX crude oil as research object,the appearance of ultra-low interfacial tension and phase behavior as index,finally optimized efficient flooding systems in the GX area and established a preferred method for formulating SP(surfactant/polymer)binary composite flooding system and clarified factors affecting oil recovery.Based on the hydrophobic association polymer APP7 used in the GX region,selected surfactant which has good compatibility with APP7 by viscosity experiment,and discuss the mechanism of the result.Then,took a large number of surfactants(anionic,nonionic and long-chain amide betaine)and their complex systems with GX crude oil in phase behavior experiment,constructed the ultra-low interfacial tension experiment,constructed the ultra-low interfacial tension compound system in GX reservoir.After which,carried out phase behavior experiments and selected 13 different kinds of compounding ratio surfactant systems,and finally the compounding system which could be used in GX formation conditions was erucamide betaine/KPS(combination ratio 3:1),6501/palmitic amide betaine(complex ratio3:1)and oleic acid amide betaine/KPS(1:2).The optimum salinity of which were 1.0wt%,2.0wt% and 1.0wt% respectively.Then calculated the oil displacement efficiency by the oil displacement experiment and verified the experimental results.Finally,constructed a method for chemical flooding surfactant system,and confirmed oil displacement systems with low interfacial tension,large medium phase volume and good oil displacement effect for GX area.Experiments showed that for GX regions,dynamic interfacial tension is not the only criterion that determines ultimate recovery.In addition to the dynamic interfacial tension,phase experiments and physical simulation of oil displacement experiments are required to use to achieve higher oil recovery.The oil displacement system obtained by the phase experiment is more consistent with the experimental results of the oil displacement efficiency.