Study on the Dual-compound Flooding System in Daqing Oil Field

ORS and ampho-surfactant M were ascertained as flooding agent for Xingbei Oilfield in Daqing by screening experiments.The effect of concentration of the surfactant,the concentration of sodium phosphate used as sacrifice agent,the concentration of the polymer on flooding system activity and viscosity,were investigated,as a result,the SP(sarfactant-polymey) binary flooding system suited for the Xingbei oilfield was obtained.In addition,indoor physical modeling experiments and field application tests were conducted.The results showed that the interfacial tension between SP or ASP(alkali-surfactant-polymer) system and crude oil decreased in the beginning,and then increased slowly with the increase of the concentration of the surfactant,and could reach up to 10-3 ultra-low magnititude.When the phosphate concentration changed from 0 g/L to 6 g/L,with the concentration increasing,the viscosity of the flooding system reduced slightly,and the interfacial tension decreased first and increased slowly afterward,reaching the lowest at the concentration of 2 g/L,the viscosity increased with the increase of the polymer concentration.The viscosity of SP system was obviously higher than that of the ASP system at the same polymer concentration.Flooding experiment results showed that as for the displacement effect,the SP flooding system was better than the ASP system;weak alkali ASP system was better than the strong alkali ASP;the system with sacrificial reagent was similar with that without sacrifice agent,however,the former could reduce 30%～50% of the surfactant by weight.The results of field application tests showed that the pump checking period of production well flooded with SP system was longer than that with ASP system,resulting in saving the cost.