Technical Indicators And Evaluation Methods Of Surfactant In Polymer-surfactant Flooding System

With the progress of exploration, Shengli oil field has turned into high-water period. ASP flooding is another important EOR technology after polymer flooding. Field application indicates that ASP flooding can enhance oil recovery over 20%, but many problems follows. Among of them, the most severe effect on formation is that alkaline can lower formation permeability because it can disperse formation clay and make them move and swell. Alkali scale forms after it reacts with formation fluid and rock, which does harm to formation. At the same time, alkali scale forms in the oil well to reduce the production, shortens period of checking pump etc. Alkali makes it difficult to demulsify for production fluid and can lower largely viscoelasticity of polymer. Future researches focus on surfactant-polymer flooding technology.In this paper, interfacial tension, viscosity performance anti-calcium of binary system of polymer-surfactant system that mixes surfactant with polymer are evaluated. interfacial tension and viscosity before and after static adsorption and the thermal stability of surfactants and polymer and capacity of oil wash of surfactant are also evaluated.Experiment results indicate that interfacial tension of the polymer-surfactant system and crude oil from different factories is lower than 10-3 mN/m among wide range of surfactant concentration and this polymer-surfactant system is composed of surfactant and ultra high molecular weight(UHMW) polymer. The stability of viscosity and interfacial tension is better.Studies of the polymer-surfactant system show that affected by static adsorption, viscosity of the binary system decreases, the interfacial tension between oil and water increases. Comparison of single surfactant system and binary system test data shows that the binary system before and after the static adsorption interfacial tension value is less than a single surfactant, so a single surfactant can be considered a greater impact by static single surfactant sorption.The study of the stability of the binary system, the test data show that the viscosity of the solution viscosity in the biggest drop in 7 days, 30 days, the viscosity of the system still retains more than 70%, indicating good viscosity stability of the entire system. Binary system interfacial tension values change over time gradually increased after the first showing a steady trend, 20 days after the interfacial tension stabilized, but there is still a slight increase in 30 days can be able to maintain <10-2 magnitude.