The Study Of Polymer Viscoelasticity And Interfacial Tension Of The System For The Oil Displacement Efficiency In Rats

Petroleum is a kind of irreproducible resources, and it's also an important national economy vital. With the exploitation of oil reserves, especially when the water cut of reserves is high, both the economy index and technique index will get worse. The water cut of oil well increases, the production decreases, and the infrastructure investment and cost increase. How to exploit the residual oil in the stratum efficiently after water flooding, which accounts for 60~70% reserves in place, is a main task of petroleum engineering experts the entire world.ASP is a kind of mature flooding technique in EOR. It cooperates alkali, surfactant and polymer to flood oil reserves. It can produce a ultra low interfacial tension to oil with very low concentration of surfactant, and improve displacement efficiency largely; on the other hand, as a result of the addition of polymer, the system has a high viscidity, and it can get an advantageous mobility ratio, consequently it enhance producible oil index largely. ASP experiment practice in Daqing oil reserves get preferable effect, which enhanced producible oil index by about 20%.The interfacial intension of ASP system decrease down to lower than 10~~mN/m after it contact with oil, it's good to enhance displacement efficiency by holding a ultra low interfacial tension and the enhancement of producible oil index due to the increases of viscidity and elasticity. It's known to all that polymer solution can increase sweep efficiency. Recently research point that polymer flooding can enhance displacement efficiency, some researchers argue that it's due to the increase of capillary number, because researcher find that capillary number determines displacement efficiency. Presently people have made many ASP experiments in laboratory and reserves, but there are few researches about the effluences of viscoelasticity and interfacial tension on producible oil index when the system has viscoelasticity. The article investigates the effluences of viscoelasticity and interfacial tension on producible oil index: researches on the interfacial characteristics; by the determination of interfacial tension; researches the viscoelasticity of flooding system by the determination of G'(elasticity modulus)of the system; makes flooding physical simulation experiments on artificial core physical model with dimension of 4>2.5><10cm, kg=1000mdalso.The result of the task shows that we can enhance the displacement efficiency by increasing the viscoelasticity of flooding system; we can also enhance the displacement efficiency by keep a ultra low interfacial tension. If we optimize the experiment scheme in some ways, then we can improve the oil recovery efficiently, and decrease the cost, and contribute to the realization of exploitation the residual oil after water flooding cheaply and efficiently.