聚合物粘弹性及体系的界面张力对驱油效率影响的实验研究

【作者】 陈凌云；

【导师】 吴文祥；

【作者基本信息】 大庆石油学院 ， 石油工程油气田开发， 2002， 硕士

【摘要】 石油是一种不可再生的资源，更是国家经济发展的重要经济命脉。随着油田的开采，尤其是高含水开采阶段，无论是经济指标，还是技术指标，都将变差。油井含水增加，产量下降，基本建设投资增加，成本增大。如何经济有效地开采水驱开发后残留在地层中的60～70％的剩余油，已成为世界各国油藏工程专家努力攻关的课题。 碱/表面活性剂/聚合物（ASP）三元复合驱是三次采油中较为成熟一种驱油技术。该技术利用了三元体系中的碱、表面活性剂和聚合物三种化学剂的水溶液协同效应驱替原油。它可以在表面活性剂浓度很低的情况下与原油形成超低界面张力，大大地改善了驱油效率；同时，由于聚合物的加入，这种体系又具有较高的粘度，可获得有利的流度比，从而大幅度地提高原油采收率。大庆油田三元复合驱现场实践中取得了较好的效果，可以提高采收率20％左右。 ASP体系与原油接触后界面张力很快降低到10^-2mN/m以下，保持超低界面张力有利于提高洗油效率；而采收率的提高主要归功于粘度与弹性的增加。普遍认为聚合物溶液可有效提高波及效率。近来的研究指出聚驱可提高驱油效率，有人认为这是毛管数提高之故，因为采收率大小取决于于毛管数。目前在国内外已进行了大量的三元复合驱室内研究和矿场试验，但针对粘弹性条件下界面张力及粘弹性对原油采收率、残余油饱和度的影响的实验研究仍属空白。本课题通过界面张力测定，研究驱油体系的界面特性；通过体系G—弹性模量的测定，研究驱油体系的粘弹性；在尺寸为中φ2.5×10cm，kg为1000md左右的人造岩心物理模型上进行物理模拟实验，研究了体系的粘弹性和界面张力对原油采收率的影响。 本课题实验结果表明，提高聚合物的粘弹性能够有效地提高ASP体系的驱油效果；而保持超低界面张力能够提高采收率，根据此实验结果，采用适当措施找出最佳试验方案，能够有效改善驱油效果，降低成本，为实现经济有效地开采水驱剩余油做出贡献。更多还原

【Abstract】 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.更多还原