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在注水开发晚期的水淹油层中,其残余油量最高可达50%以上。为提高残余油采收率,本文介绍了3种化学处理法: (1)碱—酸法。它是向油层顺序注入NaOH、Na_2CO_3、原油隔离液、HCl。其作用原理其一是利用生成的钙、镁氢氧化物沉淀堵塞油层。其二是生成的石油酸钠可分散溶解油流孔道壁上的蜡质、胶质和沥青质,疏通油流孔道,降低油水界面张力。其三是生成的CO_2气在水层中与表面活性剂生成稳定的泡沫,可起选堵作用;由于生成CO_2气时,能产生很高的压力,可起微型压裂的作用。(2)碱—水泥—酸法。此工艺是碱—酸法的改进。是在挤入酸碱的同时,挤入水泥类堵剂。(3)封堵—酸化法。是由封堵出水高渗透层和酸化低渗透层两个步骤组成。封堵系用轮胎厂的橡胶残渣作堵水材料。酸化时可用盐酸或土酸。文内还分别介绍了以上方法的现场试验结果。
In flooding late development of water-flooded reservoirs, the residual oil up to 50% or more. In order to improve the residual oil recovery, this article describes three kinds of chemical treatment: (1) alkali-acid method. It is sequentially injected into the reservoir NaOH, Na_2CO_3, crude oil isolation liquid, HCl. One of its principles of action is to use the generated calcium and magnesium hydroxide precipitates plug the reservoir. The second is the formation of sodium oil can disperse the oil flow pore wall wax, gum and asphaltene, to clear the oil flow channel, reducing the oil-water interfacial tension. The third is the formation of CO_2 gas in the water layer and surfactant to generate a stable foam, can play a role in blocking; due to the generation of CO_2 gas, can produce high pressure, can play the role of micro-fracturing. (2) alkali-cement-acid method. This process is an improvement of the base-acid method. Is squeezed into the same time, into the cement plugging agent. (3) blocking - acidification method. It is composed of two steps of plugging the high permeation layer and acidizing low permeation layer. Tailor-made rubber tire blockage for water-blocking materials. Acidification can be hydrochloric acid or earth acid. The article also introduced the above method of field test results.