强碱三元复合驱长岩心模拟实验中成垢离子变化规律

Variation patterns of precipitable ions during the process of alkaline/surfactant/polymer flooding upon the long core

利用强碱三元复合驱替液对长岩心进行驱替实验,根据驱替液中离子质量浓度及岩心中元素质量浓度变化结果,分析三元复合驱过程中成垢离子的变化规律,讨论强碱三元复合驱替液与岩心矿物的物质交换和化学反应对成垢离子变化规律的影响.结果表明:在碱性条件下,驱替液中Ca2+、Mg2+的质量浓度迅速降低至2.000×10-3mg/L以下,岩心中的Ca2+、Mg2+再次经历溶出和沉淀的过程;驱替液中Si4+的质量浓度经历迅速上升和稳中有降过程;随着驱替过程的不断进行,驱替液中的OH-质量浓度逐渐增加,直至达到饱和值.

By flooding the long core with alkaline/surfactant/polymer,together with measuring the ions in flooding fluid and concentration of the corresponding elements in the core,the variation of precipitable ions during the process of alkaline/surfactant/polymer flooding is studied and the effect of material exchange and chemical reaction between alkaline/surfactant/polymer fluid and the mineral in the core upon the variation of precipitable ions during the process of alkaline/surfactant/polymer flooding is discussed It has been found that in the presence of alkali the ions of calcium and magnesium in flooding fluid decreases to almost trace concentration.However,the element of calcium and magnesium in the core may still experience the process of salvation and sedimentation.On the other hand,the element of silicon in the flooding fluid increases swiftly and then keeps constant or decreases a little during the flooding.In contrast,the concentration of hydroxide ion in flooding fluid increases gradually but continually until the hydroxide ion becomes saturated.