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蒙脱石作为常见的粘土矿物,广泛存在于含油气盆地中。针对由于蒙脱石具有强烈亲水性,遇水体积可膨胀至原体积的数倍甚至数十倍,从而造成油气储层的水敏损害这一实际问题,对蒙脱石在强碱条件下发生结构变化与物相转变,实现降低其亲水性进行了详细的实验研究。探讨了天然钙基蒙脱石与天然钠基蒙脱石在80℃,1 mol/L KOH溶液中所发生的相变过程;通过XRD、SEM、TEM等测试手段分析查明其碱溶相变最终产物主要是微米级纤维状、柱状、颗粒状的菱沸石和麦钾沸石,均为不具膨胀性的架状硅酸盐矿物;最后通过自由膨胀实验证实蒙脱石碱溶产物膨胀性较原矿物显著降低。研究成果为转化油气盆地中“水敏性”粘土矿物,降低油气储层水敏损害,保护储层与提高采收率,提供了新的思路。
Montmorillonite, as a common clay mineral, is widely found in petroliferous basins. In view of the fact that montmorillonite has a strong hydrophilicity, the volume of water can be expanded to several times or even tens of times of the original volume, resulting in water damage of oil and gas reservoirs. Structural changes and phase transition occurred, to reduce the hydrophilicity of a detailed experimental study. The phase transitions of natural calcium-based montmorillonite and natural sodium montmorillonite in 1 mol / L KOH solution at 80 ℃ were investigated. The results of XRD, SEM and TEM analysis showed that the alkali-solution phase transition The final product is mainly micron-sized fibrous, columnar, granular chabazite and kojite zeolites, are non-swelling shelf silicate minerals; Finally, by free-swelling experiments confirmed that the expansion of montmorillonite alkalinity than the original Minerals decreased significantly. The research results provide a new idea for transforming “water-sensitive” clay minerals in oil and gas reservoirs, reducing water damage, reservoirs and enhancing oil recovery.