碱、表面活性剂和聚合物对储层溶蚀作用及其机理研究

Dissolution Effect of Alkali,Surfactant and Polymer on Reservoir Rock

本文开展了碱液、"碱/表面活性剂"AS二元复合体系、"碱/表面活性剂/聚合物"ASP三元复合体系对储层岩石矿物的静态溶蚀实验,考察了实验过程中液相内目标离子(Ca^(2+)、Mg^(2+)、Si^(4+)、OH^-、CO_3^(2-)、HCO_3^-和Cl^-等)浓度变化规律和岩样表面主要元素(Al和Si等)含量变化。结果表明,碱对岩样的溶蚀作用主要针对黏土矿物,对长石骨架作用较小。三元复合体系处理岩样后的液相内硅铝离子浓度增加,钙、镁离子浓度降低,岩样表面硅、铝元素含量降低。随碱浓度增加、液固比增加或处理时间延长,溶蚀作用增强,表面活性剂和聚合物可以减轻碱对岩样的溶蚀作用。处理初期溶蚀作用较强,处理60d后,液相中硅酸分子发生聚合作用,并在碱性条件下脱水生成硅垢,聚合物又促进硅胶体聚集和成垢。

The static corrosion of alkali, alkali/surfactant （AS） and alkali/surfactant/polymer （ASP） system on minerals of reservoir were carried out by detecting the content of aluminium and silicon elements on the rock surface and the concentration of Ca^2＋, Mg2＋, Si^4＋, Al^3＋, OH-, CO3^2-, HCO3-and C1- in liquid phase. The results indicated that alkali mainly corroded clay minerals instead of feldspar. The concentration of Si^4＋ and Al^3＋ increased and that of Ca^2＋ and Mg^2＋ decreased in liquid phase, while content of Si and AI of the rock surface decreased after rock specimen was soaked in the ASP solution. With the increase of alkali concentration or the ratio of liquid to solid increases or soaking time, the corrosion became serious. Surfactant and polymer could reduce the corrosion of alkali on rock minerals to some degree. At fwst, alkali corroded rock strongly; after 60 days, the molecules of silicie acid in liquid phase polymerized each other and dehydrated into silica scale with the help of alkali. Polymer promoted silicone body to aggregate and scale furtherly.