水包油乳液型复合泥饼清除剂的室内研究

针对裂缝性致密砂岩储层存在的高密度油基钻井液固相颗粒侵入以及泥饼难以清除等问题，开发出一种高效率、抗高温、低成本的水包油型复合泥饼清除剂。复合泥饼清除剂由混合酸、抗高温渗透剂、清洗剂、乳化剂等组成。通过对复合泥饼清除剂——水包油型乳液体系以及新型泥饼清除剂——纳米乳液体系的对比研究分析表明，在洗油方面以及溶蚀泥饼结构方面，复合泥饼清除剂效果优于纳米乳液。该复合泥饼清除剂的稳定性能强，抗温可达120℃；在静态条件下泥饼清除率可以达到90%以上，在动态条件下清除后岩心渗透率恢复值可以达到89%，最佳作业时间为8 h。在目前求降本增效的形势下，该复合泥饼清除剂剂配方简单，性能优良，解堵时间较短，能够有效改善和提高岩心渗透率恢复值。 

Laboratory Study on Oil in Water Compound Mud Cake Remover

When fractured tight sandstone reservoirs are drilled with high density oil base drilling fluids, solid particles from drilling fluids invade the formation fractures, and mud cakes are formed on the surface of the borehole wall and the surface of the fractures. The solid particles and mud cakes are diffcult to remove, causing formation damage to the reservoirs. A high effciency, high temperature and cost effective oil-in-water compound mud cake remover has recently been developed to resolve these problems. The compound mud cake remover is composed of mixed acids, high temperature penetrant, cleaning agent and emulsifer etc. Comparison of a compound mud cake remover-O/W emulsion system and a mud cake remover-nano-emulsion system showed that compound mud cake remover is better than the nano-emulsion in cleaning oil and eroding mud cakes. The compound mud cake remover has good high temperature stability; it works well at temperatures as high as 120℃. At static conditions, 90% mud cakes can be cleaned with the compound mud cake remover. At dynamic conditions, after removing mud cakes, formation permeability recovery of 89% can be reached, and the optimum treatment time is 8 h. This compound mud cake remover has simple composition and good performance, it fast removes particles and mud cakes plugging flow channels, thereby effectively enhancing permeability recovery, especially when cost-cutting and effciency-enhancing prevail presently.