塔里木超深复杂井钻井液工艺技术

库1井是西北石油局在山前高陡构造上完成的一口重点探井，完钻井深6941．15m。该井钻遇了砾石层和单层厚度为135m的可蠕变膏盐层，井底温度高、压力高的高压气层和高压盐水层．钻井过程中易发生渗漏、垮塌情况。该井一、二开采用聚合物钻井液；三、四、五开采用高密度聚磺钻井液，并配合了相应的钻井液维护处理措施。现场应用表明，该套钻井液体系解决了泥岩坍塌、膏盐层溶解、蠕变造成的井眼不稳定问题，保证了φ244．5mm和φ250．8mm复合套管的入井、固井的顺利进行，克服了五开井段硬脆性泥页岩剥蚀掉块的危害，井底高温对钻井液性能的影响，解决了超深井段低排量的悬浮携岩问题，较好地保护了油气层

Drilling fluid technology for the ultra-deep complex wells in Tarim

Well Ku-1 is an important exploration well drilled in Shanqian structure, with a drilled depth of 6941. 15 m. This well drilled through the gravel layer, creeping gypsum salt bed of 135 m, and HTHP gas zone and high-pressured saltwater zone, lost circulations and hole collapses were frequently encountered during drilling. Polymer drilling fluid was used in the 1st and 2nd section of the well, and high-density polysulfonated drilling fluid was used in the 3rd, 4th, and 5th section, with corresponding drilling fluid maintenance measures taken. Field using showed that the drilling fluid system solved the problem of well-bore instability caused by mudstone collapsing, gypsum dissolving and creeping; it ensured the success of tripping-in and cementing the 244. 5 mm and 250. 8 mm complex casing; it avoided the risk of mudstone and shale sloughing in the 5th section and minimized the influence of high downhole temperature on drilling fluid performance; it also solved the problem of cuttings suspension and transportation in the ultra-deep section with low flow rate; in addition, it was good for reservoir protection.