东秋8井下尾管高密度油基防卡钻井液研究与应用

东秋8井是塔里木油田的一口重点预探井。该井在4772～530lm井段的钻井过程中因砂岩层渗透性好、油气层压力系数高，发生了多次井漏、溢流和压差卡钻等复杂事故，决定完钻，下入φ127mm尾管。为避免下尾管时出现压差卡钻等复杂情况，通过研究分析，优选出了高密度油基钻井液进行下尾管和固井作业。该钻井液抗温抗压能力强，性能稳定，与井浆配伍性好，经高温静置后，具有较高的携屑悬浮能力。现场应用表明，高密度油基钻井液密度范围宽、滤失量低、泥饼薄、泥饼的粘附系数小、高温高压稳定性好；能够大幅度降低泥饼的粘附系数，适合于深井超深井易发生压差卡钻井段测井、下套管等施工；东秋8井小眼井顺利下入尾管，固井作业顺利，解决了东秋8井下入尾管发生压差卡钻的难题，经济效益非常明显。

Study on high density oil-based drilling fluid and its application for liner running in Well Dongqiu-8

Well Dongqiu-8 is an important exploratory well in Tarim oilfield.Such accidents as lost circulation, well kick and differential pressure sticking occurred in section of 4772~5301 m because of high permeable sandstone and high formation pressure existence in this formation.Thus 127 mm liner was used and a high density oil-based drilling fluid which was suitable for liner running and cementing in the section was optimized.The drilling fluid has such properties as high temperature tolerance and high compressive resistance.It has good compatibility with mud and better carrying and suspension ability after quiescence in high temperature, as well as wide density range, low filtration, thin mud cake and low adhesion factor, and stability in HTHP environment, etc..Field using showed that the drilling fluid is suitable for using in logging and casing running in deep and ultra-deep section where differential pressure sticking easily occur.By using it, liner running was successfully carried out and cementing was smoothly operated in Well Dongqiu-8, while the problem of differential pressure sticking in the well was effectively solved.