非常规短尾管固井技术在大斜度井的应用

中75井第四次开钻采用天然气钻井，井眼严重垮塌，井下情况比较复杂，仅钻进7.23 m即发生卡钻事故。为继续采用天然气钻井提供有利条件，正确评价中坝构造须三段目的层，决定对Φ152.4 mm井眼已钻大斜度复杂井段2351.24～2390.00 m进行尾管固井作业。鉴于尾管悬挂井段井斜角达67°,裸眼井段垮塌非常严重，井径极不规则，且已形成3个小井眼，尾管段长度超短，重量超轻，因而，若按常规方法操作，尾管下入、悬挂、倒扣等十分困难，风险极大；若无切实可行的技术措施，周密细致的施工方案，极可能导致该次固井失败，甚至引起新的事故发生，从而危及到钻井的成败。采用非常规短尾管固井技术，是该项技术在大斜度定向井的创新应用。该井的施工成功为大斜度定向井尾管固井作业提供了好的范例。

Application of Cementing Technique with Abnormal Short Liner to High-inclination Wells

Gas drilling was used while the forth spud in for Zhong Well 75. Severe collapse happened in the borehole. The accident of bit freezing took place at only 7.23 m. of footage drilled since the situation was complicated in the down hole. To provide the favor conditions for the following gas drilling and appraise the target bed of Xu Section 3 correctly in Zhongba structure, it is decided the well cementation with liner should be conducted for 2351.24—2390.00 m of the complicated high inclination interval Φ152.4 mm. of the drilled borehole. Since the deviation angle of the interval reaches 67°; the collapse is very severe in the open section; the borehole diameter is very irregular and 3 small boreholes have been formed; the liner is very short and light, it is very difficult and risky for the liner to put down, hang and screw off by conventional operation. Without feasible technical measures and thoughtful working program, it might have led fail of the cementing job and made new accident. By the cementing technique with abnormal short liner, the cementing job got success and provided good model for   high inclination directional wells to cement with liner.