桂中-南盘江地区黔水地1井卡钻事故处理及原因分析

Treatment and Cause Analysis of Sticking Accident in Well Qianshuidi 1 in Guizhong-Nanpanjiang Area

黔水地1井是大口径的页岩气地质调查井,设计井深2500 m。钻至井深2168.3 m起钻时,因井眼垮塌导致卡钻。尝试憋压、震击、套铣、打捞等多种处理措施均无效,被迫填井侧钻。后顺利钻至设计井深,各项工程参数均满足变更设计的要求。从泥页岩特征、钻井液性能、钻具组合及风险意识等方面对卡钻原因进行分析得出:增加钻井液中钾离子的含量,或提高抑制性;压井时不盲目增加泥浆密度,避免因泥浆密度过大引起诱导裂缝性井漏;采用合理的钻具组合,提高风险意识等措施保障施工顺利进行。该次事故的产生原因和处理经验对类似工程的施工具有借鉴意义。

Well Qianshuidi 1 is a large-diameter shale gas geological survey well,and its design depth is 2500 m.When drilling to a depth of 2168.3 m and pulling out of hole,the drilling string stuck due to hole collapse.Many treatment measures such as bit bounc⁃ing,jarring,casing milling and fishing are ineffective,and it is forced to sidetrack.Then drilling to the designed well depth smoothly,all engineering parameters meet the requirements of design change.The causes of sticking are analyzed in terms of shale characteris⁃tics,drilling fluid performance,BHA and risk awareness.It is concluded that increasing the content of potassium ion in drilling fluid to improve its inhibition,not blindly increasing the mud density during well killing to avoid induced fracture lost circulation owing to ex⁃cessive mud density,using reasonable BHA,improving risk awareness and fine operation are the effective guarantee for the safe and smooth drilling construction of Dawuba Formation.The causes and treatment experience of the accident are of important reference sig⁃nificance for the construction of this area and similar projects.