深井超大环空小井眼安全钻井技术研究与应用——以蓬莱气区DB-1井为例

Research and Application of Safe Slimhole Drilling Technology for Deep Well with Ultra-large Annulus:A Case Study From Plenglai Gas Filed of Sichuan Basin

川渝地区因地质情况非均质性较强,在设计时为增加深井段、超深井段处理复杂的手段,通常采用备留一层技术套管封隔可能出现的、处理难度较大的复杂,若钻井施工比较顺利,备用套管未使用时,则会出现深井超大环空小井眼钻完井方式。若是目的层钻井液密度窗口窄,易漏、易塌,堵漏防塌难度大,钻完井作业则易发生卡钻事故。文章为了保障此类井的安全钻井,以蓬莱气区DB-1井为例,在分析了超大环空小井眼钻井难点——井筒清洁能力差及井漏预防和处理难度大,致使钻完井过程中易卡钻的基础上,研究制定了深井超大环空小井眼钻完井技术方案,通过优化钻井参数、钻井液性能、小井眼钻井工艺措施,形成了DB-1井深井超大环空小井眼安全钻井技术。现场应用后,DB-1井超大环空小井眼实现了安全钻完井作业,顺利完成了该井的钻探任务,对同类井安全钻井具有较好的指导意义。

Due to the strong reservoir heterogeneity in Sichuan-Chongqing area,in order to increase the means of handling downhole complexities in deep and ultra-deep well sections,a stand-by casing is often used during well design to block out potentially complexities,of which handling is more difficult.If the drilling operation is relatively smooth and the stand-by casing is not utilized,the drilling and completion method for deep slimhole well with ultra-large annulus will be implemented.If the drilling mud density window of target formation is narrow,easily causing leak and collapse,and it′s difficult to deal with,therefore,stuck pipe is likely to occur.To ensure the safe drilling of this kind of well,taking well DB-1 in Penglai gas area as an example,in this paper the difficulties of slimhole drilling for well with ultra-large annulus were analyzed,which includes poor well cleaning,difficulty in loss prevention and treatment and easy stuck pipe,and the technical solutions of this technology has been researched.The safe slimhole drilling technology for deep well with large annulus suitable for DB-1 well is formed through optimization of drilling parameters,drilling fluid properties and study of slimhole drilling supporting technologies.Through field application,it is proved that safe slimhole drilling and completion has been realized in well DB-1,and the drilling task of this well has been successfully completed,which has a good guiding significance for the safe drilling of similar Wells.