涪陵页岩气田加密井钻井关键技术

涪陵页岩气田加密井多处于页岩气压裂区且井网部署密集,导致钻井溢漏等井下故障多发、钻井液安全密度窗口确定难、压裂液侵入造成井壁坍塌及卡钻、防压裂干扰井眼轨道设计难度大等问题。针对上述钻井技术难点,从压裂区地层孔隙压力计算模型建立、合理钻井液密度窗口设计、防压裂干扰井眼轨道设计、加密井防漏堵漏和溢漏同存防控等方面进行了技术攻关,形成了适用于涪陵焦石坝主体区块的加密井钻井关键技术。该关键技术在涪陵页岩气田应用31口井,平均水平段长1 933.25 m,平均钻井周期52.38 d,平均机械钻速10.31 m/h,较前期加密评价井机械钻速提高了15.3%,钻井周期缩短了10.7%。涪陵页岩气田加密井钻井关键技术为涪陵页岩气田二期产能建设提供了技术支撑,也为其他页岩气田开发提供了技术参考和借鉴。

Key Drilling Technologies of Infill Wells in the Fuling Shale Gas Field

Infill wells in the Fuling Shale Gas Field are mostly located in the shale gas fracturing area with dense well pattern, resulting in many drilling technical problems, such as complex and frequent overflows and leakages, difficulty in determining reasonable drilling fluid density window, borehole collapse and sticking caused by fracturing fluid intrusion, and high difficulty in designing borehole trajectory to avoid fracturing interference, etc. To solve the above problems, technical research has been carried out from the perspectives of establishing a formation pore pressure calculation model for fracture zones, reasonable drilling fluid density window design, anti-fracturing interference borehole trajectory design, leakage prevention and plugging, and the prevention and control of simultaneous overflow and leakage in infill wells, etc., forming the key drilling technology suitable for infill wells in the Jiaoshiba main block of Fuling. The key technology has been applied in 31 wells in the Fuling Shale Gas Field, with an average horizontal interval of 1 933.25 m, an average drilling cycle of 52.38 days, and an average ROP of 10.31 m/h. Compared with previous infill evaluation wells, the ROP was increased by 15.3%, and the drilling cycle was shortened by 10.7%. The key drilling technology for infill wells in the Fuling Shale Gas Field provided technical support for the phase II productivity construction of the Fuling Shale Gas Field, and also provided technical references for the development of other shale gas fields.