超深井高强度厚壁套管开窗侧钻技术难点与对策

Technical Difficulties of Sidetracking of High-strength Thick-wall Casing in Ultra-deep Wells and Countermeasures for Them

套管开窗侧钻是老井修复的常用方法;另外,由于发生断钻具或卡钻等事故,井下落鱼无法打捞出井,有的新井也需进行套管开窗侧钻作业。通过介绍套管开窗侧钻技术在四川油气田JT1井的现场应用,探讨了高强度厚壁套管开窗侧钻技术的关键要点和难点。现场两次开窗均发生卡钻事故,说明目前的套管开窗技术对高钢级、厚壁套管开窗尚存在不足。开窗所用斜向器硬度不能低于套管硬度,所用较大切削齿铣锥很难在高钢级套管上磨铣出光滑、平整的窗口,且在修窗时容易发生阻卡。建议使用较小切削齿的圆头铣锥来减轻崩齿情况,延长磨铣时间让窗口光滑、平整,降低阻卡风险。

Casing windowing sidetracking is a common method for repair of old wells.In addition,some new wells also need casing win⁃dowing sidetracking due to accidents such as drilling tool breaking or sticking leading to falling fish to be not fishinged.By introducing the field application of casing windowing sidetracking technology in well JT1 of Sichuan oil and gas field,the key points and difficulties of the windowing sidetracking technology for high-strength thick-wall casing are discussed.The sticking accidents occurred in both on-site windowing indicate that the current casing windowing technology is still insufficient for high-strength thick-wall casing win⁃dowing.The hardness of the deflector used for windowing shall not be lower than that of the casing.The used milling cone with larger cutting teeth is difficult to mill a smooth and flat window on the high-grade steel casing,and it is easy to get stuck during window re⁃pair.It is suggested to use the round head milling cone with smaller cutting teeth to reduce the breaking of the tooth,prolong the milling time to make the window smooth and flat and reduce the risk of sticking during window repair.