塔里木博孜区块超深井自动垂直钻井难点与技术对策

Difficulties and Technical Countermeasures for Automatic Vertical Drilling in Ultra-Deep Wells in the Bozi Block of the Tarim Basin

塔里木盆地博孜区块属于典型的山前高陡构造,地层倾角大、自然造斜能力强、防斜打直难,采用常规的防斜打直技术难以保证井斜控制效果。为此,分析了自动垂直钻井技术在博孜区块超深井的应用难点,针对博孜区块上部砾岩地层的井下钻具振动大、防斜打直难等情况,开展了减振优化、超深井信号传输和防斜打直工艺优化等方面的技术研究。BZ1501井一开198~417及565~1000 m井段应用了自动垂直钻井系统,两趟钻累计工作循环时间281 h,平均机械钻速2.43 m/h,井斜角0.2°,与该井应用常规钟摆钻具组合及BZ18井应用自动垂直钻井系统相比,工作寿命长,机械钻速快,井斜控制效果好。现场应用表明,超深井防斜打直钻井技术在塔里木博孜区块的钻井提速效果较好,可以在该区块推广应用。

The Bozi Block of the Tarim Basin belongs to a typical piedmont high steep structure that has a large dip angle and strong natural deviation capacity,which is difficult for deviation-prevention straight drilling.It is hard to ensure the hole deviation control effect by using conventional deviation-prevention straight drilling technology.This paper analyzes difficulties in the application of automatic vertical drilling technology in ultra deep wells of the Bozi Block.In view of the strong downhole vibration and the difficulty in deviation prevention during straight drilling in the upper conglomerate formation of Bozi Block,research on deviation-prevention technology was carried out on a number of different aspects.They included damping optimization,ultra deep well signal transmission,the optimization of deviation-prevention straight drilling process,etc.The automatic vertical drilling system was applied in the spud in sections of 198–417 m and 565–1000 m in Well BZ1501.The cumulative working time of two trips was 281 h,the average ROP was 2.43 m/h,and the hole deviation was 0.2°.Compared with the conventional pendulum drilling string used in this well and the automatic vertical drilling system in Well BZ18,the system had the advantages of long service life,high ROP and good deviation control effect.The field application demonstrated that the deviation-prevention straight drilling technology could be successfully implemented for ROP enhancement in the ultra deep wells of the Bozi Block in the Tarim Basin,and its application could be popularized in the block.