大直径反循环潜孔锤的密封方法与试验研究

Sealing Method for Large-diameter Reverse Circulation DTH and the Experimental Study

摘要:

可靠的密封结构是大直径反循环潜孔锤能够实现反循环钻进工艺的关键，同时也是大直径反循环潜孔锤设计的难点。现有的大直径反循环潜孔锤都是基于孔底钻具本体进行密封结构设计的。提出了一种孔底与孔口联合密封的方法，以该密封方法为设计原则研制了扩孔用φ710/311 mm集束式反循环潜孔锤与孔口密封装置，并配套φ127/70 mm双壁钻具进行了现场试验，取得了较好的连续反循环排渣效果，平均机械钻速为2.1 m/h，与常规牙轮钻头扩孔方法相比提高了2.6倍。试验结果表明孔底与孔口联合密封方法是可行的，值得进一步推广应用。

Abstract:

Reliable sealing structure is the key to use the reverse circulation drilling technology for large-diameter reverse circulation DTH and is also the design point of large-diameter reverse circulation DTH. The sealing structure of existing large-diameter reverse circulation DTH is designed on basis of BHA body structure. A double sealing method at bottom and entrance of drilling hole is proposed in this paper, based on which as design principle, φ710/311mm cluster reverse circulation DTH and entrance sealing device were developed for reaming, the field test was made matching with φ127/70mm double-wall drilling tool, continuous reverse circulation effect was realized, the average ROP was 2.1m/h which was 2.6 times of the ROP of roller bit used in the same hole. The test results show that the double sealing method at bottom and entrance of drilling hole is feasible and it is worthy to be popularized.