煤矿区大口径井二开先导孔下导管钻进技术

煤矿区大口径井施工过程中，基于钻井安全考虑须首先完成一开表土层钻进，但其固井用大口径钢管会造成二开先导孔排渣不利，影响钻进效率。为解决先导孔钻进循环问题，通过理论分析和现场对比试验，提出下导管钻进技术。实践表明，下导管钻进技术对于大口径井二开先导孔钻进具有重要的借鉴意义。

Drilling technology with guide pipe in the second section pilot hole of large-diameter well in coal mining area

In the process of large-diameter well construction, it's necessary to complete the first section drilling and cement with large-diameter pipe in the surface hole to reduce the risk of subsequent reaming. But this step could lead the pilot hole of the second section to reduce drilling speed as carrying cuttings incompletely. Finally we have put forward setting guide pipe drilling technology to solve the cycling problems by means of theoretical analysis and site comparative test. Practices show that it has important referential value for the second section drilling of large-diameter well by using drilling technology with guide pipe.