顺煤层超长定向孔滑动减阻钻进关键技术研究

    Research on key technology of sliding drag reduction drilling along ultra-long directional hole in coal seam

    • 摘要: 煤矿井下大盘区瓦斯治理客观上要求顺煤层超长定向钻孔长度达到3 000 m以上,受制于目前煤矿井下定向钻进技术与装备,顺煤层钻孔滑动定向钻进最大孔深不超过2 000 m;从定向钻进工艺角度出发,对超长定向钻孔滑动钻进过程中钻进阻力影响因素进行分析,并从理论分析和实钻数据统计的基础上揭示了超长定向钻孔滑动钻进阻力随孔深的变化规律,得出钻具与孔壁之间摩擦阻力随孔深增加加速上升是制约钻进深度的根本原因;基于此开发出煤矿井下水力加压减阻钻进技术及正反扭转减阻钻进技术,分别从改善孔底钻具受力状态和孔口钻具滚动摩擦替代滑动摩擦出发,有效缓解超长定向钻孔钻具托压问题;在保德矿二盘区81210工作面进行了现场应用。试验结果表明:水力加压钻进将钻进阻力缓慢线性增长区域从1 000 m以内提升至1 500 m以内,正反扭转钻进将2 000 m以后滑动钻进压力降低了2~4 MPa,通过水力加压钻进及正反扭转钻进技术结合成功将滑动定向钻进深度提升至2 700 m,有效提升了超长定向钻孔轨迹控制精度及钻孔长度,为大盘区瓦斯抽采提供技术保障。

       

      Abstract: The gas control in large panel of underground coal mine objectively requires the length of ultra-long directional drilling along the coal seam to reach more than 3 000 m, however, restricted by the current directional drilling technology and equipment in underground coal mine, the maximum hole depth of directional sliding drilling along coal seam is less than 2 000 m. This paper starts from the point of view of directional drilling technology, the influencing factors of drilling resistance in sliding drilling process of ultra-long directional drilling are analyzed, and on the basis of theoretical analysis and statistics of actual drilling data, the variation law of sliding drilling resistance with hole depth is revealed, it concluded that the friction resistance between the drilling tool and the hole wall increases with the increase of the hole depth, which is the fundamental reason that restricts the drilling depth, based on this, the hydraulic pressure drag reduction drilling technology and the forward and reverse torsional drag reduction drilling technology are developed, it starts from improving the stress state of bottom hole drilling tool and replacing sliding friction with rolling friction, effectively alleviate the problem of supporting pressure of drilling tools in ultra-long directional drilling, the field application was carried out in the 81210 working face of the second plate area of Baode Coal Mine, the test results show that the slow linear growth zone of drilling resistance is improved from less than 1 000 m to less than 1 500 m by hydraulic pressure drilling, the forward and reverse torsional drilling reduced the sliding drilling pressure by 2 MPa to 4 MPa after 2 000 m, using a combination of hydraulic pressure and positive and reverse torsional drilling techniques, directional sliding drilling was successfully achieved to a depth of 2 700 m, effectively improve the control precision of ultra-long directional drilling trajectory and drilling length, and provided technical support for gas extraction in large panel.

       

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