孤岛工作面碎软煤层跟管护孔钻进工艺研究

Research on pipe-following hole protection drilling technology in broken soft coal seam of the isolated island working face

  • 摘要: 针对孤岛工作面高应力碎软煤层钻孔易卡钻、塌孔导致钻孔成孔难度大、瓦斯抽采效果差的问题,开展跟管护孔钻进工艺研究。选取王坡煤矿3206孤岛工作面作为试验地点,分析得出该工作面需要采用大转矩、高转速钻机,以增强钻具排渣效果及孔内事故处理能力,同时需要考虑高应力区段钻孔护壁工艺及孔内高效排渣工艺。提出采用跟管护孔钻进工艺过高应力区,以达到护壁效果;采用螺旋钻进氮气辅助排渣工艺,以增强排渣能力,降低钻进过程中煤炭自燃的风险;钻孔穿过高应力区后,通过优化钻具组合,进一步提高钻孔在碎软煤层中的成孔深度。现场试验结果表明:相比于直接采用回转钻进施工钻孔,采用二级护孔钻进工艺施工钻孔平均孔深提高149%,采用三级护孔钻进工艺施工钻孔平均孔深提高114%,说明跟管护孔钻进工艺比回转钻进工艺更适合3206孤岛工作面碎软煤层钻孔施工;插接式螺旋钻杆施工钻孔成孔率高于丝扣连接式螺旋钻杆,螺旋钻进氮气辅助排渣工艺的成孔深度明显大于干式螺旋排渣工艺; \textϕ100/63.5−28 mm插接密封式螺旋钻杆及氮气辅助排渣工艺最适合3206孤岛工作面瓦斯预抽钻孔施工,平均孔深为100.6 m,成孔率为80%,瓦斯抽采效果优于其他钻具及钻进排渣工艺。

     

    Abstract: It is easy to get stuck and collapse in the borehole of high stress and broken soft coal seam in the isolated island working face. This leads to great difficulty in borehole formation and poor gas extraction effect. In order to solve this problem, this paper puts forward a pipe-following borehole protection drilling technology. The 3206 isolated island working face of Wangpo Coal Mine is selected as the test site. It is analyzed that the working face needs to use high-torque and high-speed drilling rig to enhance the slag removal effect of the drilling tool and the capability to deal with accidents in the borehole. At the same time, it is necessary to consider the process of drilling wall protection in the high-stress section and the efficient slag removal process in the borehole. It is proposed to adopt the pipe-following borehole protection drilling technology in the high stress zone to achieve the effect of wall protection. The spiral drilling nitrogen-assisted slag removal process is adopted to enhance slag removal capacity and reduce the risk of coal spontaneous combustion during drilling. After the borehole passes through the high-stress area, the drilling depth of the borehole in the broken soft coal seam is further improved by optimizing the drilling tool assembly. The field test results show that the average hole depth is increased by 149% when using the second-stage hole protection drilling than when using rotary drilling directly. The average hole depth is increased by 114% when using the third-stage hole protection drilling. It shows that the pipe-following hole protection drilling is more suitable for the drilling construction of broken soft coal seam in 3206 island working face than the rotary drilling construction technology. The hole-forming rate of the plug-type screw drill pipe is higher than that of the screw thread-type screw drill pipe. The hole-forming depth of nitrogen assisted slag removal process for screw drilling is significantly greater than that of the dry screw slag removal process. \textϕ 100/63.5-28 mm plug-in sealed spiral drill pipe and nitrogen assisted slag removal process are most suitable for gas pre-extraction drilling construction in 3206 isolated island working face. The average hole depth is 100.6 m, and the hole formation rate is 80%. The gas extraction effect is better than other drilling tools and drilling slag removal technology.

     

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