青龙煤矿碎软煤层顺层定向钻孔钻进试验研究

Drilling experiment research on bedding directional drilling of soft—fragmentized coal seam of Qinglong Coal Mine

  • 摘要: 针对青龙煤矿碎软煤层瓦斯抽采钻孔成孔深度浅、轨迹控制精度低及瓦斯抽采效果差等问题,在分析矿井瓦斯地质情况与预抽采方式现状基础上,介绍了采用空气复合定向钻进技术进行顺层定向钻孔施工的原理和关键技术,制定了钻场与钻孔设计、钻进装备和钻具组合选套、钻进技术要求总结的整体试验方案,并在21608轨道巷迎头钻场进行了顺层钻孔空气复合定向钻进试验。试验结果表明,采用空气复合定向钻进技术可实现碎软煤层内顺层定向钻孔施工,完成7个主孔和2个主分支孔,总进尺为3 929 m,最大孔深达406 m,300 m以上钻孔成孔率达88.9%;试验钻孔瓦斯抽采体积分数均超过68%,平均单孔瓦斯抽采纯量超过1 m3/min,最大单孔瓦斯抽采纯量超过2.55 m3/min,抽采纯量是常规钻孔的10倍以上,瓦斯抽采体积分数提高了50%左右,钻孔成孔与瓦斯抽采效果显著。

     

    Abstract: For problems of shallow gas drainage hole depth, low control precision of drilling trajectory and poor gas drainage effect in soft—fragmentized coal seam of Qinglong Coal Mine, based on the analysis of mine gas geological conditions and existing pre—drainage modes, principle and key technologies of air compound directional drilling technology were introduced for bedding directional drilling construction, and a whole drilling experiment scheme was formulated including design of drilling field and borehole, selection of drilling equipment and assembly and summary of drilling technology requirements. A drilling experiment was carried out in 21608 roadway field. The experimental results show that bedding directional drilling construction in soft—fragmentized coal seam can be realized by the air compound directional drilling technology. 7 main boreholes and 2 main branch boreholes were completed, the total footage is 3 929 m, the maximum borehole depth reaches 406 m, and forming rate of borehole deeper than 300 m reaches 88.9%. Gas drainage volume fraction of experimental borehole is more than 68%, and the maximum gas drainage pure quantity of single borehole exceeds 2.55 m3/min with the average is more than 1 m3/min. Gas drainage pure quantity of the experimental borehole is more than 10 times of the one of conventional borehole, and gas drainage volume fraction increased about 50%, which verify the air compound directional drilling technology has good effect of borehole forming and gas drainage.

     

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