采动区地面井瓦斯抽采技术在新疆大倾角煤层中的应用

    Application of surface well gas extraction technology in mining area of steeply dipping coal seam in Xinjiang

    • 摘要: 在深入分析采动区地面井抽采效果和地面井结构稳定性的基础上,结合新疆煤层倾角大的赋存特点,针对不同倾角及瓦斯赋存条件,井位选择布置在套管剪切位移最小的工作面拐点附近,同时对采动区地面井结构的开井次数、钻头规格等合理组合进行了优化,井身结构、钻完井工艺、安全防护装置等方面用“避”“抗”“让”“疏”“护”地面井五大设计防护理念,形成一套适合的大倾角煤层采动区瓦斯地面抽采井设计技术。之后在二一三〇煤矿4号煤层24223工作面施工1口采动地面井进行瓦斯抽采。试验结果显示:采动区地面井平均瓦斯抽采浓度31.5%,日平均瓦斯抽采纯量850 m3/d,累计瓦斯抽采量达60.52万m3,地面井采气占比56.67%,降低了风排瓦斯的压力,保障了工作面的顺利回采。当工作面推过90 m时用智能钻孔成像仪对该地面井进行了现场投放观测,在二开套管内下放过程中未发现钻井套管产生异常变形情况,地面井未发生变形破坏,表明地面井在工作面推过后井身结构稳定,该井结构设计合理,能够保证地面井的持续抽采。

       

      Abstract: On the basis of in-depth analysis of the extraction effect of surface well in mining area and the stability of surface well structure, combined with the occurrence characteristics of Xinjiang coal seam with high dip angle and gas occurrence conditions, the well location is selected and arranged near the turning point of the working face with the minimum casing shear displacement. At the same time, the rational combination of the well structure in mining area and drill bit specifications is optimized. Five design and protection concepts of “avoid” “resist” “let” “thin” and “protect” surface wells are used in well structure, drilling and completion technology and safety protection devices to form a set of suitable design technology of gas surface extraction well in mining area of steeply dipping coal seam. After that, a mining surface well is constructed at 24223 working face of No.4 coal seam in 2130 Coal Mine to carry out gas extraction. The test results show that in the mining area, the average gas extraction concentration of surface wells is 31.5%, the average pure gas extraction volume of daily gas extraction is 850 m3/d, and the cumulative gas extraction volume reaches 605 200 m3, and the gas recovery of surface wells accounts for 56.67%, which reduces the pressure of wind exhaust gas and ensures the smooth mining of working face. When the working face is pushed over 90 m, an intelligent borehole imager is used to carry out on-site observation of the surface well. No abnormal deformation of the drilling casing is found in the process of lowering the second casing, and no deformation and damage occurred in the surface well, indicating that the structure of the surface well is stable after the working face is pushed, and the structural design of the well is reasonable, which could ensure the continuous extraction of the surface well.

       

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