多次采动条件下煤层气地面井设计及工程应用研究

    Research on surface well design and engineering application of coalbed methane under multiple mining conditions

    • 摘要: 在分析多次采动对地面井变形破坏影响的基础上,构建了基于井身主要变形形式地面井综合变形破坏力学模型,推导出地面井的单侧最大剪切位移公式,之后设计了井位及选择适合多次采动条件下地面井井型结构,通过现场地面井抽采试验验证了该项技术的适用性。结果显示:采动地面井在1303上下两层工作面回采过程中,地面井保持完好,未有出现明显的变形及破损情况;同时该地面井平均抽采煤层气量1.58万m3/d,平均抽采浓度33.71%,累计抽采量3 655万m3,极大缓解了1303工作面的瓦斯治理压力,与地面井未运行前相比,运行后工作面瓦斯浓度平均降幅达30%,回风巷瓦斯浓度下降幅度达到58.75%,回风巷平均瓦斯浓度仅0.33%,风排瓦斯量降为地面井未运行时的70%,显著地降低了回采面上隅角及回风巷瓦斯浓度,成功地消除了瓦斯涌出对工作面回采的制约。为多次采动条件下地面井的设计及运行提供了参考。

       

      Abstract: On the basis of analyzing the influence of multiple mining on surface well deformation and failure, the comprehensive deformation and failure mechanical model of surface well based on the main deformation forms of well body is constructed, and the single maximum shear displacement formula of surface well is deduced. Then the well location is designed and the well structure suitable for multiple mining is selected. The applicability of this technology is verified by field surface well extraction test. The results show that the surface well remains intact without obvious deformation and damage during the mining process of 1303 upper and lower working faces. At the same time, the average coal seam gas extracted by the surface well is 15 800 m3/d, the average extraction concentration is 33.71%, and the cumulative extraction volume is 36.55 million m3, which greatly alleviates the gas control pressure of the 1303 working face. Compared with the surface well before operation, the average gas concentration of the working face decreases by 30% after operation. The gas concentration in the return air roadway decreases by 58.75%, the average gas concentration in the return air roadway is only 0.33%, and the gas exhaust volume decreases to 70% of that before the surface well is in operation, which significantly reduced the gas concentration in the corner of the mining face and in the return air roadway, and successfully eliminated the restriction of gas gushing to the mining face. It provides a reference for the design and operation of surface well under multiple mining conditions.

       

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