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煤矿井下钻孔吞吐压裂增透抽采瓦斯技术研究

Study on Gas Drainage Technology of Throughput Fracturing Permeability Improvement by Borehole in Underground Mine

  • 摘要: 为了显著增大煤层透气性系数,达到高效抽采瓦斯的目的,提出了煤矿井下钻孔吞吐压裂增透抽采瓦斯技术,分析发现吞吐压裂实施过程中,在最大和最小水平主应力方向能够产生径向引张裂隙、周缘引张裂隙、剪切裂隙、转向裂隙等;同时,裂隙壁面错位支撑增容,形成了瓦斯运移产出的高速通道。现场试验表明:实施吞吐压裂与未采取瓦斯抽采措施相比,单孔瓦斯抽采纯量提高了7~12倍,瓦斯抽采体积分数提高4~5倍,钻孔瓦斯流量衰减系数降低了1/4~1/3;实施吞吐压裂与采取常规水力压裂相比:单孔瓦斯抽采纯量提高了1.6~3.0倍,瓦斯抽采体积分数提高1.2~2.0倍,钻孔瓦斯流量衰减系数降低了1/5~1/3。

     

    Abstract: In order to obviously enlarge the cofficient of the seam permeability and reach a target of the high efficient gas drainage, a gas drainage technology of t hroughput fracturing permeability improvement by borehole in underground mine was provided. It was found that during the operation of the throughput fracturing, radial guided fracturing, peripheral guided fracturing, shearing fracturing, turning fracturing and others occurred on the max and min horizontal main stress directions. The gas migration channel with a high speed was formed under the displacement support compatibilization of the borehole surface wall. The site experiments showed that after t he throughput fracturing conducted, in comparison with no measure conducted, the pure quantity of gas drainaged from a single borehole increased by 7 ~ 12 times, th e volume fraction of gas drainaged increased by 4 ~ 5 times, and the attenuation coefficient of the borehole gas flow reduced by 1 14~ 1 /3. In comparison with the con ventional hydraulic fracturing, the pure quantity of gas drainaged increased by 1. 6 ~ 3. 0 times, the volume fraction of gas drainaged increased by 1.2~ 2. 0 times, an d the attenuation coefficient of the borehole gas flow reduced by 1 /5~ 1 /3.

     

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