摘要:
合理确定水力冲孔冲煤率，是保障水力冲孔措施取得良好卸压增透效果的关键，对指导不同煤层瓦斯赋存条件下，煤层瓦斯在规定预抽期内实现抽采达标具有重要意义。根据孟津煤矿的煤层瓦斯地质条件，运用数值模拟和现场试验的手段，研究了冲煤率对煤层卸压增透及瓦斯抽采效果的影响规律。结果表明：水力冲孔技术能够有效提高钻孔周围煤体的卸压范围，且随着冲煤率的增大，钻孔间煤体所处的应力状态，由邻近钻孔煤体处于卸压区、中部煤体处于增压区，逐渐过渡至两钻孔间所有煤体均处于卸压区。水力冲孔冲煤率越高，钻孔间煤体的卸压程度越大，引起煤体渗透率呈数量级的增大，邻近钻孔煤体的渗透率增大了上千倍，从而造成了抽采后煤层瓦斯含量的降低幅度越大，煤层瓦斯的预抽效果越好。应根据煤层的瓦斯赋存条件，选择合理水力冲孔冲煤率的煤层瓦斯预抽方案，对于厚煤区和瓦斯富集区，应加大水力冲孔冲煤率。采用预抽—水力冲孔—2次抽采的工序，可降低冲孔前钻孔周围煤体的瓦斯含量和瓦斯压力，使得水力冲孔期间钻孔发生喷孔的次数及强度显著降低，利于防治水力冲孔时发生喷孔及瓦斯的异常涌出。预抽时间越长，煤层的残余瓦斯含量越低，但随着抽采时长的增大，煤层残余瓦斯含量的降低速率有减缓趋势。基于上述研究成果，成功指导了孟津煤矿12050工作面不同煤层瓦斯赋存条件下，煤巷条带煤层瓦斯的安全高效预抽。
Abstract:
Reasonable determination of the hydraulic punching rate is the key to ensure the hydraulic punching measures can achieve good pressure relief and permeability improvement effects, and it is of great significance to meet the standard of coal seam gas drainage in the specified pre-drainage period for different coal seam gas conditions. According to the geological conditions of coal seam gas in Mengjin Coal Mine, the influence laws of coal punching rate on coal seam pressure relief, permeability improvement and gas extraction were studied by means of numerical simulation and field test.The results show that the hydraulic punching technology can effectively improve the pressure relief range of the coal mass around the boreholes, and with the increase of the coal punching rate, the stress state of the coal body between the boreholes gradually converts from stress relief zone and the stress concentration zone to stress relief zone. The higher the coal punching rate, the greater the degree of pressure relief of the coal body between the boreholes, resulting in an order of magnitudes increase for the coal permeability. The coal permeability adjacent to the boreholes increases by thousands of times, thus resulting in the greater reduction of the coal seam gas content after extraction, and the better the pre-extraction effect of coal seam gas. According to the gas occurrence conditions of the coal seam, a coal seam gas pre-extraction plan with reasonable coal punching rate should be selected. For thick coal areas and gas-enriched areas, the hydraulic punching rate should be increased. The process of gas pre-drainage, hydraulic punching-second gas extraction can reduce the coal seam gas content and gas pressure around the boreholes before hydraulic punching,so that the numbers and intensity of spraying holes during hydraulic piercing can be significantly reduced, which is conducive to prevent and control the occurrence of spraying holes and abnormal gas emission during hydraulic punching. The longer the gas pre-extraction time, the lower the residual gas content of coal seam. However, the reduction rate of residual coal seam gas content tends to slow down with the increase of the extraction time. The research results successfully guided the safe and efficient gas pre-drainage of coal roadway strip for working face 12050 with different coal seam gas conditions in Mengjin Coal Mine.
百度学术
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