西山矿区煤层CO2气相预裂增透技术应用研究

Application Study of CO2 Gas Pre-cracking and Permeability Enhancement Technology in Coal Seam of Xishan Mining

西山矿区煤层属低透气性难抽采煤层,致使瓦斯抽采出现钻孔间距小,抽采时间长,抽采成本较高等问题,造成矿井的瓦斯治理难题凸显。因此,通过分析CO2气相致裂煤层增透理论技术及成套装备,利用该技术在西山矿区部分高瓦斯与突出矿井进行了现场试验与应用。应用结果表明,CO2气相致裂增透技术能够有效增加煤层透气性,通过CO2和瓦斯竞争吸附驱替出更多游离态瓦斯,可有效降低煤层瓦斯含量及瓦斯压力,提高低透气性煤层瓦斯抽采效果。通过CO2预裂增透,预裂区域煤层瓦斯含量由10.03m^3/t降低至5.45m^3/t,钻孔百米抽采量增加为原来的2.9倍,单孔浓度提高到60%-80%,并能够长时间稳定,强化了瓦斯抽采效果,解决了低透气性煤层抽采浓度低、流量小、达标时间长的难题。

The coal seam in Xishan mining area is a low permeability and difficult to extract,which causes the problems of small borehole spacing,long extraction time and high extraction cost in gas extraction,and causes the difficult problem of gas control in the mine.Therefore,through the analysis of CO2 gas-phase fractured coal seam permeability enhancement theory technology and complete sets of equipment,the field test and application of this technology in some high gas and outburst mines in Xishan mining area were carried out.The application results show that CO2 gas phase fracturing and permeability enhancement technology can effectively increase the permeability of coal seam,accelerate the transformation of coal gas from adsorbed state to free state,and realize enhanced gas extraction in low permeability coal seam.Through CO2 pre-fracturing and permeability enhancement,the gas content of coal seam in pre-fractured area decreases from 10.03 m^3/t to 5.45 m^3/t,the extraction volume of 100-meter borehole increases to 2.9 times of the original,and the concentration of single hole increases to 60%-80%,which can be stable for a long time,strengthen the gas extraction effect,and solve the difficulties of low permeability coal seam extraction concentration,small flow rate and long time to reach the standard.question.