水力压裂低透气性煤层裂隙扩展及瓦斯抽采技术应用

Application of Hydraulic Fracturing of Low Permeability Coal Seam Fracture Expansion and Gas Extraction Technology

为了解决石壕煤矿煤质软、渗透性低、瓦斯抽采效率低、封孔难等问题,利用理论分析、技术开发和现场实测相结合的方法,对低透性煤层水力压裂裂纹扩展特征进行分析,优化了传统的封孔技术,采用3次注浆封孔技术对水力压裂钻孔进行封孔处理,应用水力压裂技术增加低透气性煤层的渗透性,并对煤层的渗透性和瓦斯含量进行现场监测。研究结果表明,流体压力大于煤体的裂隙维持闭合状态的极限强度时,天然闭合裂隙会被扩展成为瓦斯气体流动通道;采用3次注浆封孔技术,封孔成功率100%;松软煤层水力压裂裂隙扩展范围可以达到42 m,与初始瓦斯浓度相比,3次水力压裂后,瓦斯浓度降低了60.5%。采用3次封孔和水力压裂技术能有效增加低透性松软煤层的渗透性,提高瓦斯的抽采效率,防止高瓦斯矿井出现煤与瓦斯突出事故,为矿井的安全生产提供有力的保障。

In order to solve the problems of soft coal,low permeability,low gas extraction efficiency and difficult sealing holes of Shihao Coal Mine.By combining theoretical analysis,technology development and field measurement,the crack propagation characteristics of hydraulic fracturing in low permeability coal seam are analyzed,and the traditional sealing technology is optimized.Three times grouting sealing technology is used to seal hydraulic fracturing boreholes,and hydraulic fracturing technology is applied to increase the permeability of low permeability coal seam.The permeability and gas content of coal seam are monitored on site.The results show that when the fluid pressure is greater than the ultimate strength of the coal fissures to maintain a closed state,the natural closed fissures will be expanded to become gas flow channels.The three times grouting sealing technology is adopted,and the sealing success rate is 100%.The hydraulic fracturing fracture expansion range of soft coal seam can reach 42 m.Compared with the initial gas concentration,the gas concentration is reduced by 60.5%after three times hydraulic fracturing.The use of three times grouting sealing and hydraulic fracturing technology can effectively increase the permeability of soft coal seams with low permeability,improve the efficiency of gas extraction,prevent coal and gas outburst accidents in high-gas mines,and provide a strong guarantee for the safe production of mines.