为了解决低渗透煤层抽采效率低、抽采时间长等难题,提出利用CO2高能气体预裂增透技术改造低渗透煤层,增大煤层透气性,提高瓦斯抽采量和抽采效率;通过分析低渗煤层高能气体预裂增透技术的卸压增透机理,制定了回采工作面和掘进工作面的高能气体预裂增透瓦斯抽采技术方案,并进行了现场试验和效果分析.结果表明:高能气体预裂能够在煤层形成裂隙卸压圈或裂隙卸压区,使圈(区)内煤层透气性和瓦斯解吸速度增高,掘进工作面预裂增透后的平均瓦斯抽采浓度、平均抽采纯流量和平均百米钻孔抽采纯流量分别增加了1.5、4.7、17.8倍;回采工作面预裂增透后,平均瓦斯抽采浓度、平均抽采纯流量和平均百米钻孔抽采纯流量分别增加了0.8、1.0、1.5倍.%In order to solve the low gas drainage efficiency,long gas drainage time and other problems of the low permeable seam,the CO2 high energy pre-fracturing and permeability improved technology was applied to reconstruct the low permeable seam,to improve the seam gas permeability and to improve the gas drainage volume and gas drainage efficiency.With the analysis on the pressure releasing and permeability improved mechanism of the high energy gas pre-fracturing and permeability improved technology for the low permeable seam,a gas drainage technology plan with the high energy gas pre-fracturing and permeability improvement was set up for the coal mining face and the excavated face.The site experiment and effect of the technology were analyzed.The results showed that the high energy gas pre-fracturing could form a crack and pressure released ring or the crack and pressure released zone in the seam and thus the seam permeability and gas desorption speed within the ring (zone) was improved.After the pre-fracturing and permeability improved of the gateway driving face,the average gas drainage concentration,average gas drainage pure flow and average gas drainage pure flow per 100 m borehole were individually increased by 1.5 times,4.7 times and 17.8 times.After the pre-fracturing and permeability improved of the coal mining face,the average gas drainage concentration,the average gas drainage pure flow and the average gas drainage pure flow per 100 m borehole were increased by 0.8 time,1.0 time and 1.5 times individually.
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