煤田地质与勘探2025，Vol.53Issue(5)：46-53,8.DOI:10.12363/issn.1001-1986.25.02.0087
低渗煤层胶囊二氧化碳相变致裂增透技术及应用
A phase transition-induced fracturing permeability enhancement technology using carbon diox-ide capsules for low-permeability coal seams and its application
摘要
Abstract
[Objective and Methods]To address engineering challenges like high gas content,high pressure,and low drainage efficiency in the mining of low-permeability coal seams,this study developed a phase transition-induced frac-turing and permeability enhancement technology using carbon dioxide(CO2)capsules for low-permeability coal seams.This technology leverages the feature that CO2 transitions into the supercritical state under high pressure.A capsule en-capsulating critical CO2 is placed into a conduit,which is then placed within a coal seam.Subsequently,phase transition-induced blasting is triggered using a heating blasting start device.Consequently,liquid CO2 vaporizes rapidly and ex-pands,generating high-pressure shock waves,which induce pre-fracturing of the coal seam.The fracturing process,pro-ducing no sparks,is prone to form fractures in coal seams,thus enhancing coal seam permeability.[Results and Conclu-sions]The results indicate that the technology developed in this study can effectively increase the quantity of fracture networks in coal seams,thereby significantly enhancing the coal seam permeability.Calculations reveal that during phase transition-induced fracturing,each capsule containing 1.4 kg of liquid CO2 can release explosive power equivalent to 243 g of trinitrotoluene(TNT).After secondary fracturing,the gas drainage influence radius gradually expands,indic-ating high timeliness.The field application effects demonstrate that this technology increased the pure gas drainage by 2 to 4 times,the volume fraction of methane by 2 to 3 times,and the gas drainage influence radius by 1.5 to 2.0 times.The field monitoring of the gas drainage effects of boreholes at 18,30,60,90,and 120 d reveals that the gas drainage influ-ence radius increased with time.Specifically,the influence radius increased rapidly in the initial stage,followed by a gradual decrease in the increasing amplitude.With time,the increasing amplitude of the gas drainage influence radius tended to level off,presenting a gradually stabilizing relationship with the drainage time.The effective drainage radius after fracturing measured from 2.45 m to 4.95 m.All these demonstrate that the fracturing technology developed in this study enjoys high timeliness and sustainability in gas drainage from coal seams.After fracturing,the permeability coeffi-cient of the coal seam in the study area increased significantly from 0.009 6 m2/(MPa2·d)to 0.577 m2/(MPa2·d).Addi-tionally,since CO2,as the medium inducing fracturing,can be sourced from industrial emissions or stored CO2,the frac-turing technology proposed in this study serves as a green permeability enhancement method,enjoying significant envir-onmental and social benefits.关键词
煤层增透/胶囊二氧化碳/相变致裂/超临界二氧化碳/致裂半径/瓦斯抽采Key words
permeability enhancement for coal seams/CO2 capsule/phase transition-induced fracturing/supercritical carbon dioxide/fracturing radius/gas drainage分类
矿山工程引用本文复制引用
李毛,范新川,符辉..低渗煤层胶囊二氧化碳相变致裂增透技术及应用[J].煤田地质与勘探,2025,53(5):46-53,8.基金项目
国家杰出青年科学基金项目(51925404) （51925404）
