底抽巷穿层钻孔液态CO2相变致裂增透技术研究

为了提高松软、低渗煤层的瓦斯抽采效率，采用底抽巷穿层钻孔进行了液态CO2相变致裂试验。结果表明：煤层经历致裂后，致裂钻孔直径明显增大，瓦斯抽采影响半径为10m左右|钻孔瓦斯纯流量和瓦斯浓度均得到大幅提升，虽然每次致裂后期呈现一定程度衰减，但依然维持较高水平|与水力冲孔措施相比，液态CO2相变致裂后的前期增透效果更佳|液态CO2致裂不仅增强了煤层瓦斯抽采效率，也提高了矿井掘进速度，具有显著的安全和经济效益。

Study on Antireflection Technology of Liquid CO2 Phase-transition Fracturing for Layer-through Drilling in Bottom Drainage Roadway

In order to improve the gas drainage efficiency of soft and low permeability coal seam,liquid CO2 phase-transition fracturing test is carried out with drilling holes through floor drainage roadway.The results show that the diameter of the fracturing borehole increases obviously and the radius of gas drainage is 10 m after the coal seam fracturing.Both the pure gas quantity and gas concentration of borehole gas are greatly increased,it shows a certain degree of attenuation at the later stage of each fracturing though still remains at a high level.Compared with hydraulic flushing in hole,liquid CO2 phase-transition fracturing is better in early stage permeability enhancement,and the technology not only enhances the gas drainage efficiency,but also improves the tunneling speed,offering significant safety and economic benefits.