软厚煤层液态CO2相变多点致裂增透技术

Permeability Increasing Technology by Using Liquid CO2 Phase Transition Multi-Discharge Crack in Soft Thick Coal Seam

针对松软、低透气性高瓦斯突出厚煤层瓦斯抽采效率低、抽采钻孔瓦斯浓度衰减快等问题,利用优化的液态CO 2相变致裂系统,在长平矿4306采区进行了(底板)穿层钻孔多点致裂试验。试验结果表明:CO 2相变多点致裂有效影响半径约为12.5 m,且与致裂点数无关;瓦斯浓度随致裂点数的增加呈线性增加;CO 2相变致裂提高了瓦斯抽采浓度,随着时间的推移瓦斯浓度逐渐下降。因此,在煤层的不同位置和不同的时间对煤层进行致裂,是维持或提高煤层瓦斯抽采效率的可选方案。

In view of the problem in soft thick coal seam with low permeability and high gas content outburst, such as the gas extraction efficiency is low, the gas concentration of extraction borehole decreases quickly, by using the optimized liquid CO 2 phase transition fracturing system, the multi-point fracturing test of perforating borehole (floor) in 4306 mining area of Changping Coal Mine was carried out. The experimental results show that the effective influence radius of multi-discharge crack of CO 2 phase transition is about 12.5 m, and it is independent of the number of cracking points;the gas concentration increases linearly with the number of cracking points;the concentration of gas extraction is increased by CO 2 phase transition cracking, and decreases with time going on. Therefore, it is an alternative to maintain or improve the gas extraction efficiency of coal seam to crack the coal seam at different locations and different times.