低渗煤层高压水射流割缝强化瓦斯抽采技术研究

Study on high pressure water jet slotting technology for enhancing gas drainage in low permeability coal seam

为了解决低渗高突煤层瓦斯治理工程量大、效率低难题,提出在煤层中利用高压水射流切割缝槽依靠煤岩自身重力自动卸压强化瓦斯抽采技术。为了确定超高压水射流割缝工艺参数,采用FLAC3D数值模拟方法分析了不同缝槽间距、宽度条件下缝槽周围煤体塑性破坏特征和应力演化规律,得出高压水射流割缝合理缝槽间距为3m,合理缝槽宽度为100mm,现场实践表明:高压水射流割缝增大了煤层暴露面积、煤体扰动体积,高负压抽采支管瓦斯流量和浓度显著提升,瓦斯抽采纯量在0.7~1.1m^3/min范围内波动,瓦斯浓度在50%以上,对该矿其他工作面瓦斯治理具有一定借鉴意义。

In order to solve the problems of large engineering quantity and low efficiency of gas control in the low permeability and high outburst coal seam,it was proposed to use the high pressure water jet to cut slots in the coal seam,thus enhance the gas extraction by automatically relieving pressure depending on their own gravity of coal and rock. In order to determine the technological parameters of ultra-high pressure water jet slotting,the plastic failure characteristics and stress evolution laws of coal around the slot under different slot spacing and width conditions were analyzed by using the FLAC3D numerical simulation method. It was concluded that the reasonable slot spacing of ultra-high pressure water jet slotting was 3 m,and the reasonable slot width was 100 mm. The field practice showed that the ultra-high pressure water jet slotting increased the exposed area of coal seam and coal disturbance volume,and the gas flow and concentration of high negative pressure extraction branch pipe increased significantly. The pure quantity of gas extraction fluctuated in the range of 0. 7-1. 1 m3/min,and the gas concentration was more than 50%. It has a certain reference significance for gas control in other working faces of the mine.