穿层钻孔煤层掏穴扩孔强化增透技术研究

Research on Enhanced Permeability Technology by Enlarging Diameter of Cross-seam Boreholes in Coal Seam Section

为提高低透煤层瓦斯抽采效果,提出了一种掏穴扩孔增透技术。以李嘴孜矿A1煤为研究对象,通过现场测试与分析,考察了A1煤掏穴扩孔前后瓦斯抽采影响半径,抽采浓度和抽采纯量;同时采用RFPA2D-Flow模拟软件模拟了扩孔前后煤层裂隙的起裂及扩展过程,分析了掏穴扩孔钻孔对煤层透气性的影响。结果表明:掏穴扩孔钻孔增加了钻孔内壁表面积,增大周围煤体裂隙,使得周围煤体中的应力得到释放。掏穴扩孔后,瓦斯抽采影响半径提高了1.3倍,抽采浓度提高1.9倍,抽采纯量提高了2.3倍,因此,掏穴扩孔钻孔具有提高钻孔瓦斯抽采效果,达到快速消突的目的。

In order to improve the effect of gas drainage in coal seam of low permeability,a permeability improvement technology by enlarging diameter of boreholes was proposed. Taking A1 coal seam of Liyi Coal Mine as the research object,by field test and analysis,the size of the radius of influence for gas drainage,concentration and volume of gas drained before and after boreholes being enlarged were investigated. By using numerical simulation software RFPA2D- Flow,the process of crack starting and extension of coal seam before and after boreholes being enlarged was simulated,and the influence of borehole enlargement on permeability of the coal seam was analyzes. The results showed that by enlarged borehole the wall surface area of boreholes increases,and fractures in coal seam around boreholes increase,thus the stress in the coal body around the boreholes was released. The gas drainage radius after borehole being enlarged increased by 1. 3 times,concentration of gas drained increased by1. 9 times and the volume of gas by 2. 3 times. The technology improves gas drainage effect,and fast eliminates outburst of coal and gas.