铁法矿区高瓦斯低透气性煤层群卸压煤层气抽采钻孔布置

Boreholes layout of coal mine methane drainage for high gassy and low permeability coal seams in Tiefa coalfield

基于铁法矿区高瓦斯低透气性煤层群地质及开采技术条件,采用物理模拟方法系统分析了煤层群不同开采顺序时采动裂隙演化特征,运用CFD(Computational Fluid Dynamics)Fluent分析了U型负压通风条件下采空区瓦斯流动规律,总结了铁法矿区卸压煤层气抽采钻孔布置原则。研究结果表明:回采巷道内侧约在工作面倾斜长度的1/3处为采动裂隙发育区、距回风巷30～80 m范围为高浓度瓦斯富集区。铁法矿区煤层气抽采钻孔布置的原则为:垂直方向上钻孔终孔位置布置在断裂带下1/3处、地面钻井的合理间距不小于100～150 m、沿工作面倾斜方向靠回风巷(1/3～1/2)工作面斜长范围为最佳的钻孔位置。

Based on the high gassy and low permeability coal seams geo-conditions and developing technology in Tiefa coalfield,the features of mining-induced fractures with different mining orders,gas migration under U model exhaust ventilation,and boreholes layout of methane drainage were studied by means of physical simulation and CFD（Computational Fluid Dynamics） numerical modeling.The results show that mining-induced fractures are mainly generated on the inside of the retreat drift,around 1/3 along the retreat direction and the zone where gas mainly flows range from 30 to 80 m away from the tailgate.Arising from this,it can be derived that the boreholes should be drilled vertically with a distance that is the summation of caved zone height and 1/3 fractured zone height to the coalface roof,the separation distance should be no less than 100~150 m for surface boreholes,and the best location for the boreholes should be with a distance of 1/3~1/2 inclination.