煤层瓦斯有效抽采半径与布孔间距的数值模拟

Numerical Simulation on Effective Drainage Radius and Spacing of Coal Seam Gas

为探索不同间距下的瓦斯抽采效果,基于煤体变形方程、瓦斯渗流方程、煤体孔隙率与渗透率变化方程,建立煤层瓦斯渗流场和煤层固体力学变形场的耦合模型.以邹庄煤矿7401工作面风机巷顺层钻孔抽采瓦斯为例,采用COMSOL数值模拟软件进行瓦斯抽采模拟,得到瓦斯抽采的有效半径和瓦斯抽采孔的最优布孔间距.结果表明:以直径为94 mm的钻孔预抽3个月,测得单孔抽采的有效半径为0.8 m;瓦斯抽采效果仅在小范围内受到钻孔直径的影响;瓦斯抽采效果几乎不受抽采负压的影响;多孔抽采时,最优布孔间距为1.6~4.8 m.

In order to explore the effect of gas drainage at different intervals,based on the coal deformation equation,gas seepage equation,coal porosity and permeability change equation,this paper establishes a coupling model of the seepage field of the gas in the coal seam and the solid mechanical deformation field of the coal seam.Taking the gas drainage along the bed in the fan lane of 7401 working face of Zouzhuang Coal Mine as an example,the gas drainage simulation is carried out based on the COMSOL numerical simulation software,and finally the effective radius of gas drainage and the optimal hole spacing of gas drainage holes are obtained.The results show that the drilling hole with diameter of 94 mm is pre-pumped for 3 months,and the effective radius of single hole pumping is measured to be 0.8 m.The effect of gas drainage is only affected by the diameter of borehole in a small range.The effect of gas extraction is almost not affected by the negative pressure of gas extraction.The optimal spacing of holes is 1.6~4.8 m in the case of multi-hole extraction.