本煤层单一顺层瓦斯抽采钻孔的渗流场数值模拟

Numerical simulation of seepage field of gas extraction drilling of single bedding of mining-coal bed

针对本煤层瓦斯抽采钻孔的合理布置问题,通过建立钻孔抽采瓦斯的渗流场控制方程和煤层变形场控制方程,结合钻孔抽采瓦斯的初始及边界条件,推导出钻孔抽采瓦斯渗流的固气耦合数学模型。以石壕煤矿本煤层单一顺层钻孔瓦斯抽采为工程实例,基于研究区域的煤层瓦斯赋存特征,采用数值模拟计算方法,获得了本煤层单一顺层钻孔周围煤层瓦斯压力、煤层瓦斯渗透率、煤层瓦斯渗流速度和煤层变形的分布规律。确定了本煤层单一顺层钻孔抽采瓦斯的有效影响半径,从而为本煤层单一顺层瓦斯抽采钻孔的优化布置提供了依据。研究结果表明,石壕煤矿本煤层单一顺层钻孔抽采瓦斯的有效半径分别为4m左右;在延长钻孔抽放时间不到20%的情况下,减少了钻孔工程量50%左右,抽采效果良好。

Aiming at the problem of reasonable decorate of coal gas extraction drilling,combining with the initial and boundary condition of borehole extraction,the solid and gas coupling mathematical model of gas seepage of borehole extraction is deduced based on established control equations of seepage field and deformation field.Taking gas extraction of stone coal slit as an example,according to the characteristics of coal seam in the research,the numerical simulation method is used to obtain the distribution rule of gas pressure,coalbed gas permeability,and coalbed gas seepage velocity as well as seam deformation.The effective radius of gas extraction drilling of single bedding about mining-coal bed is determined,which provides the basis for optimum arrangement of gas extraction drilling of single bedding.The results show that the effective radius of stone coal is about 4 m.If the prolonging drilling drainage time is less than 20%,the drilling quantities would reduce by about 50%.