煤层钻孔瓦斯抽放数值模拟

Numerical simulation of gas drainage from boreholes in coal seams

为了寻求合理的钻孔抽放参数,采用数值模拟的方法,应用计算流体力学软件fluent6.3建立了钻孔瓦斯抽放流动模型,通过气体渗流理论模拟抽放过程瓦斯流动规律,分析了抽放负压和煤层渗透率对瓦斯抽放效果的影响规律。结果表明:瓦斯抽放有效半径为2 m左右,抽放负压对抽放半径的影响不是很明显;瓦斯抽出量随抽放负压的升高而增加;煤层渗透率对瓦斯抽放量的影响比较大。模拟的抽放影响半径与现场实测结果基本一致。该模型可以对现场瓦斯抽放提供理论指导。

In order to seek the reasonable parameters of drilling drainage,the computational fluid dynamics method is used to establish the model of gas drainage.The Darcy law is applied to simulate the gas seepage flow in coal seams.The effect of drainage pressure and the permeability on the gas flow condition is analyzed.The results show that the effective gas drainage radius is about 2m,the impact of negative pressure on drainage radius is not very obvious.The gas volume increases with the increase of the negative pressure of extracted drainage.The impact of coal seam gas permeability on the gas volume is relatively large.The simulation results agree well with the measurement value,so the simulation result can provide theory guidance for gas drainage.