煤层瓦斯抽放半径及其影响因素的数值模拟

Numerical Simulation of Gas Drainage Radius and its Influencing Factors in Coal Seam

煤层瓦斯抽放半径是进行抽放方法选择,确定钻孔布置参数以及评价抽放效果的重要依据。为了确定有效抽放半径并找出其影响因素,采用数值模拟的方法,应用计算流体力学软件Fluent建立了钻孔抽放瓦斯模型。采用气体渗流理论模拟瓦斯抽放过程中的流动规律,确定了有效抽放半径,分析了钻孔直径、煤层渗透率和抽放负压对其影响的规律。结果表明:煤层瓦斯抽放有效半径为1.8 m左右,钻孔直径和煤层渗透率对抽放半径影响较大,抽放负压的影响不大。

Gas drainage radius in coal seam is an important basis to choose the drainage methods, determine the parameters of drilling layout and evaluate the drainage effect. In order to determine the effective drainage radius and find out its influ- encing factors, the numerical simulation method is used and the computational fluid dynamics software Fluent is applied to establish the model of gas drainage. The gas flowing law in drainage is simulated by using the Darcy law, the effective drainage radius is determined, and the effects of drilling diameter, the permeability of coal seam and drainage negative pres- sure on it is analyzed. The results show that the effective gas drainage radius is about 1.8 m,the impact of drilling diameter and the permeability on drainage radius is relatively large and the drainage negative pressure has little effect.