本煤层顺层预抽瓦斯钻孔间距数值模拟研究

煤层瓦斯流动存在启动压力，在预抽钻孔抽采瓦斯的后期瓦斯渗流出现非Darcy渗流的现象，同时煤层瓦斯压力、吸附膨胀应力、有效应力等物性参数亦发生改变。为得到为得到启动压力对抽采的影响作用，基于煤岩弹性理论和瓦斯渗流理论，研究了在启动压力作用下非Darcy渗流现象，得到了考虑启动压力的达西定律，建立了考虑启动压力、地应力、吸附膨胀应力、孔隙压力共同作用的煤岩瓦斯流固耦合数学模型。采用建立的模型对漳村煤矿2601工作面瓦斯抽采钻孔间距进行数值模拟研究，研究结果表明:建立的考虑启动压力的煤岩瓦斯流固耦合数学模型具有一定的可靠性，一定负压下启动压力影响钻孔抽采范围。最终给出了漳村煤矿2601工作面预抽钻孔抽采设计参数。

Study on numerical simulation of borehole spacing for gas pre-drainage along coal seam

When conducting gas drainage through the pre-drainage borehole, the phenomenon of non-Darcy seepage will occur for gas seepage in the later period of drainage, and the coal seam gas pressure, the adsorption swelling stress, the effective stress and other physical parameters will change. There exists the starting pressure for gas flow in coal seam. To obtain the influence of starting pressure on the drainage, the phenomenon of non-Darcy seepage under the effect of starting pressure was studied based on the coal and rock elasticity theory and the gas seepage theory. The Darcy's law considering the starting pressure was obtained, and a mathematical model with fluid-solid coupling of coal and rock gas considering the combined effect of the starting pressure, the geostress, the adsorption swelling stress and the pore pressure was established. The numerical simulation on the borehole spacing for gas drainage in the 2601 working face of Zhangcun coal mine was carried out by using the model. The results showed that the mathematical model with fluid-solid coupling of coal and rock gas considering the starting pressure has certain reliability, and the starting pressure will influence the borehole drainage range under a certain negative pressure. Finally, the design parameters of pre-drainage borehole drainage in the 2601 working face of Zhangcun coal mine were put forward.