Tashan Mine, Datong Coal Mine Group Corporation Limited

为揭示瓦斯在深部煤层抽采时的渗流机理,基于深部煤层低渗透率、高地应力、高瓦斯压力特征,结合瓦斯运移的Klinkenberg效应,建立了考虑煤体基质、裂隙双重孔隙介质的瓦斯抽采气固耦合模型,并针对具体地质情况进行了耦合模型的数值模拟研究。结果表明:煤层瓦斯压力随抽采时间增长呈下降趋势,钻孔周围出现瓦斯压降漏斗现象,距钻孔越近瓦斯压力下降越明显。深部低渗透煤层瓦斯抽采过程中,煤层体积变形、瓦斯解吸共同影响煤层渗透率变化,瓦斯抽采使煤层瓦斯压力逐渐降低,煤体发生收缩变形导致渗透率增大,同时煤层有效应力增大,煤层中裂隙、基质受压变形,又会导致渗透率逐渐减小。

In order to reveal a gas percolation mechanism in the gas drainage from a deep seam, based on the low permeability, high ground stress and high gas pr essure features of the deep seam, in combination with Klinkenberg effect of the gas migration, a gas-solid coupling model of the seam gas drainage was established in consideration of the coal matrix and crack double porous medium. And according to the certain geological condition, a study was conducted on the numerical simulation of the coupling model. The results showed that the seam gas pressure would be in a decreasing tendency with the gas drainage time increased, a hopper phenomenon of the gas pressure drop was occurred around the borehole and the gas pressure more closed to the borehole would be decreased obviously. During the gas drainage p rocess of the deep and low permeability seam, the seam volume deformed and the gas desorption would be jointly affected to the variation of the seam permeability an d the gas drainage could make the seam gas pressure steadily reduced. The shrinkage and deformation occurred in the seam would cause the permeability increased. Meanwhile, the effective stress of the seam increased and the pressure deformation of the cracks and matrix in the seam would cause the permeability steadily reduce d.