Abstract

In order to investigate the gas transport law of coal seams under the influence of mining, this paper selects coal samples from Dongpang mine for SEM experiments, and establishes a coupled model of coal rock damage deformation field and matrix diffusion-fracture percolation field based on the anisotropy of coal permeability, and uses COMSOL to study the gas transport law. The study shows that the non-homogeneity of the coal pore structure affects the matrix gas diffusion process, and the effective extraction radius in the parallel laminar direction is exponentially related to the extraction time, while the vertical direction is a power index function. The area around the borehole shows an elliptical pressure drop region, with a concave decline towards the centre of the borehole. A zone of sudden increase in permeability exists near the borehole and the radius of growth of the plastic zone increases linearly with increasing borehole diameter. The rate of decline in matrix pressure decreases as the diffusion decay coefficient increases and the fracture pressure changes in the opposite direction; the difference between the two pressures causes the change in seepage rate and gas extraction to be divided into a fast rising phase, a slow falling phase and a stable and constant phase. The effective extraction area of the seam increases exponentially with extraction time in relation to the initial permeability and the original pressure, and increases as a power function of borehole diameter and extraction time.

中文翻译：

---

开采影响下渗透性各向异性煤层瓦斯运移规律研究

摘要

为了研究开采影响下煤层瓦斯输运规律，选取东庞矿煤样进行扫描电镜实验，基于煤渗透率的各向异性，并使用 COMSOL 研究气体传输规律。研究表明，煤孔隙结构的不均匀性影响基质气体扩散过程，平行层流方向的有效抽采半径与抽采时间呈指数关系，而垂直方向则为幂指数函数。钻孔周围的区域显示出椭圆形的压降区域，并具有朝向钻孔中心的凹形下降。钻孔附近存在渗透率突然增加的区域，塑性区域的增长半径随着钻孔直径的增加而线性增加。基质压力下降速率随扩散衰减系数增大而减小，破裂压力向相反方向变化；两种压力的差异导致渗流速度和瓦斯抽采量的变化分为快速上升阶段、缓慢下降阶段和稳定恒定阶段。煤层的有效抽采面积相对于初始渗透率和原始压力随着抽采时间呈指数增加，并且作为钻孔直径和抽采时间的幂函数而增加。基质压力下降速率随扩散衰减系数增大而减小，破裂压力向相反方向变化；两种压力的差异导致渗流速度和瓦斯抽采量的变化分为快速上升阶段、缓慢下降阶段和稳定恒定阶段。煤层的有效抽采面积相对于初始渗透率和原始压力随着抽采时间呈指数增加，并且作为钻孔直径和抽采时间的幂函数而增加。基质压力下降速率随扩散衰减系数增大而减小，破裂压力向相反方向变化；两种压力的差异导致渗流速度和瓦斯抽采量的变化分为快速上升阶段、缓慢下降阶段和稳定恒定阶段。煤层的有效抽采面积相对于初始渗透率和原始压力随着抽采时间呈指数增加，并且作为钻孔直径和抽采时间的幂函数而增加。缓慢下降阶段和稳定恒定阶段。煤层的有效抽采面积相对于初始渗透率和原始压力随着抽采时间呈指数增加，并且作为钻孔直径和抽采时间的幂函数而增加。缓慢下降阶段和稳定恒定阶段。煤层的有效抽采面积相对于初始渗透率和原始压力随着抽采时间呈指数增加，并且作为钻孔直径和抽采时间的幂函数而增加。