Abstract As for deep fuel exploitation of coal and gas,it is practical to study the gas flow characteristics of coal by considering a fractured medium. Coal samples containing different fracture networks were obtained in laboratory. The fracture network was quantitatively classified by an industrial computed tomography test. Several gas flow tests were conducted and classic permeability models were investigated in terms of their applicability to the prefractured coal samples. The main results are as follows: an index was defined to describe the complexity of the fracture network, and the complexity index of the fractured coal samples changes from 0.4 to 0.7. With an increase in the complexity index, the fractured coal permeability presents power-function growth. The maximum permeability ratios of prefractured coal samples to those without prefracturing reached to over 300 times, respectively. With the effect of gas pressure, the fractured coal presents 5 typical permeability evolution patterns. The increase in confining pressure weakens the compression effect of the effective stress on the fracture network and enhances the possibility that the gas adsorption shrinkage effect on the coal matrix. Considering the effect the prefractured fracture network, the new empirical permeability model can give a good description for the permeability evolution of fractured samples, which is in accord with the experimental phenomena of permeability rebound and recovery.

中文翻译：

---

不同裂缝网络复杂度煤样气体流动特性试验研究

摘要 对于煤和瓦斯的深部燃料开采，考虑裂隙介质研究煤的气体流动特性具有现实意义。在实验室中获得了含有不同裂缝网络的煤样。通过工业计算机断层扫描测试对裂缝网络进行定量分类。进行了几次气流测试，并研究了经典渗透率模型对预压裂煤样的适用性。主要结果如下：定义了一个指标来描述裂缝网络的复杂性，裂缝煤样的复杂性指标从0.4变化到0.7。随着复杂度指数的增加，煤层裂隙渗透率呈现幂函数增长。预压裂煤样与未压裂煤样的最大渗透率分别达到300多倍。在瓦斯压力作用下，裂隙煤呈现出5种典型的渗透率演化模式。围压的增加减弱了有效应力对裂缝网络的压缩作用，增加了瓦斯对煤基质的吸附收缩作用的可能性。考虑到预压裂裂缝网络的影响，新的经验渗透率模型可以很好地描述裂缝样品的渗透率演化，符合渗透率回弹和恢复的实验现象。围压的增加减弱了有效应力对裂缝网络的压缩作用，增加了瓦斯对煤基质的吸附收缩作用的可能性。考虑到预压裂裂缝网络的影响，新的经验渗透率模型可以很好地描述裂缝样品的渗透率演化，符合渗透率回弹和恢复的实验现象。围压的增加减弱了有效应力对裂缝网络的压缩作用，增加了瓦斯对煤基质的吸附收缩作用的可能性。考虑到预压裂裂缝网络的影响，新的经验渗透率模型可以很好地描述裂缝样品的渗透率演化，符合渗透率回弹和恢复的实验现象。