Abstract Currently, hydraulic slotted borehole technology for strengthening gas drainage is one of the main measures to control gas disasters in deep mines. In this paper, to analyze the evolution of gas flow field around the hydraulic slotted borehole, the borehole gas drainage was simulated based on the anisotropy of coal structure and the established multi-field (namely, coal deformation field, diffusion field and seepage field) coupling model. Then, the influences of characteristic parameters, including, initial diffusion coefficient, diffusion attenuation coefficient, initial gas pressure and initial permeability, on the gas production rate and reservoir parameters of hydraulic slotted borehole gas drainage were analyzed. Finally, the results were verified by comparing the model simulation with field tests in Yangliu Mine. The results show that the anisotropy of coal affects the effect of borehole gas drainage. The initial diffusion coefficient D 0 and the diffusion attenuation coefficient λ have opposite effects on key parameters of coal. With a larger D 0 , it is easier for gas in matrix pores to diffuse into the fracture system, and accordingly the gas production rate and relative permeability grow. A larger λ makes it harder for gas in matrix pores to diffuse into fractures, thus decreasing the gas production rate and relative permeability. The initial gas pressure p m0 and the initial permeability k fx0 and k fy0 exert the same effect on the key parameters of coal. The larger their values are, the more easily the gas in fractures can be extracted under the same negative pressure of drainage, which contributes to the diffusion of gas from the matrix into the fracture system under the action of pressure difference. Through combining actual monitoring results of 3# and 4# drilling fields in Yangliu Mine and the results of numerical simulation, it is acquired that the gas production rate measured in situ coincides with the rate simulated by the model, verifying the feasibility and engineering applicability of the model.

中文翻译：

---

各向异性煤中水力开缝钻孔周围气体流场演化

摘要 目前，水力开槽加强瓦斯抽采技术是控制深部瓦斯灾害的主要措施之一。本文为分析水力开槽钻孔周围瓦斯流场的演化，基于煤结构的各向异性和建立的多场（即煤变形场、扩散场和渗流场）模拟钻孔瓦斯抽采。耦合模型。然后，分析了初始扩散系数、扩散衰减系数、初始瓦斯压力和初始渗透率等特征参数对水力开槽钻孔瓦斯抽采产气率和储层参数的影响。最后，通过模型模拟与杨柳矿现场试验的对比验证了研究结果。结果表明，煤的各向异性影响了钻孔瓦斯抽采的效果。初始扩散系数D 0 和扩散衰减系数λ 对煤的关键参数具有相反的影响。D 0 越大，基质孔隙中的气体越容易扩散到裂缝系统中，因此产气速率和相对渗透率增大。较大的 λ 使基质孔隙中的气体更难扩散到裂缝中，从而降低产气速率和相对渗透率。初始瓦斯压力 p m0 和初始渗透率 k fx0 和 k fy0 对煤的关键参数具有相同的影响。它们的值越大，在相同的排水负压下越容易抽取裂缝中的气体，在压力差的作用下，有利于气体从基体扩散到裂缝系统中。结合杨柳矿3#、4#钻井现场实际监测结果和数值模拟结果，现场测得的产气量与模型模拟的产气量吻合，验证了该方法的可行性和工程适用性。该模型。