Hydraulic fracturing causes the fracture zone phenomenon in a coal seam. The effectiveness of coalbed methane (CBM) extraction is determined by the seepage characteristics of various fracture zones under gas pressure attenuation by gas extraction in coal seams. Based on this, this paper developed a zonal seepage test device for hydraulic fracturing coal, designed a series and parallel test method for intact coal sample, microfracture coal sample and penetration fracture coal sample. This method can simulate the migration process of CBM in different disturbance areas near the wellbore in the initial stage of hydraulic fracturing (transverse seepage) and the migration process of CBM from the matrix to the wellbore in the later stage (longitudinal seepage). On this basis, the seepage characteristics of the complex zonal phenomenon produced by hydraulic fracturing under the condition of gas pressure attenuation were studied. A series and parallel permeability model combining Klinkenberg effect, expansion effect and effective stress was established. This model can well describe the series and parallel permeability variation law with gas pressure. It indicated that the adsorption expansion effect and effective stress have an impact on the coal matrix during the longitudinal seepage process, which restricts the seepage of both natural and artificial fractures. Artificial fractures are less impacted by the expansion effect and effective stress during the transverse seepage process, which makes them the primary seepage channel. Combined with the extraction data and the permeability model, the gas production trend in the Qinshui Basin is divided into two stages: transverse seepage dominant stage and longitudinal seepage dominant stage.

水力压裂导致煤层中出现破裂带现象。煤层气抽采效果取决于煤层瓦斯抽采瓦斯压力衰减作用下各裂隙带的渗流特征。在此基础上，研制了水力压裂煤分区渗流试验装置，设计了完整煤样、微裂隙煤样和渗透裂隙煤样的串并联试验方法。该方法可以模拟水力压裂初期煤层气在井筒附近不同扰动区域的运移过程（横向渗流）和后期煤层气从基质向井筒的运移过程（纵向渗流）。在此基础上，研究了瓦斯压力衰减条件下水力压裂产生的复杂层带现象的渗流特征。建立了结合克林肯伯格效应、膨胀效应和有效应力的串并联渗透率模型。该模型能够很好地描述渗透率随气体压力的串并联变化规律。表明纵向渗流过程中吸附膨胀效应和有效应力对煤基质产生影响，对天然裂缝和人工裂缝的渗流均具有制约作用。人工裂缝在横向渗流过程中受膨胀效应和有效应力的影响较小，是主要渗流通道。结合提取资料和渗透率模型，将沁水盆地产气趋势划分为横向渗流主导阶段和纵向渗流主导阶段两个阶段。