The permeability of shale controls gas transport in shale gas reservoirs. The shale has a complex pore structure at the nanoscale and its permeability is affected by multiple transport and action mechanisms. In this study, a 3D fractal model for predicting the apparent gas permeability of shale matrix is presented, accounting for the effects of the transport mechanisms (bulk gas transport and adsorption gas diffusion) and action mechanisms (gas adsorption, real gas properties, water film, stress dependence, and total organic carbon (TOC) content). The proposed model is validated with the published experimental data. A series of sensitivity analyses are performed to investigate the influence of fractal characteristics and action mechanisms on the apparent permeability caused by each transport mechanism. The results show that the real gas properties, water film, and stress dependence cause different effects on the total apparent permeability of shale under different fractal characteristics. The maximum pore diameter is inversely proportional to the effects of these action mechanisms, and the porosity is positively proportional to the effects of real gas properties and water film but inversely proportional to the effects of stress dependence. An increase in TOC content can cause an improvement in the total apparent permeability. Furthermore, the effects of action mechanisms on the apparent permeability caused by different transport mechanisms are differently affected by the fractal characteristics. Changes in fractal characteristics mainly affect the apparent permeability caused by slip flow in the real gas effect, slip flow and Knudsen diffusion in the water film effect, and all transport mechanisms in the stress dependence effect.

页岩的渗透率控制着页岩气藏中的气体输运。页岩具有复杂的纳米级孔隙结构，其渗透率受到多种输运和作用机制的影响。在这项研究中，提出了一个用于预测页岩基质表观气体渗透率的 3D 分形模型，该模型考虑了传输机制（散装气体传输和吸附气体扩散）和作用机制（气体吸附、真实气体性质、水膜）的影响。 、应力依赖性和总有机碳 (TOC) 含量）。所提出的模型通过已发表的实验数据进行了验证。通过一系列敏感性分析来研究分形特征和作用机制对每种输运机制引起的表观渗透率的影响。结果表明，不同分形特征下，真实气体性质、水膜和应力依赖性对页岩总表观渗透率产生不同的影响。最大孔径与这些作用机制的影响成反比，孔隙率与真实气体性质和水膜的影响成正比，但与应力依赖性的影响成反比。 TOC含量的增加可以导致总表观渗透率的改善。此外，不同输运机制引起的作用机制对表观渗透率的影响也受到分形特征的不同影响。分形特征的变化主要影响真实气体效应中滑流引起的表观渗透率、水膜效应中滑流和克努森扩散以及应力依赖效应中所有输运机制。