Pore-scale heterogeneity, flow channeling and permeability: Network simulation and comparison to experimental data

The flow and transport properties of rocks depend on the statically geometry and topology of the pore space, which can be viewed as a complex network, as well as the characteristics of dynamic fluid flow pathways. The pore-scale heterogeneity (i.e., pore connectivity and pore-size distribution) generates the flow channeling, which can be quantified by the critical radius rc, hydraulic tortuosity τ, and the ratio of effective and non-effective porosity. The rc is defined as the lowest radius in the pathway of flow channeling. The tortuosity τ of the flow channeling can be determined by the Dijkstra algorithm. The “universality” of rc, τ, and the factor σr/z of pore-scale heterogeneity were verified based on network simulations. Since both of the homogeneous and heterogeneous rocks can be reduced as the equivalent channel model (ECM), the new permeability model can be proposed based on the definition of rc. The proposed permeability model is satisfactorily testified against network simulation results, and the published experimental datasets of the different rocks in the literature, including natural and tight sandstone. •The flow channeling are quantified by the critical radius, hydraulic tortuosity.•The critical radius is the lowest radius in the path of flow channeling.•An integrated “universal” factor of pore-scale heterogeneity was introduced.•A new permeability model was proposed by analysis of the flow channeling.