On the preferential flow patterns induced by transverse isotropy and non-Darcy flow in double porosity media
Computer Methods in Applied Mechanics and Engineering, 353:570 - 592, 2019.
Summary
This paper examines fluid transport in deformable materials containing two pore scales with a strong contrast in permeability. Sedimentary rocks motivate the formulation: fluid can move along larger microfractures as well as through much smaller matrix nanopores. Preferred fracture orientations create directional permeability at the larger scale, while the small matrix pores can produce departures from Darcy behavior. A coupled hydromechanical model incorporates both effects by representing the fracture system as transversely isotropic and allowing non-Darcy transport within the matrix. Although shale provides the physical motivation, the model is formulated for a more general class of double-porosity materials with similar transport characteristics. The analysis focuses on how anisotropy and the matrix flow law jointly shape preferential flow patterns, highlighting processes that cannot be captured by a conventional isotropic, single-porosity description.