Extended Dual Porosity/Dual Permeability Model for Fluid Flow in Reservoirs with Multiscale Complex Fracture Networks

Abstract Accurately modeling fluid flow through naturally fractured reservoirs is essential for developing effective resource extraction strategies and subsurface energy applications. Although discrete fracture models (DFM) provide high-fidelity representations of fracture geometry, their substantial computational cost and complex meshing requirements lead to significant challenges, particularly for large-scale and highly fractured systems. Implicit fracture models offer a more efficient alternative for representing complex, well-connected fracture networks. This work introduces an extended dual porosity/dual permeability (xDPDP) formulation for simulating single-phase flow in formations containing dominant and interconnected fracture systems. The method implicitly represents fractures by combining homogenized permeability with a modified shape factor derived from the geometric and spatial characteristics of the network. This approach enables the use of regular, nonconforming meshes, significantly reducing meshing complexity while preserving the influence of multiple fracture types. A series of numerical experiments demonstrates the accuracy and efficiency of the xDPDP formulation in simulating fluid flow in highly fractured reservoir cells. Results show excellent agreement with DFM in predicting pressure fields and flow dynamics across scenarios involving multiscale fracture configurations. A parametric study further highlights the method’s robustness in capturing the effects of fracture geometry and connectivity. Overall, the xDPDP formulation provides a scalable, computationally efficient alternative for modeling fluid flow in highly fractured reservoirs.