A continuum voxel approach to model flow in 3D fault networks: A new way to obtain up-scaled hydraulic conductivity tensors of grid cells

• An accurate mapping of discrete fracture networks onto a regular mesh is obtained.
• A full hydraulic conductivity tensor in each mesh is needed to model fracture fluxes.
• Hydraulic properties preserve continuity of fluxes between neighbouring meshes.
• Various hydraulic behaviour at fracture intersections can be modelled.

SummaryModelling transfers in fractured media remains a challenging task due to the complexity of the system geometry, high contrasts and large uncertainties on flow and transport properties. In the literature, fractures are classically modelled by equivalent properties or are explicitly represented. The new Fracture Continuum Voxel Approach (FCVA), is a continuum approach partly able to represent fracture as discrete objects; the geometry of each fracture is represented on a regular meshing associated with a heterogeneous field of equivalent flow properties. The mesh-identification approach is presented for a regular grid. The derivation of equivalent voxel parameters is developed for flow simulated with a Mixed Hybrid Finite Element (MHFE) scheme. The FCVA is finally validated and qualified against some reference cases. The resulting method investigates multi-scaled fracture networks: a small scale homogenised by classical methods and large discrete objects as that handled in the present work.