PNNL

Abstract

This paper presents a multi-scale approach for modeling the transport of species in fractured porous media. The multi-scale approach consists of a hybrid model and a pore-scale model that is used to parameterize the hybrid model. The hybrid model explicitly models the advection and diffusion of species in the fracture and treats the porous matrix as a continuum with effective transport properties. The pore-scale model is used to calculate the effective transport properties of the hybrid model. This approach negates the need to calibrate the hybrid model against experimental data, which is common for continuum-scale models of porous media, and allows an arbitrary microstructure to be considered. The paper presents the multi-scale modeling approach along with the details of the hybrid and pore-scale models. Validation of the model is also presented along with several case studies investigating the applicability of the multi-scale modeling approach to different geometries and transport conditions. The case studies show that the multi-scale modeling approach is accurate for various fracture geometries given that the matrix porosity is sufficiently small. The accuracy of the hybrid model decreases with increasing porosity of the matrix.