Generalized network modeling of capillary-dominated two-phase flow

TL;DR

This paper introduces a comprehensive pore-scale network model for simulating capillary-driven two-phase flow in porous media, improving accuracy by detailed discretization and validation against simulations and experiments.

Contribution

It develops a generalized network model with detailed corner discretization for more accurate two-phase flow simulation in porous media.

Findings

Model accurately predicts relative permeability and capillary pressure.

Validation shows good agreement with finite-volume simulations.

Model outperforms conventional pore-network models.

Abstract

We present a generalized network model for simulating capillary-dominated two-phase flow through porous media at the pore scale. Three-dimensional images of the pore space are discretized using a generalized network -- described in a companion paper (https://doi.org/10.1103/PhysRevE.96.013312) -- that comprises pores that are divided into smaller elements called half-throats and subsequently into corners. Half-throats define the connectivity of the network at the coarsest level, connecting each pore to half-throats of its neighboring pores from their narrower ends, while corners define the connectivity of pore crevices. The corners are discretized at different levels for accurate calculation of entry pressures, fluid volumes and flow conductivities that are obtained using direct simulation of flow on the underlying image. This paper discusses the two-phase flow model that is used to compute the averaged flow properties of the generalized network, including relative permeability and capillary pressure. We validate the model using direct finite-volume two-phase flow simulations on synthetic geometries, and then present a comparison of the model predictions with a conventional pore-network model and experimental measurements of relative permeability in the literature.