Trapping and Mobilization of Residual Fluid During Capillary Desaturation in Porous Media

TL;DR

This paper investigates the dynamics of residual fluid trapping and mobilization in porous media during two-phase flow, revealing that a new macroscopic capillary number clarifies discrepancies between experimental data and theoretical predictions.

Contribution

It introduces a novel macroscopic capillary number that resolves inconsistencies in capillary desaturation curves for discontinuous mode displacement.

Findings

Replotting data against the new capillary number aligns experiments with theory.

Discontinuous mode displacement behavior is better explained with the new macroscopic capillary number.

The study challenges existing interpretations of capillary number effects in porous media flow.

Abstract

We discuss the problem of trapping and mobilization of nonwetting fluids during immiscible two phase displacement processes in porous media. Capillary desaturation curves give residual saturations as a function of capillary number. Interpreting capillary numbers as the ratio of viscous to capillary forces the breakpoint in experimental curves contradicts the theoretically predicted force balance. We show that replotting the data against a novel macroscopic capillary number resolves the problem for discontinuous mode displacement.