Simulating volume-controlled invasion of a non-wetting fluid in volumetric images using basic image processing tools

TL;DR

This paper introduces a volume-controlled invasion algorithm for simulating non-wetting fluid flow in voxel images, offering more precise saturation control and trapping prediction compared to pressure-based methods, validated against traditional approaches and lattice Boltzmann simulations.

Contribution

The paper presents a novel volume-based invasion algorithm that improves saturation control and trapping prediction, surpassing traditional morphological methods and matching lattice Boltzmann results in efficiency.

Findings

Accurate prediction of trapping phenomena.

Capillary pressure curves with characteristic jumps.

Comparable results to lattice Boltzmann simulations in less time.

Abstract

A new algorithm is presented for simulating volume-controlled invasion of a non-wetting phase into voxel images. This method is complementary to the traditional morphological image opening method which mimics pressure-based invasion. A key advantage of the volume-based approach is that all saturations between 0 and 1 can obtained rather than the irregularly and widely spaced saturation steps obtained by pressure-based methods. Because of the incremental increases in saturation, it becomes possible to correctly predict defending phase trapping, which is not the case when pressure-based steps are applied. The algorithm is validated against morphological image opening and obtains near perfect agreement at equal saturations as expected from theory. It is also demonstrated that a volume-controlled capillary pressure curve can be obtained that displays the characteristic jumps in capillary pressure, and moreover, the envelop of peak pressures yields the pressure-based capillary pressure obtained by morphological opening, so in fact the results of the proposed algorithm are a superset of the morphological approach. Finally, results are compared to multiphase lattice Boltzmann and qualitatively similar results were achieved in substantially less time. The lattice Boltzmann method is more flexible in terms of variable contact angle and inclusion of viscous effects, but for quasi-static volume-based injection of a non-wetting fluid, the proposed method is viable alternative.