From mixing to displacement of miscible phases in porous media: The role of heterogeneity and inlet pressure

TL;DR

This paper investigates how heterogeneity and inlet pressure influence mixing and displacement patterns in miscible flows through porous media, revealing transitions from uniform to fingering patterns and proposing a non-dimensional modeling approach.

Contribution

It introduces a quantitative framework linking pore-scale patterns to Darcy-scale observations, emphasizing the roles of heterogeneity and inlet pressure in miscible phase displacement.

Findings

Inlet pressure and heterogeneity significantly affect flow patterns.

Transition from uniform to fingering patterns is quantified by a modified Sherwood number.

Higher heterogeneity and pressure broaden velocity distributions, promoting fingering.

Abstract

Miscible multiphase flow in porous media is a key phenomenon in various industrial and natural processes, such as hydrogen storage and geological carbon sequestration. However, the parameters controlling the patterns of displacement and mixing in these flows are not completely resolved. This study delves into the effects of heterogeneity and inlet pressure on mixing and displacement patterns of low-viscosity miscible phase invasion into a high-viscosity resident phase, that is saturating a porous medium. The findings highlight the substantial influence of inlet pressures and heterogeneity levels in transitioning from uniform to fingering patterns at the pore scale. These phenomena are detectable at the Darcy scale, and their transition from a uniform front to finger formation is effectively quantified through a modified Sherwood number. This quantification links microscale patterns to physical properties like velocity distribution, diffusion, and viscosity contrasts. Additionally, the study employs breakthrough curve (BTC) analysis to illustrate the role of higher heterogeneity and inlet pressure in broadening the fluid velocity distribution, leading to the fingering pattern. These research insights provide a non-dimensional approach for future models of miscible phase flow in porous media, linking pore-scale dynamics with macro-scale Darcy-scale observations