Pore-Scale Flow Characterization of Polymer Solutions in Microfluidic Porous Media

TL;DR

This paper uses microfluidic tools to investigate the complex pore-scale flow behavior of polymer solutions in porous media, revealing how flow dynamics and polymer conformations influence fluid recovery processes.

Contribution

It introduces microfluidic methods to analyze polymer solution flow at high Weissenberg numbers and low Reynolds numbers in porous structures, advancing understanding of non-Newtonian flow physics.

Findings

Flow behavior depends on pore geometry and solution properties.

Polymer elasticity causes flow instabilities and fluctuations.

Insights inform enhanced oil recovery and groundwater remediation.

Abstract

Polymer solutions are frequently used in enhanced oil recovery and groundwater remediation to improve the recovery of trapped non-aqueous fluids. However, applications are limited by an incomplete understanding of the flow in porous media. The tortuous pore structure imposes both shear and extension, which elongates polymers; moreover, the flow is often at large Weissenberg numbers Wi at which polymer elasticity in turn strongly alters the flow. This dynamic elongation can even produce flow instabilities with strong spatial and temporal fluctuations despite the low Reynolds number Re. Unfortunately, macroscopic approaches are limited in their ability to characterize the pore-scale flow. Thus, understanding how polymer conformations, flow dynamics, and pore geometry together determine these non-trivial flow patterns and impact macroscopic transport remains an outstanding challenge. Here, we describe how microfluidic tools can shed light on the physics underlying the flow of polymer solutions in porous media at high Wi and low Re. Specifically, microfluidic studies elucidate how steady and unsteady flow behavior depends on pore geometry and solution properties, and how polymer-induced effects impact non-aqueous fluid recovery. This work provides new insights for polymer dynamics, non-Newtonian fluid mechanics, and applications such as enhanced oil recovery and groundwater remediation.