Wettability stabilizes fluid invasion into porous media via nonlocal, cooperative pore filling

TL;DR

This paper introduces a pore-scale model demonstrating how wettability influences fluid invasion stability in porous media, revealing mechanisms that can optimize applications like hydraulic fracturing and CO2 sequestration.

Contribution

A novel nonlocal pore-scale model incorporating wettability effects and dynamic interface readjustments, advancing understanding of fluid displacement stability in porous media.

Findings

Increased wettability promotes cooperative pore filling and stabilizes invasion.

Higher flow rates suppress wettability effects due to viscous instabilities.

Two dimensionless numbers predict displacement modes based on wettability and flow conditions.

Abstract

We study the impact of the wetting properties on the immiscible displacement of a viscous fluid in disordered porous media. We present a novel pore-scale model that captures wettability and dynamic effects, including the spatiotemporal nonlocality associated with interface readjustments. Our simulations show that increasing the wettability of the invading fluid (the contact angle) promotes cooperative pore filling that stabilizes the invasion, and that this effect is suppressed as the flow rate increases, due to viscous instabilities. We use scaling analysis to derive two dimensionless numbers that predict the mode of displacement. By elucidating the underlying mechanisms, we explain classical yet intriguing experimental observations. These insights could be used to improve technologies such as hydraulic fracturing, CO$_{2}$ geo-sequestration, and microfluidics.