Stabilizing Fluid-Fluid Displacements in Porous Media Through Wettability Alteration

Abstract

The authors experimentally identify the stabilizing effect of wettability in a porous matrix during the immiscible displacement of a viscous fluid (such as oil) by a much less viscous one (such as water). By altering the wettability of the medium from drainage (contact angle $\ensuremath{\theta}$ = 5\ifmmode^\circ\else\textdegree\fi{}) to imbibition ($\ensuremath{\theta}$ = 120\ifmmode^\circ\else\textdegree\fi{}), the classical viscous-fingering instability is stabilized and even completely suppressed at low capillary numbers (i.e. low injection rates), making the invading fluid better at pushing out the defending fluid. These results have implications for improving oil recovery, CO${}_{2}$ sequestration, and fuel-cell design.