Wettability and Microfluidics

Microfluidics provides a useful platform to explore the physics of multiphase flow in porous media. Here, we present the results of fluid-fluid displacement experiments in patterned microfluidic chips, designed to improve our understanding of the impact of wettability. Some observations are well known, but others are surprising and point to displacement regimes that need to be better understood. In an effort to rationalize the observations, we have developed a pore-network modeling approach that explicitly accounts for dynamics of pore-scale displacements and is applicable to the entire range of wetting conditions. In particular, we will show recent experimental and modeling results on: (1) Extending Lenormand's diagram to account for all wettability characteristics; (2) Drainage and imbibition in a microfluidic fracture; and (3) Post-breakthrough behavior of immiscible fluid-fluid displacement.