Visualization of Two-Fluid-Phase Flow Dynamics Using Micro-models

Microfluidic approaches provide an opportunity to observe phase distributions, interfaces, common curves, and curvatures at high spatial and temporal resolutions in two-fluid-phase porous medium systems. Such observations provide an opportunity to visualize mechanisms, determine closure relations needed for existing and evolving models, and provide a means to validate theoretical predictions. We use a 500-micron cell with a circular solid phase to study two-fluid-phase displacement, including a dense pattern of drainage, imbibition, and scanning curves at very high spatial and temporal distribution. Viscous fingering, Haines jumps, and snap-off processes are visualized. A lattice Boltzmann method (LBM) is used to model the experimental data and shows excellent agreement for equilibrium states and certain aspects of the dynamics. Pressure dynamics, displacement processes, and interface curvature change time scales are shown. The fluid pressure, saturation, curvature, and interfacial area data is used to demonstrate that a unique, non-hysteretic closure relation exists. Further, the data is compared to mechanistic predictions based upon the thermodynamically constrained averaging theory (TCAT), validating key aspects of the theory.