A Microfluidic Study of Immiscible Drainage Two-Phase Flow Regimes in Porous Media

The motivation for this work is an improved characterization of flow regimes for two immiscible phases in porous media. A microfluidic device featuring a water-wet porous medium that is based on a two-dimensional representation of a Berea sandstone is coupled with a high-resolution camera that allows the visualization of the entire domain, while being able to resolve features as small as 10 μm. Drainage flow experiments are conducted across a range of capillary numbers of 1E−4 to 9E−8. The viscosity ratios, defined as the viscosity of the resident fluid to that of the invading fluid, range from 1E−4 to 13.6E3. The findings are mapped on a two-dimensional parameter space (viscosity ratio and capillary number), and stability diagrams proposed in the literature are superimposed for comparison. Results suggest that the transition regime may occupy a much larger region of the flow regime diagram than is suggested in recent literature.