Effect of wettability on flow in porous media

Viscous flow in porous media with different surface wettabilities was experimentally studied to investigate the effect of liquid slip on the flow using the micro-particle image velocimetry (|J,-PIV) technique. A transparent microchannel, made of polydimethylsiloxane (PDMS), with a depth of 100 |J,m was used for flow visualization. The micro porous medium was made of solid cylinders with a diameter of 180 |J,m. The cylinders were arranged in line inside the microchannel. The surface wettability of the microchannel was modified by O2 plasma treatments to prepare both water-wet and oil-wet conditions. Measured velocity profiles were compared with numerical simulations. Both experimental and numerical results showed that the difference in the velocity profiles with the wettabilities was under 2.4 % at the center of the throats. The ratio of absolute permeability under the oilwet condition to the water-wet condition was calculated as 1.2. This study provides the criterion of the slip impacts on the velocity profiles and permeability of single-phase flow in porous media under the oil-wet condition. The results can be used for the verification of data when extending the investigation to two-phase flow for understanding oil displacement behavior.