Single- and two-phase flow in microfluidic porous media analogs based on Voronoi tessellation

Journal Article · Sun Jan 01 00:00:00 EST 2012 · Lab on a Chip

DOI:https://doi.org/10.1039/c1lc20838a· OSTI ID:1081886

Wu, Mengjie ^[1]; Xiao, Feng ^[1]; Johnson-Paben, Rebecca ^[1]; Retterer, Scott T ^[2]; Yin, Xiaolong ^[1]; Neeves, Keith B ^[2]

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1. Colorado School of Mines, Golden
2. ORNL

The objective of this study was to create a microfluidic model of complex porous media for studying single and multiphase flows. Most experimental porous media models consist of periodic geometries that lend themselves to comparison with well-developed theoretical predictions. However, most real porous media such as geological formations and biological tissues contain a degree of randomness and complexity that is not adequately represented in periodic geometries. To design an experimental tool to study these complex geometries, we created microfluidic models of random homogeneous and heterogeneous networks based on Voronoi tessellations. These networks consisted of approximately 600 grains separated by a highly connected network of channels with an overall porosity of 0.11 0.20. We found that introducing heterogeneities in the form of large cavities within the network changed the permeability in a way that cannot be predicted by the classical porosity-permeability relationship known as the Kozeny equation. The values of permeability found in experiments were in excellent agreement with those calculated from three-dimensional lattice Boltzmann simulations. In two-phase flow experiments of oil displacement with water we found that the surface energy of channel walls determined the pattern of water invasion, while the network topology determined the residual oil saturation. These results suggest that complex network topologies lead to fluid flow behavior that is difficult to predict based solely on porosity. The microfluidic models developed in this study using a novel geometry generation algorithm based on Voronoi tessellation are a new experimental tool for studying fluid and solute transport problems within complex porous media.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1081886
• Journal Information: Lab on a Chip, Vol. 12, Issue 2; ISSN 1473--0197
• Country of Publication: United States
• Language: English