Comparison of pressure-saturation characteristics derived from computed tomography and lattice Boltzmann simulations

A Shan-Chen-type multiphase lattice Boltzmann (LB) model was applied to observed computed microtomography data from water-air and water-Soltrol displacement experiments in a glass bead porous medium. Analysis of the Bond, Reynolds, and Capillary numbers for these systems showed that capillary forces were dominant removing the need to model viscous, gravitational, and density effects. A numerical parameterization of the LB model yielded lattice surface tension and contact angle, and appropriate pressure boundary conditions. Two scaling relations provided a link between lattice pressure and physical pressure and lattice time and physical time. Results showed that there was a good match between measured and simulated pressure-saturation data for the water-air system, but that there were large differences between the simulations and observations for the water-Soltrol system. The discrepancies for the water-Soltrol system were probably due to inconsistencies between experimental conditions and simulated conditions such as nonzero contact angle in the experiments. Analysis of saturation profiles indicated increasing saturation near the wetting boundary and decreasing saturations near the nonwetting boundary. We attribute these saturation transitions to pore-neck and percolation effects. While computationally intensive, results of this study were very encouraging for the application of LB simulations to microscale interfacial phenomena. Future studies will carry out a further validation in terms of interfacial areas, contact lines, and fluid distributions.