(540a) Impact of Pore Scale Structure and Displacement Mechanisms on Multiphase Flow Modeling In Porous Media: A Perspective and Payatakes' Contributions

Transport phenomena in porous media are encountered in many situations of practical and scientific interest. From the natural porous media, such as soils and water or hydrocarbon reservoirs, to the artificial ones, such as filters, fuel cells, catalysts, concrete etc. determination of the transport properties remains a challenging issue on which work scientists and engineers targeting very different applications.

Related to the problems of natural resources and environment, the description of the transport of fluids in geological formations relies upon advances on the characterization and modeling of natural systems in a large spectrum of time and length scales. The complexity of transport in these systems is due to the complex geological structure and the multiscale heterogeneities as well as to the dynamics of the multiphase fluid displacement and its coupling with mechanical, thermal, chemical and biological processes.

Information on the pore space geometry and topology and on the mechanisms of fluid displacement permits to gain insight into the physics of flow in porous media and to propose relevant modeling approaches. Experiments in 2D micromodels bring information on the fluid interface motion in model systems, while advances in microfluidics extended the observations to the micron scale. In 3D, sophisticated imaging techniques (microtomograph, synchrotron) allowed non-intrusive high resolution observations in real porous media below the micron scale. The FIB (Focused Ion Beam) technique combined to 3D reconstruction of the pore space is called to bring answers in the nanometer scale, which is relevant when studying the sealing capacity of the cap rocks in CO2 storage or the recovery of unconventional hydrocarbon reserves (tight gas, shale gas).

Observation and experimental study have to be intimately linked to pertinent theoretical modeling taking into account the relevant physics of the studied phenomena at the right scale. Advances in molecular dynamics, lattice-Boltzmann or pore-network modeling methods combined to upscaling considerations permit to simulate complex flow regimes and to run laboratory and numerical experiments on comparable sample volumes, which is absolutely necessary for model validation.

Some of the most important contributions in this area have been presented by A.C. Payatakes and his coworkers. His pioneering work goes from the pore structure recognition and characterization to the modeling and simulation of particulate flows in porous media and to the complex multiphase flows including simultaneously connected fluid motion, ganglia dynamics and drop traffic flow. In the frontiers between academic and applied research, Prof. Payatakes' outstanding work is characterized by the combination of the experimental observation and the theoretical analysis at different scales, emphasizing the importance of the physical meaning of the average macroscopic properties and their link to the pore scale phenomena and mechanisms.