Multiscale Dynamics of Colloidal Particle Transport in Porous Media*

Colloidal particle transport in porous media is commonly encountered in various industrial activities. In particular, there is significant interest to improve oil recovery or aquifer remediation by subsurface injection of surface-active particles. The transport of particles in such systems is complex due to the interplay of particle adsorption, surface erosion, and pore-space advection. Here, we developed a model transparent porous medium that we can image in 3D using confocal microscopy. Through this medium, we observe, for the first time, the interchange between adsorption and erosion events. With these observations, along with a statistical nonlinear model and a continuum model, we demonstrate how different conditions dictate which transport mechanism is dominant. These findings ultimately show how the pore-scale transport dynamics can be controlled to achieve macroscopic aims in oil recovery or aquifer remediation.