Dynamics of diffusive and convective transport in porous media: A fractal analysis of 3-D images obtained by laser technology

It was observed through 3-D images obtained from the experiments that the width (area) of the solvent swept region and fingering depended on the density of the solvent and the speed of the process was higher in the high permeability porous media (4 mm glass beads). Wider fingers and swept areas were observed for less viscous solvent. Solvents 1 and 2 slowly mixed and rose to the top of the model filling most of the pores in the model, and then diffused into the unswept region. Solvent 3 reached the top of the model in an extremely short time along the boundary with thin fingering and displaces downward afterwards. The frontal progresses of solvent-oil interfaces (mixing zone) were analyzed quantitatively through the change of the fractal dimension during the process. The fractal dimension increased before the solvent reached at the top of the model. For solvents 1 and 2, the fractal dimension decreased afterward. For solvent 3, the value declined rapidly because the solvent took time to spread along the top of the model due to its extremely low viscosity and density.