Electroosmotic Coupling in Porous Media, a New Model Based on a Fractal Upscaling Procedure

Abstract

Electrokinetic and electroosmotic couplings can play important roles in water and ions transport in charged porous media. Electroosmosis is the phenomena explaining the water movement in a porous medium subjected to an electrical field. In this work, a new model is obtained through a new up-scaling procedure, considering the porous medium as a bundle of tortuous capillaries of fractal nature. From the model, the expressions for the electroosmosis pressure coefficient, the relative electroosmosis pressure coefficient, the maximum back pressure, the maximum flow rate, the flow rate-applied back pressure relation and the product of the permeability and formation factor of porous media are also obtained. The sensitivity of the relative electroosmosis pressure coefficient is then analyzed and explained. The model predictions are then successfully compared with published datasets. Additionally, we deduce an expression for the relative streaming potential coefficient and then compare it with a previously published model and experimental data from a dolomite rock sample. We find a good agreement between those models and experimental data, opening up new perspectives to model electroosmotic phenomena in porous media saturated with various fluids.