Correlating Wettability Percolation with Impedance Spectroscopy of Wet Granular Systems

A better understanding of the wettability and percolation of granular systems has significant potential implications for the improvement of oil recovery methods. In this paper, we seek to correlate the dielectric response of various samples with the content and connectivity of their composition. To do this, we prepare mixtures of hydrophobic and hydrophilic beads at ratios above and below their respective percolation thresholds and measure their impedance during water adsorption using Electrochemical Impedance Spectroscopy (EIS). From this data, we compute and log-scale plot the dielectric constant against conductivity as an implicit function of time or pressure. We then demonstrate a power law relationship between these quantities using linear regressions. Using these regression slopes, we form the index of percolation wettability, a metric for determining the content and connectivity of hydrophobic and hydrophilic species in a sample. Our results confirm that the dielectric-conductance correlation exists, varies directly with hydrophilic content, and forms distinct regimes based on the percolation of the hydrophobic and hydrophilic species.