On the Interest of Bulk Conductivity Measurements for Hydraulic Dispersivity Estimation from Miscible Displacement Experiments in Rock Samples

Abstract

The determination of the hydraulic dispersivity and effective fraction of porous medium contributing to transport on soil and rock sample in the laboratory is important to understand and model the evolution of miscible contaminant plumes in groundwater. Classical methods are based on the interpretation of the breakthrough curve, i.e., the evolution of the concentration in contaminant at the downstream end-face of a sample into which a front of contaminant is advected. Here we present an experimental device aimed at performing such measurements, but also allowing the bulk electrical conductivity of the sample to be measured. We show that the dispersivity and effective fraction can be inferred from this electrical measurement, and that the combined use of both out-flowing fluid conductivity and bulk conductivity allows the incertitude on the dispersivity and effective fraction to be significantly enhanced.