Characterization of the Pore Structure of Porous Media Using non-Newtonian Fluids

Abstract

We demonstrate a simple, cheap method for pore size characterization of porous media that generates a distribution of pore radii for improved flow and transport modeling. The new method for pore structure characterization utilizes recent theoretical developments in non-Newtonian fluids. Numerical evaluations and validations with synthetic porous media showed potential for obtaining a distribution of effective pore radii and their contribution to total flow only by complementing water with non-Newtonian fluids in saturated infiltration experiments. To demonstrate this ability on real sands, a series of one-dimensional column experiments was conducted with varying porous medium packings, including Accusands and a polydisperse sand/glass bead mixture. For each packing, distilled water and varying concentrations of guar and xanthan gum were injected over a range of flow rates and pressure gradients. The model-generated pore radii were compared with pore radius distributions measured by X-ray microcomputed tomography (μCT), with results demonstrating good agreement between the model and μCT data. Simulations of saturated water flow and drainage curves using model-generated pore radii compared favorably to experimental data, with errors typically between 2% and 10% for single-phase flow and approaching the error of the μCT measured radius distributions for the drainage curves.