Experimental Study of Diffusive Tortuosity of Liquid-Saturated Consolidated Porous Media

Abstract

Diffusive tortuosity factor is one of the key parameters in modeling solute diffusion in liquid-saturated porous media. However, the determination of diffusive tortuosity factor has to involve a diffusion process in liquid-saturated porous media, which was usually found complicated in laboratories. The incorrect use of diffusive tortuosity factor may cause significant errors in certain circumstances. This paper presents a method to evaluate the diffusive tortuosity factors for liquid-saturated consolidated porous media, i.e., sandstones, which are the typical porous media commonly encountered in contaminant transport in underground water and gas migration in liquid-saturated reservoirs. The proposed method applies two specific experiments to determine the diffusion coefficient in bulk liquid phase and the effective diffusion coefficient in liquid-saturated porous media, respectively. Diffusive tortuosity factor of the porous media is obtained by comparing the effective diffusion coefficient in porous media to the diffusion coefficient in bulk liquid. This study provides a procedure to evaluate the diffusive tortuosity factor for consolidated porous media and also the measured values of diffusive tortuosity factors for selected sandstone samples which can be used as input data for further studies. Another application of the proposed method is to determine the diffusion coefficient in bulk liquid phase for CO2 from the measured effective diffusion coefficients in porous media.