18 X-Ray Computed Tomography for Measurement of Fluid Transport Properties Available to Purchase

Estimation of contaminant transport parameters in porous media is often constrained by the inability to measure pore-scale phenomena. Use of x-ray computed tomography (CT) may provide a tool to measure fluid transport at the pore-scale to facilitate estimation of transport parameters. The objective of this study was to use x-ray CT methods to measure transport of an iodide tracer in porous media and estimate porosity, solute pore-water velocity and solute dispersivity. CT-measured breakthrough curve experiments were conducted in columns of glass beads ranging from 1.4 to 8.0 mm in diameter with four sizes. Iodide breakthrough experiments were conducted using a medical CT scanner with a voxel size 0.5 by 0.5 mm by 2.0 mm thick. Based on the breakthrough curve for each pixel, the porosity, solute pore-water velocity and solute dispersivity distributions were determined. Frequency distributions of porosity within the core samples, excluding values equal to zero and one, were found to be uniform. The frequencies of porosity equal to zero and one increased as the log of glass bead diameter increased. Dispersivity frequency distributions for three glass bead sizes needed transformations using a 0.25 power to normalize the distributions. The study illustrates that this method of analysis is potentially useful for evaluating solute transport on a macropore-scale for porous materials.