| This thesis investigated experimentally the diffusion properties of geologic media. A gamma-radiation transmission device was developed and optimized, to measure, as a function of time, the spatial distribution of the concentration of a potassium iodide (KI) tracer as it diffuses in the pore space of sedimentary rocks. The design of the device was optimized for samples of 25 mm in thickness, to provide a spatial resolution of 1 mm 2, and to allow the scanning of samples 80 mm x 40 mm in frontal area, with an acquisition time of one-second per point.;Experimental measurements were conducted on samples of dolomite and sandstone from cores obtained from Guelph, Ontario and Moncton, New Brunswick. The spatial distribution of diffusion-accessible porosity, &phis;d, was calculated from the acquired dry and KI-saturated scans. Relative concentration profiles for KI tracer were determined by calibration, and the pore diffusion coefficient, Dp, for each sample was calculated by fitting a one-dimensional analytical solution to the experimental data. Results indicated that one of the dolomite samples and a sandstone rock sample displayed near uniform Dp values. A second dolomite sample was found to exhibit variability in Dp values, which was attributed to its porosity heterogeneity. The results of this work showed that the developed radiation device was capable of providing spatial porosity and tracer concentration information that is useful in characterizing the transport of solute in geological media. |
