MEASUREMENT OF POROUS-MEDIA COMPONENT CONTENT AND HETEROGENEITY USINGGAMMA-RAY TOMOGRAPHY

Tomographic images of porous media are complex distributions of linear attenuation coefficients that reflect the combined effects of scannin g spatial resolution, photon statistical measurement errors, and true material densities. We address how the true voxel-scale attenuation di stribution and measurement errors are convoluted to yield measured den sity frequency distributions. A deconvolution algorithm is demonstrate d that uses the measured density frequency distributions and known pho ton statistical errors to quantify average cross-section volume conten ts of pure components and a mixed-component phase. The mixed-component phase represents regions where components are intertwined or varied i n spaces smaller than the scanning resolution. This approach is applie d to a complex core of the Culebra Dolomite Member of the Rustler Form ation collected at the Waste Isolation Pilot Plant, near Carlsbad, New Mexico. The methodology provides a quantitative measure of the volume content of gypsum, dolomite, and mixed-components, and heterogeneity in the sample.