Resolution and Limitations of X-Ray Micro-CT with Applications to Sandstones and Limestones

• Published in: Transport in porous media 2019-08, Vol.129 (1), p.413-425
• Main Authors: Elkhoury, Jean E., Shankar, Raji, Ramakrishnan, T. S.
• Format: Article
• Language: English
• Subjects: Algorithms; Civil Engineering; Classical and Continuum Physics; Computed tomography; Earth and Environmental Science; Earth Sciences; Failure analysis; Geotechnical Engineering & Applied Earth Sciences; Hydrogeology; Hydrology/Water Resources; Image resolution; Image segmentation; Industrial Chemistry/Chemical Engineering; Limestone; Medical imaging; Medical materials; Pore size; Porosity; Sandstone; Scanning; Tomography; Topology; X ray absorption; X ray microtomography
• ISSN: 0169-3913; 1573-1634
• DOI: 10.1007/s11242-019-01275-1

X-ray microtomography ( μ CT ) scanning provides high-resolution images in applications ranging from medical to material sciences and failure analysis. In general, CT scanning relies on X-ray absorption to produce a 3D computed image of the material. In Earth Sciences, μ CT scans are used to characterize porosity and pore size, shape and topology of rock samples. For sufficiently large pore systems, the resulting segmented images may be used for quantitative transport calculations. In this note, we infer the limitations of μ CT images of rock samples, caused by attainable resolution for a representative sample size. To this end, (1) we perform a systematic analysis with the aid of a resolution chart, (2) we present example scans of an Indiana limestone and a Berea sandstone mini-cores, and (3) we process and analyze the images to extract pore structures using different segmentation algorithms. Porosity estimates inferred from μ CT images tend to be lower than bulk measurements.