WBPC2019 Abstract #6:
X-ray computed tomography (CT) scanning is a non-destructive technique that reveals details of 3-dimensional (3D) structures that cannot be identified by visualization or 2-D X-ray radiography. Industrial CT systems offer great versatility and advantages in analyzing large or dense materials with high X-ray attenuation while providing significantly higher spatial and contrast resolution than common medical CT scanners. Geomaterials, particularly petroleum reservoir rocks and mining ores, have become one of many applications of industrial CT systems.
Because the CT imagery represented by grey-level values is closely related to density of scanned objects, it is now possible to distinguish different minerals with sufficient density contrast, e.g., quartz/feldspar from carbonate. With advanced image analysis of the CT scanning imagery, much compositional, structural, and textural information is quantitatively extracted. Such CT volume imagery is a rich dataset that is further processed in dedicated image analysis softwares. High-resolution industrial CT has become an indispensable technique in cracking the code (i.e., digitizing) of a geomaterial without the need for physical cracking.
To demonstrate one specific application, CT scanning was conducted at the Saskatchewan Research Council for reservoir cores across the Viking formation, central-west Saskatchewan. With a history of multiple depositional and erosional events, the Viking formation presents complex lithology and mineralogy across its payzone of less than 10 metres. Classic core characterization techniques such as gamma ray logging, petrographic observation, and X-ray powder diffraction are often limited by measurement accuracy and sampling numbers. CT scanning of full-sized core at a resolution of 90 microns can separate clays (as an entire group rather than individual clay minerals) from the higher-permeability oil-bearing sand zones. This is of vital importance for the Viking production, because the large volume-percentages of water-sensitive clays pose injectivity issues. At spatial resolution of 30 microns for common 1.5-inch-diameter core plugs, features such as small sedimentary structures, natural/induced fractures, and bioturbations can be easily identified. This high-resolution digital core becomes a valuable input for subsequent studies in many areas of geoscience and petroleum engineering.