A brief introduction to the use of X-ray computed tomography (CT) for analysis of natural deformation structures in reservoir rocks

Abstract

X-ray computed tomography (CT) is frequently used for non-destructive imaging and analysis of internal features in rock samples. In this paper we review the method for analysis of subseismic deformation structures in reservoir rocks, and provide some examples of different types of structures. Both medical CT and high-resolution µCT have great potential for identification of small-scale deformation structures in reservoir rocks and samples from outcrop analogues. The CT imaging techniques provide 3D data that are used in combination with 2D information from core or outcrop, thin-section and scanning electron microscopy (SEM). CT and µCT are used for quantitative and qualitative analysis of individual fractures and fracture networks, and for imaging and analysis of internal heterogeneities of fault rocks and deformation bands. The benefit of CT is that 3D properties (e.g. structure size, connectivity and variation in aperture) are actually characterized in 3D, contrary to traditional 2D methods using core surface, thin-section and outcrop. Limitations and uncertainties arise from artefacts during acquisition and processing, scale of observation and resolution, and manual steps involved in the segmentation of the CT volume. Increased availability of medical CT and µCT scanners and improved resolution should in the future lead to improved description and modelling of small-scale reservoir structures.