Multi-Scale Image Analysis of Digital Carbonate Rock

Abstract

Summary Three-dimensional (3D) information on rock microstructures is important for a better understanding of physical phenomena and for rock characterization on the micro-scale. Digital rock physics (DRP) can directly image rock microstructures across a continuous range of length scales and can be used to predict rock properties. In most cases, the simulated results from rock images can agree well with their lab measurements. However, some properties, such as the effective elastic moduli, strongly depend on the microstructural details of rock, which can lead to a dissatisfied comparison between numerical simulations and lab measurements. High-resolution images can provide more detailed microstructures of rocks but they may not represent the whole sample as their physical sizes are very small. In addition, some unresolved phases, containing many micro-porosities and cement, may have an impact on the calculation of elastic moduli of digital rocks. In this paper, we use multi-scale CT images of a heterogeneous carbonate rock sample to study its heterogeneity and the impact of unresolved phases on the calculation of rock properties. Besides, we study the upscaling methods for multi-scale image analysis in DRP.