Digital image analysis of stress-dependent granular compaction and its impact on multiphase fluid distributions

Abstract:

Pore-scale investigation of multiphase fluid behavior in porous media is useful for obtaining quantitative information about relationships between micro-pore structures and multiphase flow and their impact on fluid distribution under different conditions. Recent advances in imaging techniques such as X-ray computed microtomography (microCT) allows us to examine three-dimensional (3D) micro-pore structures and multiphase distribution. However, many previous experiments with microCT imaging have been largely limited to static conditions. In this work, we focus on stress-dependent granular compaction under flowing conditions and its impact on displacement mechanisms and multiphase distribution under multiple drainage and imbibition cycles. A stack of 3D images were obtained with microCT to examine pore structures and fluid distribution under each cycle. Advanced imaging processing techniques were employed to improve the quality of multiphase segmentations. Key characteristics of pore structures and fluid distribution include porosity, permeability, specific surface area, interfacial area, Euler characteristic, and phase saturation. Additional lattice-Boltzmann simulations are used to investigate how inter-granular compaction mechanisms may affect fluid displacement and residual trapping at the pore-scale. This will improve our understanding of the dynamic interaction of slow compaction and fluid flow relevant to subsurface applications such as geologic CO₂ storage and enhanced oil recovery.

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.