Understanding heterogeneous and anisotropic porous media based on
geometric properties derived from three-dimensional images
Abstract
Natural porous media is generally heterogeneous and anisotropic. The
structure of porous media plays a vital role and is often the source of
the heterogeneity and anisotropy. In physical processes such as fluid
flow in porous media, a small number of major features, here referred to
as wide channels, are responsible for the majority of the flow. The
thickness and orientation of these channels often determine the
permeability characteristics. Typically, the identification of such
major features is conducted through time-consuming and expensive
simulations. Here we propose a prompt approach based on geometric
properties derived from three-dimensional (3D) images. The size or
radius of the major features is obtained via distance maps, and their
orientations are determined by Principal Component Analysis.
Subsequently, we visualize these features with color and color
brightness according to their orientation and size, together with their
location and distribution in 3D space. The simultaneous visualization of
anisotropy (orientation) and heterogeneity (size) in one plot provides a
straightforward way to enhance our understanding of pore structure
characteristics. Besides, we propose a refined stereographic projection
method to statistically illustrate both heterogeneity and anisotropy.
Based on these insights, we further present a new way to compress the
model size in numerical simulation, therefore significantly reducing the
computational cost, while retaining its essential characteristics.