A novel architecture for pore network modelling with applications to permeability of porous media

Abstract

Network models of porous media are beneficial for predicting the evolution of macroscopic mass transport properties. This work proposes a novel bi-regular network model based on truncated octahedral support. With the model, pore systems with different pore coordination spectra for a given average coordination number can be constructed to match experimental data. This feature and the maximum allowed pore coordination of 14 make the proposed model more realistic and flexible than the existing models based on cubic supports. Limestone is used as a study material to illustrate the model performance. Experimental pore space data for this material obtained by X-ray tomography (CT) are used for constructing microstructure-informed model realisations. It is demonstrated that with these realisations the experimentally measured permeability of the material can be predicted. The model is further used to assess the effects of pore connectivity and porosity on the permeability. It is shown that the effect of pore connectivity is substantially stronger than the effect of porosity. A strategy for calculating the evolution of permeability with damage-related pore space changes is also described. The results reveal the effects of the mechanical properties of the medium on the permeability evolution as a function of damage evolution. Developments of this strategy are suggested for deriving mechanism-based constitutive laws for engineering applications.

A Network Model for Diffusion in Media with Partially Resolvable Pore Space Characteristics

“…One remedy is to construct a network based on a regular cellular complex which represents the spatial distribution of pores in an average sense, i.e., to perform a prior "geometric homogenisation" of the medium. In a previous work (Jivkov et al 2013) we have proposed a complex of compactly packed truncated octahedral cells, Fig. 2a, considering that a cell of this shape represents the average neighbourhood of a pore in a material.…”

“…This is a mapping, suitable for pore systems containing predominantly spherical pores with connectivity and throat size statistics obtained from experimental data (Jivkov et al 2013). It is also suitable for pore systems with only pore size distribution available from experimental techniques.…”

“…In such cases, topologically representative networks can be constructed by a selection of a regular basis of pores and throats connecting neighbouring pores, and subsequent elimination of throats to achieve the topological constraints. This has been illustrated for average coordination number in simple bases, such as cubic lattice, e.g., (Dixit et al 1998(Dixit et al , 2000Raoof and Hassanizadeh 2010), as well as for full coordination spectra in a bi-regular lattice (Jivkov et al 2013). A limitation of such constructions is that potential correlations between sizes of pores and adjacent throats are not accounted for.…”

Permeability and acoustic velocity controlling factors determined from x-ray tomography images of carbonate rocks

“…Carbonate rocks usually present a wide range of permeability for the same porosity value because of a marked variability in the connectivity of pores, both with respect to average coordination number (the number of neighboring pores) and pore-throat diameter (Lucia, 2007;Ahr, 2008;Hollis et al, 2010;Jivkov et al, 2013). Raoof and Hassanizadeh (2012) showed the importance of including the coordination number to estimate the permeability.…”

“…Raoof and Hassanizadeh (2012) showed the importance of including the coordination number to estimate the permeability. Later, Jivkov et al (2013) demonstrated that the coordination number is a more important control parameter on permeability than total porosity. However, the pore geometry, pore-throat radius, and coordination number cannot be reliably quantified using thin-section images, because three-dimensional (3-D) information cannot be assessed.…”