Parallel Lattice Boltzmann Computing and Applications in Core Sample Feature Evaluation

Abstract

Micro-CT scans with QEMSCAN mapping provide visualization of core samples to quantify heterogeneous physical properties important for subsurface flow including, as examples, pore size distribution and connectivity, mineral compositions, porosity and permeability, amongst many others. 3D high-resolution micro-CT scans can deliver a very high level of microstructures detail, which also implies enormous numerical data sets and associated computational processing load. It is, therefore, important to understand (1) the voxel resolution of micro-CT scans required to retain physical structure fidelity (e.g., mineral compositions, pore size and throats, and porosity and tortuosity), (2) the sensitivity of individual mineral property and voxel resolution on the directional permeability, and (3) the smallest sample size that provides reliable and representative transport calculations (e.g., directional permeability and connectivity). The lattice Boltzmann method is capable of simulating flow in both open pore spaces and porous media and is used here to allow for flow in multiple matrices (quartz aggregate and low-permeable clay matrix). As an application example, a permeability study of the Precipice Sandstone from the Chinchilla 4 well in the Surat Basin has been conducted. Regarding the Chinchilla sample, we established that (1) the composition ratio is relatively sensitive to voxel resolution: higher resolution imaging is required to retain narrow pore throats and excessively coarsened voxel resolutions result in severe loss of internal microstructures information; (2) both voxel resolutions and individual mineral properties affect flow dynamics, and the clay permeability slightly affects the whole permeability at ∼nD scale; (3) it is not feasible to define the accurate ratio of lattice nodes versus pore apertures for meeting the grid independence due to the complex sample tortuosity;

Lattice Boltzmann-Based Approaches for Pore-Scale Reactive Transport

“…LBM has been extensively applied for a variety of complex fl uid fl ow problems, including single and multi-phase fl ow and reactive transport in complex geometries obtained from micro-CT imaging (Ladd 1994;Martys and Chen 1996;Keehm 2004;Fredrich et al 2006;Boek et al 2014;Jiang and Tsuji 2014;Gao et al 2015). A major advantage of LBM is the relative ease of accounting for very complex pore-geometries from segmented image data due to its discrete dynamics (Chen and Doolen 1998).…”

“…This fi nding revealed the representative volume and length scales that are necessary to characterize geometrically complex porous media and predict fl uid transport properties at the macroscale. More recently, LB-based approaches were used to investigate the porosity dynamics due to precipitation and dissolution in 3-D pore structures from micro-CT images (Jiang and Tsuji 2014;Gao et al 2015). These recent studies using micro-CT images can be combined with other imaging techniques (e.g., backscattered electron mapping coupled with X-ray based methods) for mineralogical distribution (Peters 2009;Landrot et al 2012) to investigate coupled fl uid fl ow and geochemistry, as well as the emergence of coupled behaviors due to biogeochemical reactions.…”

Saturated water conductivity estimation based on X-ray CT images – evaluation of the impact of thresholding errors

“…There are three main approaches to pore-scale modelling, i.e. the lattice Boltzmann method (Gao et al, 2015;McClure et al, 2014), the pore network modelling (Bultreys et al, 2015;Ngom et al, 2011) and the Navier-Stokes (NS) model (Icardi et al, 2014;Muljadi et al, 2016). NS models are differential equations which can be discretised in different manners, e.g.…”

Effect of Bedding Planes on the Permeability and Diffusivity Anisotropies of Berea Sandstone

“…LBM has been employed in various fields, including earth sciences and geology, to understand transport in open pores and porous structures. For example, it was used by Auzerais et al (1996) to examine the scale dependence and influence of heterogeneities of transport properties in Fontainebleau sandstone; by Okabe and Blunt (2004) to predict the permeability of porous media based on 3-D CT images and reconstructed 2-D images; by Gao et al (2015) to study the permeability of sandstones for the voxel size dependency; and by Genty et al (2017) to study the microfracture of indurated argillite Oparinus clay and obtain the effective diffusion coefficient. Finally, the experimental and numerical results were compared to explore the relationship between the anisotropic transport parameters and bedding plane direction.…”