Transport Simulations on Scanning Transmission Electron Microscope Images of Nanoporous Shale

Digital rock physics is an often-mentioned approach to better understand and model transport processes occurring in tight nanoporous media including the organic and inorganic matrix of shale. Workflows integrating nanometer-scale image data and pore-scale simulations are relatively undeveloped, howe...

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Bibliographic Details
Published in:Energies (Basel) 2020-12, Vol.13 (24), p.6665
Main Authors: Frouté, Laura, Wang, Yuhang, McKinzie, Jesse, Aryana, Saman, Kovscek, Anthony
Format: Article
Language:English
Subjects:
Computational fluid dynamics
Digital imaging
Electron microscopy
ENGINEERING
Fluid mechanics
Gas flow
Image acquisition
Image transmission
Ion beams
lattice Boltzmann method
Mathematical models
nanoporosity
Percolation
Permeability
Physics
Porosity
Scanning transmission electron microscopy
Shale
Simulation
Tomography
Transmission electron microscopy
Transport processes
Workflow
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Description
Summary:Digital rock physics is an often-mentioned approach to better understand and model transport processes occurring in tight nanoporous media including the organic and inorganic matrix of shale. Workflows integrating nanometer-scale image data and pore-scale simulations are relatively undeveloped, however. In this paper, a workflow is demonstrated progressing from sample acquisition and preparation, to image acquisition by Scanning Transmission Electron Microscopy (STEM) tomography, to volumetric reconstruction to pore-space discretization to numerical simulation of pore-scale transport. Key aspects of the workflow include (i) STEM tomography in high angle annular dark field (HAADF) mode to image three-dimensional pore networks in µm-sized samples with nanometer resolution and (ii) lattice Boltzmann method (LBM) simulations to describe gas flow in slip, transitional, and Knudsen diffusion regimes. It is shown that STEM tomography with nanoscale resolution yields excellent representation of the size and connectivity of organic nanopore networks. In turn, pore-scale simulation on such networks contributes to understanding of transport and storage properties of nanoporous shale. Interestingly, flow occurs primarily along pore networks with pore dimensions on the order of tens of nanometers. Smaller pores do not form percolating pathways in the sample volume imaged. Apparent gas permeability in the range of 10−19 to 10−16 m2 is computed.
ISSN:1996-1073
1996-1073
DOI:10.3390/en13246665