3D geometry and topology of pore pathways in Opalinus clay: Implications for mass transport

Keller, Lukas M.; Holzer, Lorenz; Wepf, Roger; Gasser, Philippe

doi:10.1016/j.clay.2011.02.003

Cited by 190 publications

(153 citation statements)

References 24 publications

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“…SRXTM methods may be complemented with nanoscale approaches such as focused-ion-beam scanning electron microscopy (Keller et al, 2011;Bera et al, 2011), transmission electron microscopy (Kanitpanyacharoen et al, 2011) and X-ray nanotomography (Nelson et al, 2011;Grew et al, 2010). Overall, this round-robin experiment of SRXTM documented that all three beamlines produce similar results with microstructural resolution of approximately 2 mm.…”

Section: Discussionmentioning

confidence: 76%

A comparative study of X-ray tomographic microscopy on shales at different synchrotron facilities: ALS, APS and SLS

Kanitpanyacharoen

Parkinson

Carlo

et al. 2012

J Synchrotron Radiat

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Synchrotron radiation X-ray tomographic microscopy (SRXTM) was used to characterize the three-dimensional microstructure, geometry and distribution of different phases in two shale samples obtained from the North Sea (sample N1) and the Upper Barnett Formation in Texas (sample B1). Shale is a challenging material because of its multiphase composition, small grain size, low but significant amount of porosity, as well as strong shape-and lattice-preferred orientation. The goals of this round-robin project were to (i) characterize microstructures and porosity on the micrometer scale, (ii) compare results measured at three synchrotron facilities, and (iii) identify optimal experimental conditions of high-resolution SRXTM for fine-grained materials. SRXTM data of these shales were acquired under similar conditions at the Advanced Light Source (ALS) of Lawrence Berkeley National Laboratory, USA, the Advanced Photon Source (APS) of Argonne National Laboratory, USA, and the Swiss Light Source (SLS) of the Paul Scherrer Institut, Switzerland. The data reconstruction of all datasets was handled under the same procedures in order to compare the data quality and determine phase proportions and microstructures. With a 10Â objective lens the spatial resolution is approximately 2 mm. The sharpness of phase boundaries in the reconstructed data collected from the APS and SLS was comparable and slightly more refined than in the data obtained from the ALS. Important internal features, such as pyrite (high-absorbing), and low-density features, including pores, fractures and organic matter or kerogen (low-absorbing), were adequately segmented on the same basis. The average volume fractions of low-density features for sample N1 and B1 were estimated at 6.3 (6)% and 4.5 (4)%, while those of pyrite were calculated to be 5.6 (6)% and 2.0 (3)%, respectively. The discrepancy of data quality and volume fractions were mainly due to different types of optical instruments and varying technical set-ups at the ALS, APS and SLS.

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Section: Discussionmentioning

confidence: 76%

A comparative study of X-ray tomographic microscopy on shales at different synchrotron facilities: ALS, APS and SLS

Kanitpanyacharoen

Parkinson

Carlo

et al. 2012

J Synchrotron Radiat

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“…The geometric tortuosity is defined by the ratio of the two measured lengths. More details about the geometric tortuosity measurements are given in Keller et al [19,41]. The MIP-and c-PSD analyses are performed according to the methodology presented in Münch and Holzer [20], to measure r min , r max and b.…”

Section: Microstructure Analysis Based On X-ray Absorption Tomographymentioning

confidence: 99%

“…Nevertheless, considerable progress in the field of 3D image analysis was achieved in recent years. For example, skeletonization techniques and graph theory are now widely used to measure the geometric tortuosity (s geo ) directly from tomographic 3D-reconstructions of the complex microstructures [18,19]. Of particular importance for this study is the concept of a so-called continuous-pore size distribution (c-PSD, introduced by Münch and Holzer [20]) and computational tools which allow the simulation of mercury intrusion porosimetry (MIP).…”

Section: Introductionmentioning

confidence: 99%

“…2 and then resolving for s. We call this indirectly measured parameter the experimental tortuosity (s exp ), which must be strictly distinguished from the geometrical tortuosity (s geo ). New image analysis techniques nowadays enable the measurement of s geo directly from tomographs [18,19]. Significant differences are usually then perceived between s geo and s exp , which indicates conceptual differences between the two types of tortuosity.…”

Section: Introductionmentioning

confidence: 99%

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The influence of constrictivity on the effective transport properties of porous layers in electrolysis and fuel cells

et al. 2012

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The aim of the present investigation is to define microstructure parameters, which control the effective transport properties in porous materials for energy technology. Recent improvements in 3D-imaging (FIB-nanotomography, synchrotron X-ray tomography) and image analysis (skeletonization and graph analysis, transport simulations) open new possibilities for the study of microstructure effects. In this study, we describe novel procedures for a quantitative analysis of constrictivity, which characterizes the so-called bottleneck effect. In a first experimental part, methodological tests are performed using a porous (La,Sr)CoO 3 material (SOFC cathode). The tests indicate that the proposed procedure for quantitative analysis of constrictivity gives reproducible results even for samples with inhomogeneous microstructures (cracks, gradient of porosity). In the second part, 3D analyses are combined with measurements of ionic conductivity by impedance spectroscopy. The investigations are preformed on membranes of electrolysis cells with porosities between 0.27 and 0.8. Surprisingly, the tortuosities remain nearly constant (1.6) for the entire range of porosity. In contrast, the constrictivities vary strongly and correlate well with the measured transport resistances. Hence, constrictivity represents the dominant microstructure parameter, which controls the effective transport properties in the analysed membrane materials. An empirical relationship is then derived for the calculation of effective transport properties based on phase volume fraction, tortuosity, and constrictivity.

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“…Using Otsu threshold banalization processing method [17], SEM image of coal samples under different magnification is processed (Figure 1) and pore structure parameters, such as pore diameter, number, location, spacing, and statistical properties, are extracted. A large number of CT and SEM experiments show that the number of pores satisfies an approximate uniform distribution along the circumference, and the pore space and pore size are in normal distribution and exponential distribution [18][19][20]. According to the SEM data of coal samples, the pore statistical model with different porosity is established.…”

Section: Pore Structure Parameter Testmentioning

confidence: 99%

Reconstruction of 3D Micro Pore Structure of Coal and Simulation of Its Mechanical Properties

Guang-zhe

Zheng

2017

Advances in Materials Science and Engineering

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This article takes the low permeability coal seam in the coalfield of South Judger Basin in Xinjiang, as a research object. The pore structure characteristics of coal rock mass in low permeability coal seam were analyzed quantitatively using scanning electron microscopy (SEM) through the methods of statistics and digital image analysis. Based on the pore structure parameters and the distribution function of the coal rock mass, a three-dimensional porous cylinder model with different porosity was reconstructed by FLAC3D. The numerical simulation study of reconstructed pore model shows that (1) the porosity and the compressive strength have obvious nonlinear relation and satisfy the negative exponential relation; (2) the porosity significantly affects the stress distribution; with the increase of micro porosity, the stress distribution becomes nonuniform; (3) the compressive failures of different models are mainly shear failures, and the shape of fracture section is related to porosity; (4) the variation of seepage coefficient of the pore reconstruction model is consistent with the development of micro cracks. The micro mechanism of the deformation and failure of coal and the interaction of multiphase flow with porosity are revealed, which provides a theoretical reference for the clean development of the low permeability coal seam.

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3D geometry and topology of pore pathways in Opalinus clay: Implications for mass transport

Cited by 190 publications

References 24 publications

A comparative study of X-ray tomographic microscopy on shales at different synchrotron facilities: ALS, APS and SLS

A comparative study of X-ray tomographic microscopy on shales at different synchrotron facilities: ALS, APS and SLS

The influence of constrictivity on the effective transport properties of porous layers in electrolysis and fuel cells

Reconstruction of 3D Micro Pore Structure of Coal and Simulation of Its Mechanical Properties

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