Application of X-ray computed tomography for analyzing cleat spacing and cleat aperture in coal samples

Mazumder, Saikat; Wolf, Karl‐Heinz; Elewaut, K.; Ephraim, R

doi:10.1016/j.coal.2006.02.005

Cited by 155 publications

(82 citation statements)

References 6 publications

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“…Other studies of cleat distribution, aperture, orientation, and spacing in coals have been described using CT scans (Mazumder et al, 2006). This technique also allows correlation with other image analysis data, such as that obtained from reflected-light microscope and back scattered electron microscope observations, to obtain better visualization of distribution of coal components in three dimensions.…”

Section: Introductionmentioning

confidence: 99%

3-D Imaging of Cleat and Micro-cleat Characteristics, South Walker Creek Coals, Bowen Basin, Australia: Microfocus X-ray Computed Tomography Analysis

PermanA¹

2012

Indonesian J. Geosci.

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The Permian coals of the South Walker Creek area have a moderately to highly developed cleat system. The cleat fractures are well developed in both bright and dull bands, and generally parallel, inclined or perpendicular to the bedding planes of the seam, with the spaces open or filled by mineral matter, such as clay and carbonate minerals. Microfocus X-ray computed tomography (CT) technique was performed to identify cleat characteristics in the coal seams. This technique allows visualizing of microcleat distribution and mineralization in three dimensional images. Cleat mineralization in the coal seam occurs either as single mineral (monomineralic) or intermixed mineral (polymineralic) masses. The cross cutting relationship was shown by X-ray CT scan analysis. The timing of microcleat formation in the coal seam from early to late is carbonate minerals, clay minerals (kaolinite) plus minor high density (rutile or anatase) phases. Thus, a high resolution of microfocus X-ray CT does not only provides a better visualization, but also could identify microcleat orientation, cleat mineralization, and generation of microcleat. Keywords

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Section: Introductionmentioning

confidence: 99%

3-D Imaging of Cleat and Micro-cleat Characteristics, South Walker Creek Coals, Bowen Basin, Australia: Microfocus X-ray Computed Tomography Analysis

PermanA¹

2012

Indonesian J. Geosci.

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“…Fractures and/or cleats and their variation of occurrence through the length of a cored coal sample can be detected and parameters like size, aperture and cleat connectivity can be quantified. Mazumder et al (2006) used CT-scans to describe fracture orientations and cleat aperture and spacing in coal samples. The approach has been extended to deduce coal density and the distribution of inorganic material (Klawitter et al 2013).…”

Section: Cleat Structure Investigation By Ct Imagingmentioning

confidence: 99%

Image processing based characterisation of coal cleat networks

Busse

Dreuzy

Galindo‐Torres

et al. 2017

International Journal of Coal Geology

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Characterisation of the cleat network serves as the basis for estimating the hydraulic and mechanical seam properties which in turn are fundamental for flow and geomechanical modelling in the context of underground coal mining. Cleat and cleat network geometry can be described as a function of frequency, aperture, size, orientation relative to in situ stresses, connectivity and porosity, with mineralised and un-mineralised cleats occurring. To describe these properties, CTscans of core samples of a Bowen Basin coal in central Queensland, Australia, are analysed.A unique image processing workflow method is introduced to extract the key statistical parameters of perpendicular butt and face cleats present in a two-dimensional image. As face and butt cleats have different characteristics, the presented method distinguishes face cleats and butt cleats by direction and present detailed data for both cleat types. The results comprise cleat length, apertures, sizes, intensities, densities, shape parameter, spacing, orientation and connectivity and are therefore more comprehensive than previous cleat descriptions. Three generally different cleat geometries are considered within this study, one sample shows perpendicular face and butt cleats, the second two sets of face cleats intersected by butt cleats and the third parallel face cleats only.

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“…Because the different components of the rock have different densities, which result in different X-ray absorption coefficients, the skeleton and pore space of rocks can be distinguished. CT scanning was applied widely on the characterization of fractures [26][27][28][29][30]. OP Wennberg et al scanned the core samples to investigate the effect of natural open fractures on reservoir flow [31]; precise 3D numerical modeling was coupled with X-ray CT to analyze the heterogeneous fracture flow as well as measure porosity and permeability [32].…”

Section: Introductionmentioning

confidence: 99%

Flow Simulation of Artificially Induced Microfractures Using Digital Rock and Lattice Boltzmann Methods

Yang

Liu

et al. 2018

Energies

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Abstract:Microfractures have great significance in the study of reservoir development because they are an effective reserving space and main contributor to permeability in a large amount of reservoirs. Usually, microfractures are divided into natural microfractures and induced microfractures. Artificially induced rough microfractures are our research objects, the existence of which will affect the fluid-flow system (expand the production radius of production wells), and act as a flow path for the leakage of fluids injected to the wells, and even facilitate depletion in tight reservoirs. Therefore, the characteristic of the flow in artificially induced fractures is of great significance. The Lattice Boltzmann Method (LBM) was used to calculate the equivalent permeability of artificially induced three-dimensional (3D) fractures. The 3D box fractal dimensions and porosity of artificially induced fractures in Berea sandstone were calculated based on the fractal theory and image-segmentation method, respectively. The geometrical parameters (surface roughness, minimum fracture aperture, and mean fracture aperture), were also calculated on the base of digital cores of fractures. According to the results, the permeability lies between 0.071-3.759 (dimensionless LB units) in artificially induced fractures. The wide range of permeability indicates that artificially induced fractures have complex structures and connectivity. It was also found that 3D fractal dimensions of artificially induced fractures in Berea sandstone are between 2.247 and 2.367, which shows that the artificially induced fractures have the characteristics of self-similarity. Finally, the following relations were studied: (a) exponentially increasing permeability with increasing 3D box fractal dimension, (b) linearly increasing permeability with increasing square of mean fracture aperture, (c) indistinct relationship between permeability and surface roughness, and (d) linearly increasing 3D box fractal dimension with increasing porosity.

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Application of X-ray computed tomography for analyzing cleat spacing and cleat aperture in coal samples

Cited by 155 publications

References 6 publications

3-D Imaging of Cleat and Micro-cleat Characteristics, South Walker Creek Coals, Bowen Basin, Australia: Microfocus X-ray Computed Tomography Analysis

3-D Imaging of Cleat and Micro-cleat Characteristics, South Walker Creek Coals, Bowen Basin, Australia: Microfocus X-ray Computed Tomography Analysis

Image processing based characterisation of coal cleat networks

Flow Simulation of Artificially Induced Microfractures Using Digital Rock and Lattice Boltzmann Methods

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