Controls on coal cleat spacing

Dawson, G. K. W.; Esterle, Joan

doi:10.1016/j.coal.2009.10.004

Cited by 123 publications

(82 citation statements)

References 11 publications

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“…In contrast, the latter type represents cleats resulting from external forces such as tectonics. Regardless of the suggested 'endogenic' processes, at least the cleat orientation seems to be controlled by the tectonic stress field (Laubach et al, 1998;Su et al, 2001;Solano-Acosta et al, 2007;Dawson & Esterle, 2010;Paul & Chatterjee, 2011; and references therein).…”

Section: Genetic Cleat Classificationmentioning

confidence: 99%

“…This is in contrast to hard coal, which are intensively examined, among other reasons because they contain coalbed methane -CBM (e.g. McCulloch et al, 1974McCulloch et al, , 1976Close & Mavor, 1991;Close, 1993;Law, 1993;Karacan & Okandan, 2000;Su et al, 2001;Solano-Acosta et al, 2007;Dawson & Esterle, 2010;Paul & Chatterjee, 2011). The present contribution is the first to focus purely on discontinuities within the Miocene MPLS-1 of central Poland.…”

Section: Introductionmentioning

confidence: 99%

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What are cleats? Preliminary studies from the Konin lignite mine, Miocene of central Poland

Widera

2014

Geologos

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Cleats (fractures, joints) are discontinuities in coals, including lignites. They are important in mining activity because of their gas and water permeability in hard coal, and mainly because of their water permeability in lignites. As opposed to hard-coal cleats, lignite cleats have not been studied in detail before. The present contribution does so, using as an example the 1st Middle-Polish Lignite Seam (MPLS-1) in the Jóźwin IIB opencast mine in central Poland. It should be mentioned here that any remarks in the present contribution concerning MPLS-1 refer exclusively to this lignite seam in the Jóźwin IIB opencast mine.The investigated discontinuities consist of two sets, i.e. the face and butt cleats, which are roughly oriented NW-SE and NE-SW, respectively. The mean spacing of the face cleats is ~12.4 cm, while the mean spacing of the butt cleats is ~12.8 cm. The maximum average aperture is ~4.9 mm for the face cleats and ~4.1 mm for the butt cleats. The cleat spacing and aperture do not depend on the lignite thickness, but the cleat spacing increases with increasing mineral-matter and xylite content, whereas the aperture increases when the contents decrease. The regional folding and local salt diapirism tentatively explain the formation of the orthogonal system of the lignite cleats, partly because of the parallelism of the face cleats and the major tectonic directions in central Poland.

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Section: Genetic Cleat Classificationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

What are cleats? Preliminary studies from the Konin lignite mine, Miocene of central Poland

Widera

2014

Geologos

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“…This might be due to the fact that the cited study (Wang et al, 2009) focused on largescale major cleats. The image processing based method captured the more common small-scale cleats with spacings of less than a millimetre, as have been described by Dawson and Esterle (2010). This result highlights the usefulness of high-resolution CT-scanning, but also the fact that spacing measurements are limited by the diameter of the core sample.…”

Section: 1mentioning

confidence: 58%

“…Characteristic sizes of cleat spacings are between 10 -25 mm (Wang et al, 2009). Dawson and Esterle (2010) found that for specific vitrain layers, the cleats could be spaced as closely as less than a millimetre apart. Further, the spacing of the cleats tended to be proportional to fracture size for given types of cleats.…”

Section: Cleat Spacingmentioning

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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“…Cleats in the high-ash Carlisle lignite (R o~0 .23%) are spaced more widely than those in the somewhat lower ash and more mature Fancy Farm lignite (R o~0 .33%, and both are more widely spaced than the low-ash portions of the Weakly lignite (R o~0 .35%). Fuller treatment of the interplay of coal type, and rank on cleating can be found in Law (1993), Laubach et al (1998), and Dawson and Esterle (2010).…”

Section: General Physical Changes To Coal With Rankmentioning

confidence: 99%