Evaluation of the damages of permeability and effective porosity of tectonically deformed coals

Evaluation of the damages of permeability and effective porosity of tectonically deformed coals A high rank coal was tested in terms of loading and unloading to characterize changes in the permeability and effective porosity of tectonically deformed coals. The coal sample, an anthracite, is subdivided into four types according to its structure, namely, the primary structure coal, cataclastic coal (the weakest deformation coal), granulated coal (the moderate deformation coal), and mylonitic coal (the intensest deformation coal); the latter three types are considered to be tectonic deformation coals. Permeability of tectonically deformed coals shows a negative exponential relation to stress. The intenser the structural deformation in coal is, the lower the permeability. Two evaluation parameters, namely, loss rate m (0.8318–0.9476) and damage rate n (0.447–0.6556), which are related to changes in permeability, increase with increasing structural deformation in coal. The cleat compressibility factor declines with increasing difference in effective stress and increases with increasing structural deformation in coal. This study proposes a calculation method for evaluating the porosity damage. Similar to the loss ratio and damage rate, this parameter (η) increases with increasing structural deformation in coal and reveals the relationship between the porosity damage and the structural deformation in coal. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Arabian Journal of Geosciences Springer Journals

Evaluation of the damages of permeability and effective porosity of tectonically deformed coals

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Publisher
Springer Journals
Copyright
Copyright © 2017 by Saudi Society for Geosciences
Subject
Earth Sciences; Earth Sciences, general
ISSN
1866-7511
eISSN
1866-7538
D.O.I.
10.1007/s12517-017-3140-8
Publisher site
See Article on Publisher Site

Abstract

A high rank coal was tested in terms of loading and unloading to characterize changes in the permeability and effective porosity of tectonically deformed coals. The coal sample, an anthracite, is subdivided into four types according to its structure, namely, the primary structure coal, cataclastic coal (the weakest deformation coal), granulated coal (the moderate deformation coal), and mylonitic coal (the intensest deformation coal); the latter three types are considered to be tectonic deformation coals. Permeability of tectonically deformed coals shows a negative exponential relation to stress. The intenser the structural deformation in coal is, the lower the permeability. Two evaluation parameters, namely, loss rate m (0.8318–0.9476) and damage rate n (0.447–0.6556), which are related to changes in permeability, increase with increasing structural deformation in coal. The cleat compressibility factor declines with increasing difference in effective stress and increases with increasing structural deformation in coal. This study proposes a calculation method for evaluating the porosity damage. Similar to the loss ratio and damage rate, this parameter (η) increases with increasing structural deformation in coal and reveals the relationship between the porosity damage and the structural deformation in coal.

Journal

Arabian Journal of GeosciencesSpringer Journals

Published: Aug 15, 2017

References

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