Factors controlling the mechanical properties degradation and permeability of coal subjected to liquid nitrogen freeze-thaw

Abstract Freeze-thaw induced fracturing coal by liquid nitrogen (LN2) injection exerts a significant positive effect on the fracture permeability enhancement of the coal reservoir. To evaluate the different freeze-thaw variables which modify the mechanical properties of treated coals, the effects of...

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Autores principales:	Lei Qin, Cheng Zhai, Shimin Liu, Jizhao Xu
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/603e0168736341c89936a4393bee0234
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spelling	oai:doaj.org-article:603e0168736341c89936a4393bee02342021-12-02T12:30:12ZFactors controlling the mechanical properties degradation and permeability of coal subjected to liquid nitrogen freeze-thaw10.1038/s41598-017-04019-72045-2322https://doaj.org/article/603e0168736341c89936a4393bee02342017-06-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-04019-7https://doaj.org/toc/2045-2322Abstract Freeze-thaw induced fracturing coal by liquid nitrogen (LN2) injection exerts a significant positive effect on the fracture permeability enhancement of the coal reservoir. To evaluate the different freeze-thaw variables which modify the mechanical properties of treated coals, the effects of freezing time, number of freeze-thaw cycles, and the moisture content of coal were studied using combined uniaxial compression and acoustic emission testing systems. Freezing the samples with LN2 for increasing amounts of time degraded the strength of coal within a certain limit. Comparison to freezing time, freeze-thaw cycling caused much more damage to the coal strength. The third variable studied, freeze-thaw damage resulting from high moisture content, was restricted by the coal’s moisture saturation limit. Based on the experimental results, equations describing the amount of damage caused by each of the different freeze-thaw variables were empirically regressed. Additionally, by using the ultrasonic wave detection method and fractal dimension analyses, how freeze-thaw induced fractures in the coal was quantitatively analyzed. The results also showed that the velocity of ultrasonic waves had a negative correlation with coal permeability, and the freeze-thaw cycles significantly augment the permeability of frozen-thawed coal masses.Lei QinCheng ZhaiShimin LiuJizhao XuNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-11 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Lei Qin Cheng Zhai Shimin Liu Jizhao Xu Factors controlling the mechanical properties degradation and permeability of coal subjected to liquid nitrogen freeze-thaw
description	Abstract Freeze-thaw induced fracturing coal by liquid nitrogen (LN2) injection exerts a significant positive effect on the fracture permeability enhancement of the coal reservoir. To evaluate the different freeze-thaw variables which modify the mechanical properties of treated coals, the effects of freezing time, number of freeze-thaw cycles, and the moisture content of coal were studied using combined uniaxial compression and acoustic emission testing systems. Freezing the samples with LN2 for increasing amounts of time degraded the strength of coal within a certain limit. Comparison to freezing time, freeze-thaw cycling caused much more damage to the coal strength. The third variable studied, freeze-thaw damage resulting from high moisture content, was restricted by the coal’s moisture saturation limit. Based on the experimental results, equations describing the amount of damage caused by each of the different freeze-thaw variables were empirically regressed. Additionally, by using the ultrasonic wave detection method and fractal dimension analyses, how freeze-thaw induced fractures in the coal was quantitatively analyzed. The results also showed that the velocity of ultrasonic waves had a negative correlation with coal permeability, and the freeze-thaw cycles significantly augment the permeability of frozen-thawed coal masses.
format	article
author	Lei Qin Cheng Zhai Shimin Liu Jizhao Xu
author_facet	Lei Qin Cheng Zhai Shimin Liu Jizhao Xu
author_sort	Lei Qin
title	Factors controlling the mechanical properties degradation and permeability of coal subjected to liquid nitrogen freeze-thaw
title_short	Factors controlling the mechanical properties degradation and permeability of coal subjected to liquid nitrogen freeze-thaw
title_full	Factors controlling the mechanical properties degradation and permeability of coal subjected to liquid nitrogen freeze-thaw
title_fullStr	Factors controlling the mechanical properties degradation and permeability of coal subjected to liquid nitrogen freeze-thaw
title_full_unstemmed	Factors controlling the mechanical properties degradation and permeability of coal subjected to liquid nitrogen freeze-thaw
title_sort	factors controlling the mechanical properties degradation and permeability of coal subjected to liquid nitrogen freeze-thaw
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/603e0168736341c89936a4393bee0234
work_keys_str_mv	AT leiqin factorscontrollingthemechanicalpropertiesdegradationandpermeabilityofcoalsubjectedtoliquidnitrogenfreezethaw AT chengzhai factorscontrollingthemechanicalpropertiesdegradationandpermeabilityofcoalsubjectedtoliquidnitrogenfreezethaw AT shiminliu factorscontrollingthemechanicalpropertiesdegradationandpermeabilityofcoalsubjectedtoliquidnitrogenfreezethaw AT jizhaoxu factorscontrollingthemechanicalpropertiesdegradationandpermeabilityofcoalsubjectedtoliquidnitrogenfreezethaw
_version_	1718394400714784768

Factors controlling the mechanical properties degradation and permeability of coal subjected to liquid nitrogen freeze-thaw

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