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Title: Measurement and Modeling of Sorption-Induced Strain and Permeability Changes in Coal

Abstract

Strain caused by the adsorption of gases was measured in samples of subbituminous coal from the Powder River basin of Wyoming, U.S.A., and high-volatile bituminous coal from the Uinta-Piceance basin of Utah, U.S.A. using a newly developed strain measurement apparatus. The apparatus can be used to measure strain on multiple small coal samples based on the optical detection of the longitudinal strain. The swelling and shrinkage (strain) in the coal samples resulting from the adsorption of carbon dioxide, nitrogen, methane, helium, and a mixture of gases was measured. Sorption-induced strain processes were shown to be reversible and easily modeled with a Langmuir-type equation. Extended Langmuir theory was applied to satisfactorily model strain caused by the adsorption of gas mixtures using the pure gas Langmuir strain constants. The amount of time required to obtain accurate strain data was greatly reduced compared to other strain measurement methods. Sorption-induced changes in permeability were also measured as a function of pres-sure. Cleat compressibility was found to be variable, not constant. Calculated variable cleat-compressibility constants were found to correlate well with previously published data for other coals. During permeability tests, sorption-induced matrix shrinkage was clearly demonstrated by higher permeability values at lower pore pressures whilemore » holding overburden pressure constant. Measured permeability data were modeled using three dif-ferent permeability models from the open literature that take into account sorption-induced matrix strain. All three models poorly matched the measured permeability data because they overestimated the impact of measured sorption-induced strain on permeabil-ity. However, by applying an experimentally derived expression to the measured strain data that accounts for the confining overburden pressure, pore pressure, coal type, and gas type, the permeability models were significantly improved.« less

Authors:
Publication Date:
Research Org.:
Idaho National Lab. (INL), Idaho Falls, ID (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
911830
Report Number(s):
INL/EXT-06-11832
TRN: US200801%%273
DOE Contract Number:  
DE-AC07-99ID-13727
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
01 - COAL, LIGNITE, AND PEAT, 03 - NATURAL GAS; ADSORPTION; BITUMINOUS COAL; CARBON DIOXIDE; COAL; COMPRESSIBILITY; DETECTION; GASES; HELIUM; METHANE; MIXTURES; NITROGEN; OVERBURDEN; PERMEABILITY; PORE PRESSURE; POWDER RIVER BASIN; SHRINKAGE; STRAINS; SUBBITUMINOUS COAL; SWELLING; Coal, sorption, strain, permeability

Citation Formats

Robertson, Eric P. Measurement and Modeling of Sorption-Induced Strain and Permeability Changes in Coal. United States: N. p., 2005. Web. doi:10.2172/911830.
Robertson, Eric P. Measurement and Modeling of Sorption-Induced Strain and Permeability Changes in Coal. United States. https://doi.org/10.2172/911830
Robertson, Eric P. 2005. "Measurement and Modeling of Sorption-Induced Strain and Permeability Changes in Coal". United States. https://doi.org/10.2172/911830. https://www.osti.gov/servlets/purl/911830.
@article{osti_911830,
title = {Measurement and Modeling of Sorption-Induced Strain and Permeability Changes in Coal},
author = {Robertson, Eric P},
abstractNote = {Strain caused by the adsorption of gases was measured in samples of subbituminous coal from the Powder River basin of Wyoming, U.S.A., and high-volatile bituminous coal from the Uinta-Piceance basin of Utah, U.S.A. using a newly developed strain measurement apparatus. The apparatus can be used to measure strain on multiple small coal samples based on the optical detection of the longitudinal strain. The swelling and shrinkage (strain) in the coal samples resulting from the adsorption of carbon dioxide, nitrogen, methane, helium, and a mixture of gases was measured. Sorption-induced strain processes were shown to be reversible and easily modeled with a Langmuir-type equation. Extended Langmuir theory was applied to satisfactorily model strain caused by the adsorption of gas mixtures using the pure gas Langmuir strain constants. The amount of time required to obtain accurate strain data was greatly reduced compared to other strain measurement methods. Sorption-induced changes in permeability were also measured as a function of pres-sure. Cleat compressibility was found to be variable, not constant. Calculated variable cleat-compressibility constants were found to correlate well with previously published data for other coals. During permeability tests, sorption-induced matrix shrinkage was clearly demonstrated by higher permeability values at lower pore pressures while holding overburden pressure constant. Measured permeability data were modeled using three dif-ferent permeability models from the open literature that take into account sorption-induced matrix strain. All three models poorly matched the measured permeability data because they overestimated the impact of measured sorption-induced strain on permeabil-ity. However, by applying an experimentally derived expression to the measured strain data that accounts for the confining overburden pressure, pore pressure, coal type, and gas type, the permeability models were significantly improved.},
doi = {10.2172/911830},
url = {https://www.osti.gov/biblio/911830}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Oct 01 00:00:00 EDT 2005},
month = {Sat Oct 01 00:00:00 EDT 2005}
}