Use of computed X-ray tomographic data for analyzing the thermodynamics of a dissociating porous sand/hydrate mixture
X-ray computed tomography (CT) is a method that has been used extensively in laboratory experiments for measuring rock properties and fluid transport behavior. More recently, CT scanning has been applied successfully to detect the presence and study the behavior of naturally occurring hydrates. In t...
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2002
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ftunivnotexas:info:ark/67531/metadc734360 2023-05-15T17:12:08+02:00 Use of computed X-ray tomographic data for analyzing the thermodynamics of a dissociating porous sand/hydrate mixture Freifeld, Barry M. Kneafsey, Timothy J. Tomutsa, Liviu Stern, Laura A. Kirby, Stephen H. United States. Office of Natural Gas and Petroleum Technology. 2002-02 6 pages Text http://digital.library.unt.edu/ark:/67531/metadc734360/ English eng Lawrence Berkeley National Laboratory rep-no: LBNL--49859 grantno: AC03-76SF00098 osti: 793798 http://digital.library.unt.edu/ark:/67531/metadc734360/ ark: ark:/67531/metadc734360 4th International Conference on Gas Hydrates, Yokahama (JP), 05/19/2002--05/23/2002 Thermodynamics Thermal Conductivity Dissociation Heat Separation Processes Mathematical Models Cat Scanning Thermal Conduction Sand Gas Hydrates Mixtures 03 Natural Gas Article 2002 ftunivnotexas 2016-04-09T22:11:49Z X-ray computed tomography (CT) is a method that has been used extensively in laboratory experiments for measuring rock properties and fluid transport behavior. More recently, CT scanning has been applied successfully to detect the presence and study the behavior of naturally occurring hydrates. In this study, we used a modified medical CT scanner to image and analyze the progression of a dissociation front in a synthetic methane hydrate/sand mixture. The sample was initially scanned under conditions at which the hydrate is stable (atmospheric pressure and liquid nitrogen temperature, 77 K). The end of the sample holder was then exposed to the ambient air, and the core was continuously scanned as dissociation occurred in response to the rising temperature. CT imaging captured the advancing dissociation front clearly and accurately. The evolved gas volume was monitored as a function of time. Measured by CT, the advancing hydrate dissociation front was modeled as a thermal conduction problem explicitly incorporating the enthalpy of dissociation, using the Stefan moving-boundary-value approach. The assumptions needed to perform the analysis consisted of temperatures at the model boundaries. The estimated value for thermal conductivity of 2.6 W/m K for the remaining water ice/sand mixture is higher than expected based on conduction alone; this high value may represent a lumped parameter that incorporates the processes of heat conduction, methane gas convection, and any kinetic effects that occur during dissociation. The technique presented here has broad implications for future laboratory and field testing that incorporates geophysical techniques to monitor gas hydrate dissociation. Article in Journal/Newspaper Methane hydrate University of North Texas: UNT Digital Library |
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Open Polar |
collection |
University of North Texas: UNT Digital Library |
op_collection_id |
ftunivnotexas |
language |
English |
topic |
Thermodynamics Thermal Conductivity Dissociation Heat Separation Processes Mathematical Models Cat Scanning Thermal Conduction Sand Gas Hydrates Mixtures 03 Natural Gas |
spellingShingle |
Thermodynamics Thermal Conductivity Dissociation Heat Separation Processes Mathematical Models Cat Scanning Thermal Conduction Sand Gas Hydrates Mixtures 03 Natural Gas Freifeld, Barry M. Kneafsey, Timothy J. Tomutsa, Liviu Stern, Laura A. Kirby, Stephen H. Use of computed X-ray tomographic data for analyzing the thermodynamics of a dissociating porous sand/hydrate mixture |
topic_facet |
Thermodynamics Thermal Conductivity Dissociation Heat Separation Processes Mathematical Models Cat Scanning Thermal Conduction Sand Gas Hydrates Mixtures 03 Natural Gas |
description |
X-ray computed tomography (CT) is a method that has been used extensively in laboratory experiments for measuring rock properties and fluid transport behavior. More recently, CT scanning has been applied successfully to detect the presence and study the behavior of naturally occurring hydrates. In this study, we used a modified medical CT scanner to image and analyze the progression of a dissociation front in a synthetic methane hydrate/sand mixture. The sample was initially scanned under conditions at which the hydrate is stable (atmospheric pressure and liquid nitrogen temperature, 77 K). The end of the sample holder was then exposed to the ambient air, and the core was continuously scanned as dissociation occurred in response to the rising temperature. CT imaging captured the advancing dissociation front clearly and accurately. The evolved gas volume was monitored as a function of time. Measured by CT, the advancing hydrate dissociation front was modeled as a thermal conduction problem explicitly incorporating the enthalpy of dissociation, using the Stefan moving-boundary-value approach. The assumptions needed to perform the analysis consisted of temperatures at the model boundaries. The estimated value for thermal conductivity of 2.6 W/m K for the remaining water ice/sand mixture is higher than expected based on conduction alone; this high value may represent a lumped parameter that incorporates the processes of heat conduction, methane gas convection, and any kinetic effects that occur during dissociation. The technique presented here has broad implications for future laboratory and field testing that incorporates geophysical techniques to monitor gas hydrate dissociation. |
author2 |
United States. Office of Natural Gas and Petroleum Technology. |
format |
Article in Journal/Newspaper |
author |
Freifeld, Barry M. Kneafsey, Timothy J. Tomutsa, Liviu Stern, Laura A. Kirby, Stephen H. |
author_facet |
Freifeld, Barry M. Kneafsey, Timothy J. Tomutsa, Liviu Stern, Laura A. Kirby, Stephen H. |
author_sort |
Freifeld, Barry M. |
title |
Use of computed X-ray tomographic data for analyzing the thermodynamics of a dissociating porous sand/hydrate mixture |
title_short |
Use of computed X-ray tomographic data for analyzing the thermodynamics of a dissociating porous sand/hydrate mixture |
title_full |
Use of computed X-ray tomographic data for analyzing the thermodynamics of a dissociating porous sand/hydrate mixture |
title_fullStr |
Use of computed X-ray tomographic data for analyzing the thermodynamics of a dissociating porous sand/hydrate mixture |
title_full_unstemmed |
Use of computed X-ray tomographic data for analyzing the thermodynamics of a dissociating porous sand/hydrate mixture |
title_sort |
use of computed x-ray tomographic data for analyzing the thermodynamics of a dissociating porous sand/hydrate mixture |
publisher |
Lawrence Berkeley National Laboratory |
publishDate |
2002 |
url |
http://digital.library.unt.edu/ark:/67531/metadc734360/ |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_source |
4th International Conference on Gas Hydrates, Yokahama (JP), 05/19/2002--05/23/2002 |
op_relation |
rep-no: LBNL--49859 grantno: AC03-76SF00098 osti: 793798 http://digital.library.unt.edu/ark:/67531/metadc734360/ ark: ark:/67531/metadc734360 |
_version_ |
1766068916809891840 |