CAN HYDRATE DISSOLUTION EXPERIMENTS PREDICT THE FATE OF A NATURAL HYDRATE SYSTEM?
Here, we present a dissolution study of exposed hydrate from outcrops at Barkley Canyon. Previously, a field experiment on synthetic methane hydrate samples showed that mass transfer controlled dissolution in under-saturated seawater. However, seafloor hydrate outcrops have been shown to have signif...
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ftunivbritcolcir:oai:circle.library.ubc.ca:2429/1137 2023-05-15T17:12:12+02:00 CAN HYDRATE DISSOLUTION EXPERIMENTS PREDICT THE FATE OF A NATURAL HYDRATE SYSTEM? Hester, Keith C. Peltzer, E.T. Dunk, R.M. Walz, P.M. Brewer, P.G. University of British Columbia. Department of Chemical and Biological Engineering International Conference on Gas Hydrates (6th : 2008 : Vancouver, B.C.) 2008-07 271017 bytes application/pdf http://hdl.handle.net/2429/1137 eng eng Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ Sloan, E. Dendy Koh, Carolyn A. Sum, Amadeu CC-BY-NC-ND Marine hydrate Climate Carbon cycle Text Conference Paper 2008 ftunivbritcolcir 2019-10-15T17:43:35Z Here, we present a dissolution study of exposed hydrate from outcrops at Barkley Canyon. Previously, a field experiment on synthetic methane hydrate samples showed that mass transfer controlled dissolution in under-saturated seawater. However, seafloor hydrate outcrops have been shown to have significant longevity compared to expected dissolution rates based upon convective boundary layer diffusion calculations. To help resolve this apparent disconnect between the dissolution rates of synthetic and natural hydrate, an in situ dissolution experiment was performed on two distinct natural hydrate fabrics. A hydrate mound at Barkley Canyon was observed to contain a “yellow” hydrate fabric overlying a “white” hydrate fabric. The yellow hydrate fabric was associated with a light condensate phase and was hard to core. The white hydrate fabric was more porous and relatively easier to core. Cores from both fabrics were inserted to a mesh chamber within a few meters of the hydrate mound. Time-lapse photography monitored the dissolution of the hydrate cores over a two day period. The diameter shrinkage rate for the yellow hydrate was 45.5 nm/s corresponding to a retreat rate of 0.7 m/yr for an exposed surface. The white hydrate dissolved faster at 67.7 nm/s yielding a retreat rate of 1.1 m/yr. It is possible these hydrate mounds were exposed due to the fishing trawler incident in 2001. If these dissolution experiments give a correct simulation, then the exposed faces should have retreated ~ 3.5 m and 5.5 m, respectively, from 2001 to this expedition in August 2006. While the appearance of the hydrate mounds appeared quite similar to photographs taken in 2002, these dissolution experiments show natural hydrate dissolves rapidly in ambient seawater. The natural hydrate dissolution rate is on the same order as the synthetic dissolution experiment strongly implying another control for the dissolution rates of natural hydrate outcrops. Several factors could contribute to the apparent longevity of these exposed mounds from upward flux of methane-rich fluid to protective bacterial coatings. Non UBC Unreviewed Conference Object Methane hydrate University of British Columbia: cIRcle - UBC's Information Repository |
institution |
Open Polar |
collection |
University of British Columbia: cIRcle - UBC's Information Repository |
op_collection_id |
ftunivbritcolcir |
language |
English |
topic |
Marine hydrate Climate Carbon cycle |
spellingShingle |
Marine hydrate Climate Carbon cycle Hester, Keith C. Peltzer, E.T. Dunk, R.M. Walz, P.M. Brewer, P.G. CAN HYDRATE DISSOLUTION EXPERIMENTS PREDICT THE FATE OF A NATURAL HYDRATE SYSTEM? |
topic_facet |
Marine hydrate Climate Carbon cycle |
description |
Here, we present a dissolution study of exposed hydrate from outcrops at Barkley Canyon. Previously, a field experiment on synthetic methane hydrate samples showed that mass transfer controlled dissolution in under-saturated seawater. However, seafloor hydrate outcrops have been shown to have significant longevity compared to expected dissolution rates based upon convective boundary layer diffusion calculations. To help resolve this apparent disconnect between the dissolution rates of synthetic and natural hydrate, an in situ dissolution experiment was performed on two distinct natural hydrate fabrics. A hydrate mound at Barkley Canyon was observed to contain a “yellow” hydrate fabric overlying a “white” hydrate fabric. The yellow hydrate fabric was associated with a light condensate phase and was hard to core. The white hydrate fabric was more porous and relatively easier to core. Cores from both fabrics were inserted to a mesh chamber within a few meters of the hydrate mound. Time-lapse photography monitored the dissolution of the hydrate cores over a two day period. The diameter shrinkage rate for the yellow hydrate was 45.5 nm/s corresponding to a retreat rate of 0.7 m/yr for an exposed surface. The white hydrate dissolved faster at 67.7 nm/s yielding a retreat rate of 1.1 m/yr. It is possible these hydrate mounds were exposed due to the fishing trawler incident in 2001. If these dissolution experiments give a correct simulation, then the exposed faces should have retreated ~ 3.5 m and 5.5 m, respectively, from 2001 to this expedition in August 2006. While the appearance of the hydrate mounds appeared quite similar to photographs taken in 2002, these dissolution experiments show natural hydrate dissolves rapidly in ambient seawater. The natural hydrate dissolution rate is on the same order as the synthetic dissolution experiment strongly implying another control for the dissolution rates of natural hydrate outcrops. Several factors could contribute to the apparent longevity of these exposed mounds from upward flux of methane-rich fluid to protective bacterial coatings. Non UBC Unreviewed |
author2 |
University of British Columbia. Department of Chemical and Biological Engineering International Conference on Gas Hydrates (6th : 2008 : Vancouver, B.C.) |
format |
Conference Object |
author |
Hester, Keith C. Peltzer, E.T. Dunk, R.M. Walz, P.M. Brewer, P.G. |
author_facet |
Hester, Keith C. Peltzer, E.T. Dunk, R.M. Walz, P.M. Brewer, P.G. |
author_sort |
Hester, Keith C. |
title |
CAN HYDRATE DISSOLUTION EXPERIMENTS PREDICT THE FATE OF A NATURAL HYDRATE SYSTEM? |
title_short |
CAN HYDRATE DISSOLUTION EXPERIMENTS PREDICT THE FATE OF A NATURAL HYDRATE SYSTEM? |
title_full |
CAN HYDRATE DISSOLUTION EXPERIMENTS PREDICT THE FATE OF A NATURAL HYDRATE SYSTEM? |
title_fullStr |
CAN HYDRATE DISSOLUTION EXPERIMENTS PREDICT THE FATE OF A NATURAL HYDRATE SYSTEM? |
title_full_unstemmed |
CAN HYDRATE DISSOLUTION EXPERIMENTS PREDICT THE FATE OF A NATURAL HYDRATE SYSTEM? |
title_sort |
can hydrate dissolution experiments predict the fate of a natural hydrate system? |
publishDate |
2008 |
url |
http://hdl.handle.net/2429/1137 |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_rights |
Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ Sloan, E. Dendy Koh, Carolyn A. Sum, Amadeu |
op_rightsnorm |
CC-BY-NC-ND |
_version_ |
1766069000573288448 |