Presence and consequences of coexisting methane gas with hydrate under two phase water-hydrate stability conditions
Presence and consequences of coexisting methane gas with hydrate under two phase water-hydrate stability conditions
Methane hydrate saturation estimates from remote geophysical data and borehole logs are needed to assess the role of hydrates in climate change, continental slope stability, and energy resource potential. Here we present laboratory hydrate formation/dissociation experiments in which we determined the methane hydrate content independently from pore pressure and temperature and from electrical resistivity. Using these laboratory experiments, we demonstrate that hydrate formation does not take up all the methane gas or water even if the system is under two phase water-hydrate stability conditions and gas is well distributed in the sample. The experiment started with methane gas and water saturations of 16.5% and 83.5%, respectively; during the experiment, hydrate saturation proceeded up to 26% along with 12% gas and 62% water remaining in the system. The coexistence of hydrate and gas is one possible explanation for discrepancies between estimates of hydrate saturation from electrical and acoustic methods. We suggest that an important mechanism for this coexistence is the formation of a hydrate film enveloping methane gas bubbles, trapping the remaining gas inside.
coexisting gas, gas hydrate, laboratory hydrate
3377-3390
Sahoo, Sourav K.
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Marín-Moreno, Héctor
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North, Laurence J.
086e30f4-b8be-429c-b6a0-5cc0c3902e53
Falcon-Suarez, Ismael
f5cdbc61-326b-424d-a90f-593a8698a4d2
Madhusudhan, Bangalore N.
e139e3d3-2992-4579-b3f0-4eec3ddae98c
Best, Angus I.
f962ede8-2ff2-42b6-baa1-88d93dfb08dd
Minshull, Tim A.
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31 May 2018
Sahoo, Sourav K.
6dab0376-36df-44c5-9f36-cb4a29d9b03b
Marín-Moreno, Héctor
e466cafd-bd5c-47a1-8522-e6938e7086a4
North, Laurence J.
086e30f4-b8be-429c-b6a0-5cc0c3902e53
Falcon-Suarez, Ismael
f5cdbc61-326b-424d-a90f-593a8698a4d2
Madhusudhan, Bangalore N.
e139e3d3-2992-4579-b3f0-4eec3ddae98c
Best, Angus I.
f962ede8-2ff2-42b6-baa1-88d93dfb08dd
Minshull, Tim A.
bf413fb5-849e-4389-acd7-0cb0d644e6b8
Sahoo, Sourav K., Marín-Moreno, Héctor, North, Laurence J., Falcon-Suarez, Ismael, Madhusudhan, Bangalore N., Best, Angus I. and Minshull, Tim A.
(2018)
Presence and consequences of coexisting methane gas with hydrate under two phase water-hydrate stability conditions.
Journal of Geophysical Research: Solid Earth, 123 (5), .
(doi:10.1029/2018JB015598).
Abstract
Methane hydrate saturation estimates from remote geophysical data and borehole logs are needed to assess the role of hydrates in climate change, continental slope stability, and energy resource potential. Here we present laboratory hydrate formation/dissociation experiments in which we determined the methane hydrate content independently from pore pressure and temperature and from electrical resistivity. Using these laboratory experiments, we demonstrate that hydrate formation does not take up all the methane gas or water even if the system is under two phase water-hydrate stability conditions and gas is well distributed in the sample. The experiment started with methane gas and water saturations of 16.5% and 83.5%, respectively; during the experiment, hydrate saturation proceeded up to 26% along with 12% gas and 62% water remaining in the system. The coexistence of hydrate and gas is one possible explanation for discrepancies between estimates of hydrate saturation from electrical and acoustic methods. We suggest that an important mechanism for this coexistence is the formation of a hydrate film enveloping methane gas bubbles, trapping the remaining gas inside.
Text
2018JB015598
- Accepted Manuscript
Text
Sahoo et al 2018 JGR
- Version of Record
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Accepted/In Press date: 4 May 2018
e-pub ahead of print date: 11 May 2018
Published date: 31 May 2018
Additional Information:
Funding Information:
We acknowledge funding from the UK Natural Environment Research Council (grant NE/J020753/1). The data are available in the supplemental informa tion and at the National Geoscience Data Centre, UK (www.bgs.ac.uk/ser vices/NGDC/home.html). Hydrate phase boundaries were calculated by the Centre for Gas Hydrate Research at Heriot-Watt University (http://www.pet. hw.ac.uk/research/hydrate), using the Heriot-Watt Hydrate and Phase Behaviour Programme (HWHYD). We thank K. Amalokwu and E. Attias for their advice on experimental trouble shooting. We thank P. J. Talling for his valuable comments on the manuscript. T. A. Minshull was supported by a Royal Society Wolfson Research Merit award. We also thank the editor Andre Revil, associate editor Ludmila Adam, reviewer Ingo Pecher, and two other anonymous reviewers for their valuable comments.
Keywords:
coexisting gas, gas hydrate, laboratory hydrate
Identifiers
Local EPrints ID: 420768
URI: http://eprints.soton.ac.uk/id/eprint/420768
ISSN: 2169-9356
PURE UUID: 2fb3dab2-84f2-4358-b572-723c48c4b459
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Date deposited: 16 May 2018 16:30
Last modified: 16 Mar 2024 06:38
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Contributors
Author:
Sourav K. Sahoo
Author:
Héctor Marín-Moreno
Author:
Laurence J. North
Author:
Ismael Falcon-Suarez
Author:
Angus I. Best
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