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Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 459305 bytes)
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,
VOL. 8,
Q06003,
doi:10.1029/2006GC001531,
2007
Observations related to tetrahydrofuran and methane hydrates for laboratory studies of hydrate-bearing sediments
J. Y. Lee
School of Civil and Environmental Engineering, Georgia Institute of Technology, 790 Atlantic Drive NW, Atlanta, Georgia 30332-0355,
USA
T. S. Yun
School of Civil and Environmental Engineering, Georgia Institute of Technology, 790 Atlantic Drive NW, Atlanta, Georgia 30332-0355,
USA
J. C. Santamarina
School of Civil and Environmental Engineering, Georgia Institute of Technology, 790 Atlantic Drive NW, Atlanta, Georgia 30332-0355,
USA
C. Ruppel
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
Abstract
The interaction among water molecules, guest gas molecules, salts, and mineral particles determines the nucleation and growth
behavior of gas hydrates in natural sediments. Hydrate of tetrahydrofuran (THF) has long been used for laboratory studies
of gas hydrate-bearing sediments to provide close control on hydrate concentrations and to overcome the long formation history
of methane hydrate from aqueous phase methane in sediments. Yet differences in the polarizability of THF (polar molecule)
compared to methane (nonpolar molecule) raise questions about the suitability of THF as a proxy for methane in the study of
hydrate-bearing sediments. From existing data and simple macroscale experiments, we show that despite its polar nature, THF's
large molecular size results in low permittivity, prevents it from dissolving precipitated salts, and hinders the solvation
of ions on dry mineral surfaces. In addition, the interfacial tension between water and THF hydrate is similar to that between
water and methane hydrate. The processes that researchers choose for forming hydrate in sediments in laboratory settings (e.g.,
from gas, liquid, or ice) and the pore-scale distribution of the hydrate that is produced by each of these processes likely
have a more pronounced effect on the measured macroscale properties of hydrate-bearing sediments than do differences between
THF and methane hydrates themselves.
Received 16
November
2006;
accepted 27
February
2007;
published 6
June
2007.
Keywords: clathrate;
methane;
tetrahydrofuran;
sediment;
clay;
salt.
Index Terms: 3004 Marine Geology and Geophysics: Gas and hydrate systems; 5460 Planetary Sciences: Solid Surface Planets: Physical properties of materials; 1012 Geochemistry: Reactions and phase equilibria (3612, 8412).
Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 459305 bytes)
Citation: Lee, J. Y., T. S. Yun, J. C. Santamarina, and C. Ruppel
(2007),
Observations related to tetrahydrofuran and methane hydrates for laboratory studies of hydrate-bearing sediments,
Geochem. Geophys. Geosyst.,
8,
Q06003,
doi:10.1029/2006GC001531.
Copyright 2007 by the American Geophysical Union.
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