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Observations related to tetrahydrofuran and methane hydrates for laboratory studies of hydrate-bearing sediments

January 1, 2007

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.

Publication Year 2007
Title Observations related to tetrahydrofuran and methane hydrates for laboratory studies of hydrate-bearing sediments
DOI 10.1029/2006GC001531
Authors J.Y. Lee, T.S. Yun, J.C. Santamarina, C. Ruppel
Publication Type Article
Publication Subtype Journal Article
Series Title Geochemistry, Geophysics, Geosystems
Index ID 70120690
Record Source USGS Publications Warehouse
USGS Organization Coastal and Marine Geology Program