Proc. IODP, 311, Data report: gas hydrate structural and compositional characterization by spectroscopic analysis, IODP Expedition 311


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Chapter contents Abstract Introduction Methods Raman spectroscopy NMR spectroscopy Cage occupancy ratio calculation Results and discussion Site U1328: Sample 311-U1328B-2H-HydCC (Hester, 2007) Site U1328: Sample 311-U1328E-2X-Hyd17 Cage occupancy and hydration number Presence of H₂S Estimates of sample degradation due to recovery Conclusions Acknowledgments References Figures F1. Raman spectrum of hydrate, Sample H1. F2. NMR spectrum of hydrate, Sample H1. F3. Raman spectrum of hydrate, Sample H2. F4. Raman spectra of synthetic sI methane hydrate and water ice. F5. Comparison of Raman spectra from Sample H1. F6. Molar percentage sI methane hydrate. Table T1. Absolute occupancies and hydration numbers, Sample H2. PDF file		Previous \| Next doi:10.2204/iodp.proc.311.202.2008 Conclusions Gas hydrates from two cores at Expedition 311 Site U1328 were measured with Raman and NMR spectroscopy. Both samples were sI methane gas hydrate with one containing small amounts of H₂S. Interestingly, in both cases, H₂S was detected in the void gas headspace of the recovered core. It is not clear why H₂S was present in only one of the samples. Cage occupancies and hydration numbers compared well with predictions from a statistical thermodynamic gas hydrate program and other measurements on natural methane gas hydrates. Raman spectroscopy has been shown to give quantitative methane cage occupancies even when a small amount of a second component is present in the gas hydrate. In addition, water Raman peaks were used to provide a possible estimate to the degree of sample degradation resulting from unstable conditions during recovery. Top of page \| Previous \| Next

Conclusions