| Summary: | The dedicated gas hydrate coring/drilling program was carried out under National Gas
Hydrate Program (NGHP) in four Indian offshore areas (Kerala-Konkan, Krishna-
Godavari, Mahanadi and Andman) during 28th April to 19th August, 2006. During
NGHP Expedition 01, 2006, total of 39 holes were drilled/cored at 21 sites in these areas.
The gas hydrates have been found to be present in large quantities in Indian offshore
areas particularly in KG basin. More than 130 confirmed solid gas hydrate samples were
recovered during this hydrate coring/drilling program. The laboratory analysis was
carried out on the 34 natural gas hydrate samples recovered from offshore India. The gas
hydrate characterization was carried out using the microscopic techniques such as
Raman, 13C NMR and XRD for its structure, cavity occupancy and hydration number.
The gas hydrates occur in grayish green fine sediments, gray medium sands and white
volcanic ash as pore-filling hydrate and massive hydrates in fractured shale/clay. The
visible massive gas hydrates developed especially at Site NGHP 1-10B, 10C, 10D and
21A in K G area. The structures of the gas hydrates in the studied samples are all sI, with
methane as the dominant guest molecule. The occupancy of methane in large cage is
almost complete, while it is variable in the small cage (0.75 to 0.99). The hydration
number is 6.10 ± 0.15 for most of the hydrates in the samples studied. This paper presents
the results of the laboratory analysis on the structural characterization of natural gas
hydrates in core samples from offshore India.
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