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The Nature of Gas Hydrates on the Nigerian Continental Slope
Author(s) -
BROOKS JAMES M.,
BRYANT WILLIAM R.,
BERNARD BERNIE B.,
CAMERON NICK R.
Publication year - 2000
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2000.tb06761.x
Subject(s) - clathrate hydrate , methane , natural gas , hydrocarbon , butane , geology , methane gas , associated petroleum gas , submarine pipeline , mineralogy , geochemistry , hydrate , chemistry , oceanography , organic chemistry , catalysis
A bstract : Gas hydrates were collected in six‐meter piston cores during surface geochemical exploration (SGE) surveys in the deep and ultra deepwaters of Nigeria during 1991, 1996, and 1998. To date, gas hydrates have been collected in about 21 cores out of the more than 800 core collections on the Nigerian margin. This represents a 2.5% recovery ratio of gas hydrated cores on this margin at sites that are potential conduits for the upward migration of hydrocarbons (i.e., the core locations are sited based on two‐ and three‐dimensional seismic overfaults, mounds, acoustic wipe‐outs, etc.). Unlike the Northern Gulf of Mexico where the authors have retrieved a significant percentage of thermogenic hydrates in piston cores, all the gas hydrate collections offshore Nigeria to date are primarily biogenic in nature (methane more than 99% of the hydrocarbon gases; δ 13C generally light, −60 to −117%). A few of these gas hydrated sites do contain a mixed thermogenic gas component (ethane to butane gases up to a few hundred ppm of total hydrocarbon gas) but even at these sites the primary gas in the hydrates is methane.