Seismic Evidence for Widespread Gas Hydrate Formation, Offshore West Africa.

Cunningham, Robert and Lindholm, Rosanne M. (2000) Seismic Evidence for Widespread Gas Hydrate Formation, Offshore West Africa. In: Petroleum systems of South Atlantic margins. , ed. by Mello, M. R. and Katz, B. J.. AAPG Memoir, 73 . AAPG, Tulsa, Okla., pp. 93-105.

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Abstract

Seismic reflection data recorded offshore west Africa reveal the presence of extensive bottom simulating
reflectors (BSRs) on the continental slope off the Niger and Congo River Deltas. Cumulative surface
areas encompassing the Nigeria and Congo BSR occurrences are approximately 11,000 km2 and 4000 km2,
respectively. West African BSRs display many of the characteristics that have commonly been ascribed to
submarine gas hydrates elsewhere in the world, including reflection polarity reversal relative to the sea
floor reflection, consistency between depth of the BSR and base of the gas hydrate stability field, geometric
relationships between BSR and bedding plane reflections, and a positive correlation between the su~water
bottom depth of the BSR and the water depth. Widespread BSRs along the Nigeria and Congo continental
slopes generally occur in areas of complex structure and where water depths are greater than 1200
m. The relationship between gas hydrate occurrence and structure exists, in part, because BSRs are more
easily recognized on seismic sections where the BSRs cut across dipping stratigraphic reflections.
However, faults and dipping stratigraphy also facilitate migration of biogenic or thermogenic gas to the
base of the gas hydrate stability zone, enabling the formation of BSRs.

Document Type: Book chapter
Keywords: Seismic reflection data, bottom simulating reflectors (BSR) continental slope, Niger, Congo River Deltas, West Africa
Publisher: AAPG
Projects: Enrichment
Date Deposited: 16 Jul 2018 06:10
Last Modified: 16 Jul 2018 06:10
URI: https://oceanrep.geomar.de/id/eprint/43655

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