Seismic Evidence for Widespread Gas Hydrate Formation, Offshore West Africa
Published:January 01, 2000
Robert Cunningham, Rosanne M. Lindholm, 2000. "Seismic Evidence for Widespread Gas Hydrate Formation, Offshore West Africa", Petroleum Systems of South Atlantic Margins, Marcio Rocha Mello, Barry J. Katz
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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 sub-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.
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Petroleum Systems of South Atlantic Margins
“Giant oil and gas fields have been discovered through recent exploration in the deep and ultra-deep water regions of Angola, Brazil, and Nigeria. This volume includes 1. Descriptions of the petroleum geology of more than 12 basins along the two margins 2. Discussion of various components of the petroleum systems within these basins 3. Discussion on the use of the petroleum systems concept in the South Atlantic marginal basins to classify and characterize the diversity of the systems 4. Methodologies used in the assessment of petroleum system components 5. Overviews of the different components of the region's petroleum systems. Petroleum explorationists and researchers working in the South Atlantic will welcome this addition to their libraries.
The printed version of Memoir 73 was the Winner of the 2000 Dott Award for best AAPG Special Publication.”