Reservoir Systems of Selected Basins of the South Atlantic
Early Cretaceous rifting of the South Atlantic basin resulted in the development of three unconformity-bound tectono-stratigraphic megasequences that are recognizable in petroliferous basins along the present-day margins of both Brazil and west Africa. These megasequences have been termed nonmarine/synrift, transitional marine, and marine. These megasequences provide a framework for understanding the character and distribution of hydrocarbon reservoirs within the South Atlantic petroleum systems. Hydrocarbons occur in nonmarine and marine stratal packages in both carbonates and siliciclastics. Reservoirs in the marine megasequences contain an estimated 70% of the region's known oil reserves, most of which have been discovered in the last two decades in deep-water fields.
Each reservoir system requires a comprehensive evaluation of depositional systems and diagenetic modification. Deep-water siliciclastic reservoirs are controlled by sediment provenance and transport mechanisms to the deep-water setting and less so by diagenesis. Synrift reservoirs are more affected by diagenesis, requiring detailed petrographic analysis. Carbonate reservoirs of the South Atlantic display the greatest degree of variability thus requiring detailed petrographic work. Our results suggest that the carbonate reservoirs have the most complex diagenetic profiles and must be related to the timing of hydrocarbon migration to better understand charge risk.
Figures & Tables
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.”