The Northeastern South American margin is defined by Eastern Venezuelan and Guyana Basins bound to the south by the Guayana Shield and Demerara Plateau. The Margin is emerging as a potential major petroleum province with recent discoveries made in the new play types in Guyana basin with a prolific Cenomanian-Turonian source rock and mostly clastic reservoirs of Cretaceous age. Hydrocarbon production from mostly clastic reservoirs exists in the Eastern Venezuelan Basin onshore for more than 100 years but there was no recent exploration activity offshore. The current production is coming from only 25% of a total area of the Eastern Venezuelan Basin which is geologically connected with Guyana Basin. It is not surprising that 75% of the total onshore and offshore Venezuela remains unexplored because of the political climate in the country.
The country needs to be rebuilt and hydrocarbon resources are important to the financial future of the Venezuela. In this paper the attempt will be made to extend the knowledge from the Guyana basin and from available data in Venezuela into untapped territory of the Venezuelan passive margin. Tectonic and stratigraphic evolution of the Northeastern South American margin during Central Atlantic opening has to be analyzed as a conjugate to the MSGBC (Mauritania, Senegal, Gambia, Guinea Bissau and Guinea Conakry)basins.
Development of the Central Atlantic Margin started with a continental breakup between North America and Africa during Triassic and continued into a Jurassic opening of the Central Atlantic Ocean. The growth of the thick Jurassic carbonate sequences along the passive margin of the opening ocean was due to gradual subsidence of the margin and slow sea level rise during Jurassic and Early Cretaceous, which provided the carbonates with a significant accommodation space. Carbonate buildups were also developed on the volcanic features along the margin and some continued to grow during Lower Cretaceous.
During the early Cretaceous with the active South Atlantic opening and initiation of the Equatorial Atlantic opening, SouthAmerica rotated in respect to Africa producing compression and uplift of the Demerara and Guinea Plateaus. The compressional event is recorded in massiveerosion observed on seismic data available over both plateaus and in the drilled exploration wells. The uplift provided a source for large volumes of the eroded material to be deposited into the basins.Africa and South America separated with the release of the compressional pressure after Late Albian causing the collapse of the edges of the plateaus.
The Northeastern South America was at the center of a contentious tectonic reorganization with oceanic triple junction forming between North America, South America and Africa plates since Jurassic. Evolution of the offshore Northeastern basins of South America as passive margin was modified by the eastward movement of the Caribbean plate creating a diachronous foredeep basins along the northern South America during the Neogene. Orinoco Delta was forming since Late Cretaceous and migrating progressively eastward through time. The present day deposition of Orinoco delta offshore extends toward north covering a significant area of the Southern Caribbean margin and into Atlantic Ocean.
Multiple petroleum systems are documented along the Northeastern South America aging from Paleozoic to Neogene. Applying newplay concepts after acquiring new seismic data and application of emerging technologies for data quality improvement of the current data could open up untapped new opportunities along the margin.
Oral presentation at the 1st HGS/EAGE Conference on Latin America: South American Petroleum Play for Future Decades of the Third Millennium.
Houston, November 19 – 20, 2019