Major Types Of Deep-Water Reservoirs From The Eastern Brazilian Rift And Passive Margin Basins

Abstract

Turbidites and associated deep-water facies comprise the most important petroleum reservoirs in Brazil. They contain original in place volumes of 57.2 billion bbl of oil, and 27.5 trillion cubic feet of gas, and total reserves of 12.5 billion bbl of oil, and 8.3 trillion cubic feet of gas. Brazilian petroleum-bearing turbidites occur in (1) CarboniferouslPermian, glaciomarine pre-rift (interior cratonic) successions, (2) Neocomian to Aptian, lacustrine rift successions, and (3) Upper Albian to Lower Miocene, marine passive margin successions. Most of the petroleum accumulations are distributed along the eastern Brazilian margin, which tectonic and sedimentary evolution is linked to the Neocomian breakup of Gondwana and the subsequent opening of the South Atlantic Ocean. Turbidites comprise 553 production zones from 171 oil and/or gas fields, mostly concentrated in the Campos, Reconcavo, SergipelAlagoas, and Espirito Santo basins. This paper presents an overview of the sedimentary facies, high-resolution stratigraphy, sandbody geometry, and reservoir heterogeneities of the major types of Brazilian deep-water reservoirs, which include (1) gravel/sand-rich, turbidite channel complexes, (2) trough-confined, gravel/sand-rich turbidite lobes, (3) unconfined, sand-rich turbidite lobes, (4) sand/mud-rich turbidite lobes, (5) gravel/sand-rich turbidite and debrite aprons, (6) deposits of sand-rich, lacustrine density underflows, (7) deposits of sand/mud-rich debris flows, and (8) deposits of sandy bottom currents.