Exploratory plays of the Foz do Amazonas Basin, NW portion, in deep and ultra-deep waters, Brazilian Equatorial Margin

Abstract

Abstract A petroleum geology study was carried out at Foz do Amazonas Basin northwest portion, a new exploratory frontier basin on the Brazilian Equatorial Margin. Seismic and well data were interpreted to search similar play of some oil discoveries in correlated basins. The study area is in deep/ultra-deep waters, where the influence of the Amazon Cone is less expressive and 90\xa0km east of Zaedyus oil discovery on Guiana-Suriname Basin. There were interpreted four seismic horizons, four chronostratigraphic intervals, two hypothetical petroleum systems, two exploratory Cretaceous plays, and an estimative of the source rock maturity. The petroleum systems are: Cassipore/Codo–Limoeiro (late Aptian-Late Cretaceous) and Limoeiro–Limoeiro (Cenomanian/Turonian-Late Cretaceous). The top seismic horizons interpreted are Basement, Albian, Cretaceous, and Middle Miocene, determining four chronostratigraphic intervals: Early Cretaceous, Late Cretaceous, Paleocene to Middle Miocene, and Late Miocene to Recent. There were interpreted two Cretaceous plays: Slope to Plain and Deep/Ultra-Deep Waters. The main source rocks are the shales of the Codo Formation (late Aptian) and Limoeiro Formation (Cenomanian-Turonian). The Codo Formation reaches 10% TOC, has Type I kerogen, excellent potential for oil generation, and thermal maturity. The Limoeiro Formation may have 4,4% TOC, Type II kerogen, and very good petroleum potential. The reservoir rocks are Late Cretaceous Limoeiro Formation turbiditic sandstones. The seal rocks are marine shales from Late Cretaceous Limoeiro Formation. The traps are mainly stratigraphic (pinch-out). The migration routes are mainly lateral or, exceptionally, vertical, where the faults are present. The estimated source rock maturity indicates that at least one of them is below the oil window top. It was concluded that there is a great hydrocarbon exploratory potential to this part of the basin, similar to the discoveries that occurred in the correlated basins of the equatorial margins of Africa and South America.