Tectonics and hydrocarbon distribution along the Brazilian South Atlantic margin

Abstract

Abstract Break-up of the Brazilian margin produced a wide variety of structural styles depending on opening kinematics and thermal configuration of the lithosphere. Wide margins developed in Santos and Campos, where stretched continental crust extends for up to 600 km from the shoreline; whereas narrow margins may be only 40 km wide. The wide margins host the largest oil fields, such as those discovered in the Campos Basin. Wide margins have good hydrocarbon potential in the post-rift sequence, but narrow margins probably have the better unknown syn-rift plays which have still to be drilled in deepwater. Little is known of the narrow margins, such as the Jacuípe and Pernambuco-Cabo Basin area, as most of the prospective hydrocarbon structures lie in water depths > 1500 m. Hydrocarbons are hosted by reservoirs ranging from fractured Neocomian volcanics to Miocene turbidites, with over 80% of the reserves trapped in the Campos Basin turbidite sandstones. These sandstones occur as constrained channel-fills on the upper platform and slope, and as unconstrained lobes up to 30 km in long dimension on the mid to lower continental slope which are situated in 500+ m water depths at the present day. The wide margins will continue to be the most productive in Brazil, but deepwater production technology has advanced enough to make the deeper parts of the narrower margins attractive exploration areas.