--> The Pre-Salt Sequence of Ultra-Deep Water Santos Basin: Geological Aspects and Key Factors Controlling the Major Oil Accumulations, Machado, Marco Antonio P.; Moraes, Marcos Francisco B.; Gamboa, Luiz Antonio P.; Gil, João A.; Paula, Lemuel de; Silveira, Desiderio P.; Wolff, Breno, #90100 (2009)

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The Pre-Salt Sequence of Ultra-Deep Water Santos Basin: Geological Aspects and Key Factors Controlling the Major Oil Accumulations

Machado, Marco Antonio P.1
 Moraes, Marcos Francisco B.1
 Gamboa, Luiz Antonio P.1
 Gil, João A.1
 Paula, Lemuel de1
 Silveira, Desiderio P.1
 Wolff, Breno1

1Petrobras, Rio de Janeiro, Brazil.

The new and already productive Pre-Salt Section of the Ultra-Deep Water Region of Santos Basin is situated on the São Paulo Plateau, a major geotectonic feature characterized by an abnormal stretching of the continental crust. The development of this anomaly originated a wide and deep rift section with a set of NE-SW half-graben systems. The geological key factors for the major HC accumulations recently discovered are: (1) a thick early rift section partially known with an uppermost part composed by basalts and organic-rich shales, carbonate, and the so called talc-estevensitic sequence ; (2) deep master faults very active in the early rift and progressively quiescent through late rift and sag phases; (3) Late Barremian and Aptian coquinas/stromatolites reservoirs; (4) a widespread evaporitic sequence of about in situ 2000m of thickness; (5) a relatively thin post-salt sequence with no significant tectonic activity. The interaction of these factors during the geological time was very helpful to the accumulation of giant and super-giant fields. The excellent quality of the 3D seismic data acquired in 2001 (the largest of the world at that time) allowed a detailed interpretation by the Petrobras team resulting in the identification of several prospects in the area. From the base of the Aptian evaporite sequence to the oldest stratigraphic levels, we can recognize three stratigraphic packages: the uppermost sag basin sequence (subdivided in Upper and Lower Sag) separated by a pronounced unconformity from the others two stratigraphic packages, Late and Early Syn-Rift section.

AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil