Seismic Stratigraphy of Pre-Salt in the Southernmost of Santos Basin

Márcia K. Karam, Roberto Porto, and Makoto Saito
E&P, Queiroz Galvão Óleo & Gás, Rio de Janeiro, Brazil

The sin-rift sediments comprise important source rocks and their recognition and distribution at seismic data are an essential fact to understand the petroleum systems of sedimentary basins of the South Atlantic continental margin.

This work discusses a generalized procedure for a seismic stratigraphic study in an area located in the southernmost of Santos Basin near to Cavalo Marinho, Caravela, Coral, Estrela do Mar and Tubarão fields. The sedimentary section analysed comprises Guaratiba lithostratigraphic Formation.

The pre-salt section in this area is best imaged on seismic data because of the absence of thick overlying salt package in contrast with other areas where the salt causes distortion difficulting the interpretation.

The evaluation of Pre-Salt in the Southernmost of Santos Basin using 2D and 3D seismic data reveals that there are three seismic stratigraphic sequences compounded by (1) a lower volcanic rocks sequence, (2) an intermediate sequence where half grabens predominate, related to an intense period of tectonic activity and (3) the upper sequence characterized by tectonic quiescence identified as Sag Phase. It is suggested that the first sequence would be related to rifting events (Rift Sequence) and the second would belong to Transitional Sequence including the upper part of Guaratiba Formation. In this last sequence began the thermal subsidence.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas