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Seismo-stratigraphy and 3-D Petroleum System Modelling of the Colorado Basin, Offshore Argentina

Anka, Zahie *1; Loegering, Markus 1; Rodriguez, Jorge 2; Marchal, Denis 2; diPrimio, Rolando 1; Vallejo, Eduardo 2
(1) Section 4.3. Organic Geochemistry, GFZ German Research Centre for Geosciences, Potsdam, Germany.
(2) Petrobras Argentina S.A, Buenos Aires, Argentina.

The analysis of a dense 2D seismic reflection dataset and data from 12 exploration wells, allowed us to identify the main syn- and post-rift seismo-stratigraphic sequences and build a 3D petroleum system model calibrated not only to thermal data, but also to present-day hydrocarbon-leakage indicators observed on the continental shelf and slope of the Colorado Basin.

The sequence maps (twt) show a shifting configuration from the break-up unconformity (130 Ma) to the present-day seafloor. The break-up unconformity displays a central EW-elongated graben, which prevails on the overlying sequences up to the Miocene. Sedimentation during the basin sag phase (Aptian to Campanian) is mainly located in the central part of the basin, while there is a discrete eastward depocentre migration during the Paleocene. An important transgression, accompanied by aggradation and decrease in sedimentation rate, sets on during the Eocene. A dramatic increase in sediment supply takes place from the Oligocene up to the Present, driving a depocentre migration to the outer parts of the basin.

The potential hydrocarbon migration pathways predicted by the 3D basin-wide model have been calibrated to the presence of interpreted seabed pockmarks depressions located close to an array of submarine channels on the slope of the basin. Results from this calibrated model indicate that although syn-rift and early Cretaceous source rocks (SR) intervals would be depleted in the central areas of the basin, it may exist an active kitchen from the Aptian SR, which is probably feeding the interpreted pockmarks on the slope of the basin.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California