Abstract: Fazenda Cedro Field: a Complex Paleogeomorphic Stratigraphic Trap

Lima, Valério Q.; Appi, Ciro J.; Câindido, Aladino - Petrobras/E&P/Cenpes

The Fazenda Cedro oil field is located onshore Espirito Santo Basin, 30 Km south of São Mateus City, in the southeastern portion of Brazilian Atlantic margin (Fig. 1).

The Aptian sedimentary sequence of the Mariricu Formation, in the Espírito Santo Basin, is represented by siliciclastic rocks of Mucuri Member and carbonates/ evaporites of Itaúnas Member. The Albian marine transgressive sedimentary sequence of São Mateus Formation and carbonate platform of Regência Formation form the Barra Nova Group.

During the Late Cretaceous time, several erosive sequence boundaries cut the Barra Nova Group and the upper portion of the Mariricu Formation, producing large and deep incisions (e.g. Regência and Fazenda Cedro canyons). The canyons were filled with turbidite sandstones and deep marine shales of the Urucutuca Formation (Fig. 2).

The Fazenda Cedro oil accumulation is trapped in two distinct stratigraphic units separated by an unconformity. The oil is trapped in a paleogeomorphic high defined by the erosion of Mariricu Formation sandstones on the bottom of the Fazenda Cedro Canyon, as well as in onlapping turbidite sandstones of the canyon-filling section. Therefore, the Mucuri Member and Urucutuca Formation form a unique reservoir with the same oil/water contact, where the resulted entrapment is a combination of paleogeomorphic and stratigraphic features.

Geochemical analyses indicate that Upper Neocomian and Aptian shales of the Mucuri Member of Mariricu Formation are excellent source rocks with total organic carbon (TOC) of 2%.

The hydrocarbon migration process occurred through the fault system and filled the trap. The spill-point, in the westernmost part of the field, is represented by the erosion surface.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil