Sequence Stratigraphy of the upper Albian to middle Eocene of the Mundaú Sub-
Basin, Ceará Basin, with emphasis on exploratory plays
Sequence Stratigraphy; Mundaú Sub-Basin; Turbidite Reservoirs; Exploratory Plays.
The Ceará Basin is located at the east portion of the Brazilian Equatorial Margin, and it covers, geographically, the states of Ceará, Piauí and part of Maranhão. The basin is subdivided from west to east into four sub-basins: Piauí-Camocim, Acaraú, Icaraí and Mundaú, the latter being the study region. The Mundaú Sub-Basin covers an area of approximately 12,000 km2 and it has three tectonosedimentary stages: Rift, Post-Rift and Drift. The section that includes the Lower Cretaceous, Paleocene and Eocene is within the Drift stage, which is lithostratigraphically represented by the Ubarana, Tibau and Guamaré formations. That interval has oil potential indicated by the Ubarana – Upper Cretaceous play, characterized by turbidite reservoirs, similar to important discoveries at the African Margin, such as the Jubilee field, and at the Equatorial Margin in offshore fields of Guyana and Suriname. For this study, concepts of low and high resolution stratigraphic analysis were used in data from eight exploration wells and ten 2D seismic lines, located from the most proximal portions, in shallow waters, to the deep water region. The analysis of the wells allowed the characterization of lithofacies and transgression/regression cycles which, together with seismic analysis, through the recognition of reflector terminations, seismic facies and unconformities, resulted in the individualization of six depositional sequences. Furthermore, this analysis allowed the identification of turbidite plays in deep waters, that are important in the context of the Brazilian Equatorial Margin and the African conjugate, as analogues to reservoirs of the same age in producing basins on the Eastern Margin.