Estratigrafia de sequências da seção compreendida entre o Neoalbiano ao Mesoeoceno da Sub-Bacia de Mundaú, Bacia do Ceará, com ênfase aos plays exploratórios

Abstract

The Ceará Basin is located at the east portion of the Brazilian Equatorial Margin, and it is subdivided from west to east into four sub-basins: Piauí-Camocim, Acaraú, Icaraí and Mundaú, the latter being the target of this study. The section between the late Albian to the middle Eocene, on that Sub-Basin, is characterized by the Paracuru-Ubarana play, with turbidite reservoirs, like 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 sequence stratigraphy 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 cycles which, together with seismic interpretation, through the recognition of reflector terminations, indicated the positioning of chronostratigraphic surfaces. Along with the use of attributes, that analysis resulted in the individualization of six depositional sequences, according with the transgressive-regressive stratigraphic model. Those sequences were identified both in the shelf portion and in deep waters. Moreover, this work allowed the identification of turbidite plays (Paracuru-Ubarana) in deep waters, which their formation is related to the genesis of submarine fans system rich in sand and mud, deposited by low density currents. Thus, this study is important in the context of the Brazilian Equatorial Margin and their African conjugate one, with regard for analogues to reservoirs of the same age in producing basins on the Brazilian Eastern Margin, as well as for the application of high-resolution sequence stratigraphy in reservoir studies.