Estudo geológico/estrutural de parte da porção on shore da bacia do Ceará

Abstract

Ceará Basin is located at namesake Brazilian state's continental shelf. Its origin is associated to the opening process of the Atlantic Ocean, so it is dated as being from the aptian age from the Cretaceous period. Because Ceará Basin is genetically associated with other important Brazilian basins such as Recôncavo Basin, at the state of Bahia, Santos Basin, at the state of São Paulo, and Campos Basin, at the state of Rio de Janeiro, it has aroused the curiosity about its potential for oil and gas. Therefore, for a best characterization of the area and evaluation of its potential for trapping hydrocarbons in the basin's continental portion, it was made a geological map in the scale of 1:50.000, focusing the structural aspects. For aggregate the knowledge about the structural features, it was done a revaluation of geophysical data previously acquired along the state of Ceará's west coast, between the municipalities of Pecém and Paracuru. It was applied the vertical electrical soundings (VES') as part of the Dunas project, created and developed by the Companhia de Gestão de Recursos Hídricos (Cogerh) in 2011. Quaternary unconsolidated sediments at the northern and northeastern portion overlapping alluvial conglomerates and the Barreiras group rocks mostly compose the geology in the study area. The basement appears only in the Southern part of the study area, displaying a low compositional variety, but many textural features, such as the grain size that increases toward the South. The most frequent lithology are foliated trachytes striking NW which are found at abandoned quarries dose to drainage systems. The VES' revaluation allows an approach about the basement's depth, and the geoeletrical profiles showed ups and downs in the basement that likely represent a series of discontinuities striking NE-SW. This structural framework suggests the existence of hydrocarbons traps, however, further geological and geophysical research are necessary for description about this oil and gas system.