Identificação de Possíveis Exsudações de Óleo na Bacia do Espírito Santo, utilizando imagens SAR

Abstract

Located in the homonymous state, in southeastern Brazil, the Espirito Santo basin was developed in the context of the Gondwana break-up and the opening of the Atlantic Ocean. Its halokinesis affects sedimentation up to the present and promotes large and complex saline structures. Abrolhos, in the Eocene, is the most expressive volcanism in the basin and may have affected the thermal maturity of the rocks, allowing the generation of oil and gas. The present work aims to locate, recognize and quantify the possible oil sees in the maritime portion of the Espirito Santo Basin, using SAR imagery from the Radarsat-2 and Sentinel-1 satellites. Confirmation its only possible after in situ verification. The database consists of 21 Radarsat-2 scenes, 23 Sentinel-1 scenes, and 101 seismic lines belonging to two 2D seismic projects requested at ANP. After literature review, the selection of SAR images was made based on its basin coverage area. They were prepared in the PCI Geomatics software and interpreted in ESRI/ArcMap, where the extraction of the features took place. Meteorological and oceanographic data, when available, were used to assist interpretation. Later, the presence of structures (faults, fractures, salt domes, etc...) was verified in the seismic lines. After detailed analysis, the obtained data were gathered, aiming to classify the possible seeps found according to the probability of happening. There were 3 parameters, subdivided into criteria, used in the ranking score: SAR (distance of vessels, number of SAR images and feature size), Geological (tectonic domains) and Seismic (distance from seismic lines, presence of structures and, distance from structures). Each criterion received grades ranging from 0.1 to 1.0 (respectively worst and best scenario). The final score is given by the arithmetic mean of the parameters. This allowed the possible seeps to be organized in a ranking. The methodology adopted was successful in identifying 44 promising features in the Espirito Santo basin and another 10 in the northern Campos basin, that need further investigation. Half of the possible seeps found, 27 features, obtained a grade higher than 0.7, which strengthens the idea of being oils seeps. Finally, a map was made, in scale 1:2.000.000, with the location of all possible seeps found.