Oil spill modeling off the Brazilian eastern coast: the effect of tidal currents on oil fate

Abstract

This study presents a comparative analysis of several theoretical oil spill scenarios occurring in the vicinity of the Abrolhos Reefs, a preservation area located off the Brazilian east coast. The following petroleum blocks were considered in the study: BM-CUM-1, BM-CUM-2, J-M-259 and ES-M-418, to verify the effect of the tide on the oil spreading on the continental shelf in the eastern Brazilian. The probabilistic oil spill simulations were carried out for 30 days and considered an oil of intermediate API (American Petroleum Institute) type. The simulations were performed by the OSCAR (Oil Spill Contingency and Response) model which was fed by synoptic wind data and hydrodynamic data simulated by the POM (Princeton Ocean Model) model. Two distinct seasonal scenarios were studied: the austral winter and the austral summer of 1989 and the results were discussed in terms of seasonal variability caused by the winter/summer winds and differences in mesoscale instabilities. The effect caused by tidal currents was analyzed through the comparison between simulations with and without the tides. It was concluded that the tide strongly influenced the probabilistic results of fate of oil in the spill scenarios. Many factors have influenced this fate of the spreading of oil in the absence of supra-inertial processes, such as the location of the spill, the behavior of the prevailing winds and tides in the region. The tide absence in the hydrodynamic data did not found the worst case scenarios of the spill in simulations in blocks BM-CUM-1, BM-CUM-2 and J-M-259, mainly in summer with use of intermediate oil, underestimating the real scenarios of spill.