Vulnerability of Atlantic Equatorial Margin and Caribbean Sea to oil exploration in Northern Brazil

This work is a first, exploratory, risk assessment study for the hydrocarbon exploration in Northern Brazil. Lagrangian particles were simulated using the model OpenDrift, being released in the oil blocks (in the stages of production, exploratory and for sale) of the five basins of the region (Foz do Amazonas, Pará-Maranhão, Barreirinhas, Ceará and Potiguar). The surface dispersion of the particles was realistically simulated during 30 days. Simulation ran once per month for five years. The results show that the time it takes for the particles to cross the Exclusive Economic Zone (EEZ) marine boundary of the first neighbouring country (French Guiana) varies from a few hours or days for the releases at the Foz do Amazonas Basin, one week for Pará-Maranhão (except during austral summer due to strong coastal stranding near the Amazon River mouth) and two weeks to one month for the other basins (during autumn and winter). Only the particles from production blocks of the Potiguar and Ceará basins are unable to reach French Guiana. The Caribbean Sea can be reached by particles from Foz do Amazonas during summer and autumn in two weeks and from Pará-Maranhão in one month during autumn. While presenting inter-annual variability, the area affected by the trajectories is dependent on the release location, the elapsed time since the release and the release season. The dispersion along-coast and the ability to significantly impact the EEZ of neighbouring countries may be diminished by three reasons: i) the North Brazil Current retroflection; ii) high coastal stranding inside the Brazilian EEZ and; iii) release occurs too far from French Guiana. The results of this study contribute to the understanding of the dispersion patterns in the Atlantic Equatorial Margin and the Caribbean Sea. This is paramount for the decision making process, especially considering new oil development regions and the possibility of an oil spill to affect other countries.