U.S. environmentalists warn that plans by Brazil’s state oil company Petrobras to become the first company to use converted oil tankers as oil extraction and storage rigs in the Gulf of Mexico pose serious oil-spill risks. In April or May, Petrobras is slated to be the first oil company to use floating production, storage and offloading (FPSO) vessels in the Gulf. FPSOs are oil tankers retrofitted as production rigs. They are anchored on site and connected by semi-flexible steel tubes, called risers, to manifolds on the seafloor that collect oil from multiple nearby wells. FPSOs can process and store up to 500,000 barrels of oil and regularly (at one- to two-week intervals) transfer the oil to other tankers for delivery to coastal... [Log in to read more]