The deal means the Abo FPSO will still be afloat 40 years after the vessel left a Japanese shipyard as a crude oil tanker.
Options for a further seven year have also been agreed that could keep the Abo FPSO in employment until the end of 2023.
The deal is with Nigerian Agip Exploration, an affiliate of ENI the Italian oil company.
The Abo FPSO is the former 134,000-dwt tanker Grey Warrior (built 1976) converted in 2003 by Keppel Shipyard in Singapore.
