The Sevan design
The Sevan design developed for offshore installations meets the oil and gas industry's long standing challenge for versatility, flexibility, and fast deployment. The Sevan design has proved to be an efficient basis for Floating Production, Storage and Offloading (FPSO) units as well as for deep water Mobile Offshore Drilling Units (MODU). The three Sevan FPSO's currently installed at their respective locations; FPSO Piranema Spirit in Brazil, and FPSO Hummingbird Spirit and FPSO Voyageur Spirit in the North Sea, have demonstrate d to meet these challenges and provide confidence that the Sevan technology will continue to perform successfully also on future developments.
The main components of the Sevan FPSO's and MODU are the cylindrical hull. The FPSOs utilize the hull for cargo storage and segregated ballast tanks as well as for marine and utility systems.
The MODU has mud and drill water storage in the hull as well as cargo and ballast tanks. Pumps and other utility systems related both to the drilling equipment and to the marine systems are located inside the hull. A large moon pool is arranged in the centre of the MODU hull.
The Sevan hull is suitable for operation in water depths ranging from 30 m to more than 3,000 m and Sevan units may operate in both benign and harsh environments. Model tests have been made for the most extreme North Atlantic conditions as well as for the toughest cyclonic conditions with excellent results.
Main features of the design are:
- Circular hull with symmetry of the design
- High capacity for oil storage and deck loads
- Excellent motion characteristics
- No turret or swivel
- A large number of risers may be carried by the FPSOs
- High safety standards
The symmetry of the design and the simplicity of the structural arrangement make the construction of the hull simple and efficient. No special facilities or infrastructure are required, thus standard shipyard facilities existing worldwide are sufficient to construct Sevan units.