New design of semi-sub floating production unit expands Norwegian firm’s offshore energy offering

September 12, 2025, by Melisa Cavcic

Norway’s specialized marine engineering and design house Sevan Deepwater Technology (Sevan DWT), formerly Sevan SSP, has unveiled a new concept for a semi-submersible floating production unit (FPU) designed for deployment across the offshore energy realm, including the oil and gas arena.

This semi-submersible floating production unit concept expands the Sevan DWT portfolio to entail not only its signature cylindrical hulls but also semi-submersibles. The Norwegian player claims that the FPU is designed for easy scalability and adaptability for multiple projects, ensuring an optimized hull design for all weather conditions and client requirements.

“By expanding into multiple platform solutions, we are better positioned to meet the evolving needs of our clients in the energy-related sectors, including both traditional oil and gas and the growing renewable energy market,” emphasized Sevan.

Sevan’s semi-submersible FPU design; Source: Sevan DWT

With a double symmetric main hull, consisting of a ring pontoon and four vertical, octagonal-shaped columns, the Sevan FPU is said to provide favorable motion characteristics because of its semi-submersible structure.

According to the Norwegian player, the platform maintains a highly sufficient air gap in extreme weather, helping to ensure safe operations and minimize downtime during storms. The semi-taut mooring system has a limited seabed footprint, combining polyester lines with moderate chain sizes.

The mooring system, which draws on extensive experience from previous Sevan circular hull projects, is described as offering a system tailored for efficiency and reliability in deepwater applications.

The use of cassion pumps enables the equipment installed in column void spaces to be kept to a minimum. With no direct seawater inlets in column/pontoons, there is a reduced risk of flooding of these areas.

This comes months after the FPSO Penguins, which is the sixth operating Sevan-designed FPSO and the fourth operating in the UK North Sea, started production at Shell’s Penguins field at 165 meters of water depth northeast of Shetland.

Shell’s new North Sea FPSO brings UK’s oil & gas field back online

Exploration & Production

Discovered in 1974, with oil and gas production between 2003 and 2021, the field has restarted production utilizing the cylindrical Sevan 400 design with a process capacity of 45 kbbld and a storage capacity of 400 kbbls.