Technip and Aker Solutions have recently announced they both have been awarded front-end engineering design (FEED) contracts by Statoil ASA for the development of the Aasta Hansteen (formerly named Luva) Spar platform. This facility will be the largest of it’s kind with a total hull length of 193 meters and a draft of 170 meters.
The Aasta Hansteen is destined for the high seas offshore Norway, at a water depth of approximately 1,300 meters (4,265 feet) and will be the first Spar platform on the Norwegian continental shelf (NCS). This platform will also the world’s first Spar platform with condensate storage capacity.
Aker Solutions’ announced that they will incorporate a condensate storage feature called a ‘belly.’ The ‘belly’ refers to the increased diameter on part of the circular shaped hull, where the condensate storage tanks are located. This gives the Aker Solutions’ Belly-Spar its characteristic shape.
“The Belly-Spar concept is a result of the innovative spirit and culture among our engineers, who have come up with the right solutions for the challenging conditions on the Aasta Hansteen field,” says Valborg Lundegaard, head of Engineering business area in Aker Solutions.
The mooring system for Aasta Hansteen Spar platform consists of a set of polyester lines. “There are currently no installations on the NCS with polyester mooring. Aasta Hansteen may be the first, and it will definitely be operating in the deepest water,” says Henning Ã˜stvig.
In talking with Technip the other day, they weren’t able to give us specific details on any of the features of their spar design, however it’s being designed with lessons learned from the Perdido Spar in the Gulf of Mexico, an ultra-deep water platform they designed for Shell a few years ago, while also incorporating features that will allow it to produce in the harsh weather offshore Norway.
Giving us some perspective on harsh environment design considerations for such a platform, ABS’ Director of Offshore Technology, Sudheer Chand comments:
A facility built for a harsh environment such as offshore Norway will have a number of unique features. In particular, the structural design may need to be robust enough to deal with the occasional iceflow, and the materials used must be able to maintain their strength and elasticity under very cold conditions. The machinery and working spaces, must be shielded from the weather and must be able to operate under extreme conditions. In addition, designs must be scrutinized so that water is not allowed to collect and freeze in crevices or tight spaces.
Both Technip and Aker plan to include steel catenary production risers in their designs.
The field was discovered in 1997 and lies 300km offshore in the VÃ¸ring area. The license partners are Statoil (75%), ExxonMobil (15%) and ConocoPhillips (10%). Together with Haklang and Snefrid South, it is estimated to contain recoverable gas reserves of 40-60 billion standard cubic metres (scm).