Aasta Hansteen spar

The Aasta Hansteen spar is a spar gas platform designed by Technip-USA,^[1] currently being built by Hyundai Heavy Industries in South Korea. Once complete it will be transported on its side on board the Dockwise Vanguard to the Aasta Hansteen gas field 300 km off the coast of Norway. The spar will be tethered north of the Arctic Circle using polyester moorings to the seabed 1300m below.^[2] At a height of 193m (of which 170m will be submerged) and diameter of 50m this will be the biggest spar platform ever built. The spar has an innovative fat belly design allowing gas condensed on the platform to be stored in the beneath sea level.

Design

At 193m high it will be the tallest spar ever built. Once on site it will be partially submerged by filling ballast tanks and anchored to the seabed, leaving only the top 23m above the surface. The seabed moorings will be made of polyester in place of the traditional steel tethers, possibly the only spar platform to use polyester.

The Aasta Hansteen spar will export the natural gas from the field through the yet to be build Polarled pipeline to the Nyhamna processing plant on the Norwegian coast.

Aasta Hansteen gas field

Originally called the Luva gas field and later renamed after Aasta Hansteen, it was discovered in 1997 approximately 300 km off the coast of Norway. The field is located north or the Arctic Circle, and is subject to perpetual darkness and sub-zero temperatures in the winter months.

Transport

The Aasta Hansteen spar will be built on its side. Once built it will be skidded on tracks onto the semi-submersible heavy transport ship, Dockwise Vanguard and shipped to Norway. The Vanguard will then be partially submerged allowing the spar to be floated off the ship, the spar's ballast tanks will then be flooded, and it will be anchored to the sea bed.

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