GDF Suez takes over as operator of Gjøa when the field comes onstream in October. The project comprises a semisubmersible platform with subsea tiebacks, and is also expected to be a hub in the future. Meg Chesshyre opens this month's Scandinavian offshore review with a look at Norway's largest current industrial project.
Development of Gja, including the Vega and Vega South fields, has involved a total investment of NKr40 billion. The field, expected to remain in production until 2024, will have 23 wells, a capacity of 87,000b/d of oil and 17mmcm/d of gas.
Gas export is via Flags to St Fergus in the UK, and oil export via TOR II to Mongstad. The operations centre will be in Stavanger, and there will be a base for logistics at Florø, which already supplies Statoil's Snorre field.
Gja has estimated recoverable reserves of 82 million bbls of oil and condensate and 40bcm of gas and output is expected to peak at 50,000b/d of liquids and 10mmcm/d of gas. In addition, the Vega satellite field has estimated reserves of 26 million bbls of condensate and 18bcm of gas.
It will be the first semisubmersible to be powered by electricity from the mainland, reducing carbon dioxide emissions by an estimated 210,000t/yr. It will also be equipped with a gas turbine for emergencies.
Gja, discovered in 1989, is in licence PL153 and has been in the GDF Suez portfolio from 2003. The owners in the licence are: Statoil (development operator) 20%, GDF Suez (production operator) 30%, Petoro 30%, Shell 12% and RWE Dea 8%.
GDF Suez has a clear growth strategy for a long-time perspective in Norway. Its capex 2001-09 was NKr18 billion and the company says it intends to invest a further NKr20 billion over the next five years. It already has stakes in three non-operated producing fields – Njord in the Norwegian Sea, Fram in the North Sea and Snøhvit in the Barents Sea and in the Melkoya LNG facilities, and plans to drill an exploration well as operator in the Barents Sea next year.
The Gja semi was towed out to the field from Aker Stord's yard in mid-June. Gja is one of the largest ongoing field development projects in the North Sea with a topsides weight of 22,000t and a hull dry weight of 15,000t. Aker Solutions signed, engineered and assembled the platform, which will connect to five subsea templates.
The Gja deck measures 110m long and 85m wide. Its highest point is the flare tower at 143m. In total, more than 500 Aker Solutions engineers have been mobilised to design the platform, from Oslo as well as Mumbai in India. During the final assembly at Stord, peak manning reached 3000.
Key deliveries have also been made by other Aker Solutions locations in Norway, including Egersund, Verdal, Moss and Pusnes, with Aker Marine Contractors taking care of mooring system installation, transportation and installation of the Gja platform.
Statoil's vice president for the Gja field development, Kjetel Digre admits that work on Gja had not been without unexpected obstacles. An unusually long and snow-laden winter created a number of challenges for the project. And when spring finally arrived the platform tow had to be postponed, as a systematic review had revealed that some minor modifications had to be carried out to the platform hull.
‘We have tackled a number of unforeseen hitches on the Gja project, states Digre.
‘So far we have solved all the challenges without delaying the planned start-up in the fourth quarter of 2010. This says a lot about what our project people are made of and it also speaks volumes about the need for having access to a competent specialist network, both in Statoil and at our suppliers.' OE
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