The world’s first subsea compression station is coming together in Norway— Elaine Maslin looks at the work ahead.
Norway’s subsea laboratory is getting close to producing major results for Statoil and Aker Solutions.
The two firms have been working closely on delivering the world’s first subsea compression project, a key step towards Statoil’s 2020 subsea factory goal.
It is the Åsgard project, due on stream in 2015, and the enormity of the project is now on view in Aker Solution’s Egersund facility near Stavanger.
It is the main subsea compression frame for the NOK16billion Åsgard project. At 74x45x26m, it is big enough to fill Oslo’s Ullevaal Stadion – Norway’s biggest football stadium.
It will house 11 modules, including two 11.5MW compressors, a 235-ton inlet cooler, scrubber, discharge cooler and pump, making up the subsea compression unit.
The project will enable the recovery of an additional 280MMboe from the Midgard and Mikkel satellite reservoirs 40km from the Åsgard B platform, increasing the recovery rate from 60% to 87%. It will also avoid the need for a new large semisubmersible platform. Firms involved in the project include Saipem, for lifting, Allseas, for pipelay using the Solitaire pipelay vessel, Nexans, who are supplying umbilicals, and Technip as the marine contractor. Work on the sea floor pre-installation began last summer. Remote-controlled machines installed a new tie-in point on the Åsgard B production flowline at a water depth of 265m the while the gas was flowing, and without preparing the pipeline in advance.
In July, a new 1000-ton module with power supply (from existing gas turbines) controls, barrier fluid pump and variable speed drives, will be installed on Åsgard A using the Saipem 7000. Over the summer, the main subsea compression and manifold frames, at 1800 tons and 700 tons respectively, will be laid on the seabed.
In September, a pilot compressor will arrive from supplier Man, and a compressor unit will be shipped from Egersund to be tested at Statoil’s K-Lab underwater testing facility. This will both test the unit and help set parameters on the two compressors to be used on the field.
The unit’s pump will be tested at Tranby, Norway, and the control systems have started lengthy testing in Aberdeen, where they were built. Once tested, they will be shipped to Egersund to be brought together and tested in trains during 2014, before being separated again into their modules ready for installation.
Installation will then be carried out through 2014, with each module being slot ted in to its respective frame. Installation will be done by the DP3 North Sea Giant construction vessel. It was built in 2011 and is the largest construction vessel in its class, with over-the-side handling systems, specially designed for the project. It has 2900sq m of deck space and a 400-ton crane.
Next year will also see the installation of the umbilicals, spools, and 22 modules across the field, all connected and ready for production to start at year end or into 1Q 2015.
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