Statoil installed the first subsea wet gas compressor in the world at the Gullfaks C platform in the North Sea after a successful offshore campaign (see video below).
Image: Seaway Heavy Lifting's Oleg Strashnov carrying the protective structure.
The 420-tonne protective structure and compressor station were installed in 135m deep water 16km from Gullfaks C in early May by Seaway Heavy Lifting's heavy lift vessel Oleg Strashnov.
On 26 June the 2 x 5MW compressor station and cooling modules, weighing 650-tonne, were delivered from OneSubsea's facility at Horsoy, near Bergen, were lowered into place from Subsea 7's Seven Viking offshore construction vessel.
The plant will be tied back and hooked up to the Gullfaks C platform in the late summer and autumn, before entering the final testing and preparation phase with start-up scheduled for Q4 this year.
Image: One of the modules being loaded at OneSubea's Horsoy facility.
“This is the first compressor of its kind in the world. It is a milestone, not just towards the compressor start-up, but also for Statoil’s subsea factory visions,” says Steinar Konradsen, owner representative for the project.
“Subsea wet gas compression is a game-changer for subsea processing, and an important technology to increase recovery also on other fields.”
Subsea wet gas compression at Gullfaks C will add 22 MMboe to the field and extend production by about two years, says Statoil.
The Gullfaks technology solution is a wet gas compressor which does not require any treatment of the well stream before compression.
Image: Offshore installation of the compressor station frame.
Subsea compression provides a greater effect than a conventional topside compressor. In addition the platform avoids extra weight and space required by a topside compression module.
According to Statoil, subsea gas compression represents a considerable technological leap forward. When the reservoir pressure falls below a critical level, subsea wet gas compression will help maintain high gas production.
Image: Offshore module installation by Subsea 7.
Compression on the seabed provides greater effect than a conventional topside compressor. In addition, the platform avoids the extra weight and space required by a topside compression module.
The advantage of a wet gas compression facility is that it does not require any treatment of the well stream before compression. This makes for smaller modules and simpler construction on the seabed.
Thanks to this technology, combined with conventional low-pressure production in a later phase, the gas recovery rate from Gullfaks South Brent may be increased from 62% to 74%.
Image: A view from beneath the waves during installation.
Statoil is currently implementing two subsea compression projects at Åsgard and Gullfaks on the Norwegian continental shelf (NCS) together with its license partners. Statoil says the projects represent important pieces of the jigsaw puzzle of designing the subsea factories of the future.
Watch the installation video:
All images and video from Statoil.
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