The world’s first subsea wet gas compression system is ready to be installed on the seabed and tied back to the Gullfaks C platform, Norwegian oil firm Statoil has announced.
The Gullfalks subsea wet gas compression system is being progressed alongside Statoil's Åsgard subsea gas compression project.
Both are regarded as key stepping stones towards Statoil's subsea factory by 2020 vision, which will enable complete processing systems on the seafloor.
The subsea wet compression system on Gullfaks, developed in collaboration with OneSubsea, will help extract a further 22 MMboe from the Gullfaks South Brent reservoir and extend the field's economic life.
Since October last year, the wet gas compressor station has been through the final system integration tests at Horsøy outside Bergen.
By April, the compressor station will be installed 135m deep on the seabed, 15km from the Gullfaks C platform, on to which power and control modules will be integrated. The package, from OneSubsea consists of a 420-tonne protective structure, a compressor station with two 5MW compressors totaling 650-tonne, and all necessary topside equipment for power supply and control of the plant.
Following its installation, an umbilical will be installed, as well as the modules within the compressor station. Everything will be hooked up to the Gullfaks C platform this summer, with start-up scheduled for this autumn.
“I’m very proud of this project. Subsea compression is a game changer for subsea processing and an important technology to increase recovery and lifetime for gas fields”, says Margareth Øvrum, executive vice president for Technology, Projects and Drilling in Statoil.
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.
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%.
Images:
Top - The Gullfaks wet compression system ready for load at Horsoy out before installation 15km from the Gullfaks C platform.
Second - The OneSubsea multiphase compressor for Gullfaks subsea wet gas compression.
Above - Margareth Øvrum.
Left - The Gullfaks compressor station in a test pit.
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