Equinor and partners have begun Phase 2 of the Åsgard Subsea Compression project
Equinor and partners have begun Phase 2 of the Åsgard Subsea Compression project, marking a new milestone in subsea gas recovery technology in the Norwegian Sea
The new development aims to maintain production from the Åsgard and Mikkel fields by increasing pressure in the pipelines between the wells and the Åsgard B platform. This innovative system builds on a decade of successful operation from the world’s first subsea gas compression facility, first brought online in 2015.
“In this project, Equinor, together with partners and suppliers, has further developed and qualified the next generation of compressor modules,” explains Trond Bokn, Equinor’s senior vice president for project development. “The technology allows us to recover more gas from producing fields. Good resource utilisation is important to maintain high and stable production from the Norwegian continental shelf.”
A LEGACY OF INNOVATION
The Åsgard field has been a cornerstone of Norway’s offshore production since its initial development plan was approved in 1996. Production from Åsgard A began in 1999, followed by Åsgard B in 2000. Recognising that reservoir pressure would decline over time, Equinor pursued subsea compression as a way to boost gas recovery without installing additional surface platforms.
When the first Åsgard Subsea Compression (ÅSC) station came on stream in 2015, it represented a world first: gas compression technology deployed directly on the seabed. Located on the Midgard field, 40 kilometres from the Åsgard field centre, the facility operates at a depth of 270 metres.
The subsea station is an engineering feat. Weighing 5,100 tonnes and covering 3,300 square metres, it stands 26 metres high — making it the largest subsea processing plant ever installed. It houses two identical compressor trains powered by 11.5MW electric motors, operating in parallel to ensure reliability. A complete spare compressor train, stored in Kristiansund, enables rapid replacement of components to minimise downtime.
PHASE 2: SUSTAINING PRODUCTION FOR THE NEXT DECADE
Phase 2 involves upgrading and replacing the compressor modules to further enhance efficiency and capacity. The first module was replaced in 2023, and the second and final module has now been installed, again at 270 metres depth.
“The compressor system has produced stably for 10 years with almost 100% uptime,” says Randi Hugdahl, vice president for Exploration and Production for Åsgard and Kristin. “The system has so far contributed to increased value creation from the field of about NOK 175 billion.”
By combining the output of both project phases, the recovery rate from the Mikkel and Midgard fields is expected to rise to an impressive 90%, equivalent to an additional 306 million barrels of oil equivalent.
COLLABORATION AND REUSE
Equinor’s Phase 2 development has relied on close collaboration with key suppliers. The new compressors were developed and delivered by Everllence (formerly MAN Energy Solutions), while the compressor modules were designed and built by OneSubsea AS (formerly Aker Solutions Subsea AS) at Aker’s Egersund yard. TechnipFMC completed the marine installation in 2023, with Ocean Installer to follow
in 2025.
Functional testing, including full-scale trials with hydrocarbons, was carried out at Equinor’s K-lab test facility at Kårstø, and system integration testing took place at Vestbase in Kristiansund.
Sustainability and circularity have also been built into the project. “A number of key components from the old compression modules have been overhauled and reused in the new modules,” notes Bokn. This reuse strategy reduces costs, lowers material demand and extends the operational life of critical subsea assets.
MAXIMISING VALUE FROM MATURE FIELDS
By deploying next-generation compression technology, Equinor and its partners are demonstrating how innovation can extend the life of mature offshore fields while maintaining energy efficiency and environmental responsibility.
As Bokn concludes, “This project showcases how technological development and collaboration across the industry can unlock additional resources and sustain production from the Norwegian continental shelf well into the future.”
