Equinor boosts subsea compression at the Åsgard gas complex offshore mid-Norway

Equinor has started up Phase 2 of subsea compression at the Åsgard gas-condensate production complex in the Norwegian Sea.

This will help maintain production levels through increasing the pressure in the pipelines between the wells and the Åsgard B semisubmersible platform to compensate for pressure decline in the Mikkel and Midgard reservoirs.

History of Åsgard 

Conventional operations started in 1999 through the Åsgard A platform in 1999, with Åsgard B coming onstream the following year. Phase 1 of Åsgard subsea compression—the first project of its type worldwide—began operating in 2015.

In 2023, the first compressor module was replaced under the Phase 2 development, with a second and final module later added on the Midgard Field in 270 m water depth, 40 km from the Åsgard Field center.

Compressor specs and capabilities

The compressor station weighs 5,100 t, occupies a footprint on the seafloor of 3,300 sq m, and is 26 m tall, making it the largest subsea processing plant installed anywhere, according to Equinor.

Its two identical compressor trains operating in parallel are each powered by a compressor with an electric motor capacity of 11.5 MW. A spare train onshore in Kristiansund allows replacement parts to be shipped out quickly if any technical issues occur.

Various components from the old compression modules were overhauled and reused in the new modules.

Everllence (ex-MAN Energy Solutions) developed and built the new compressors, with Aker Solutions in Egersund constructing the compressor modules. OneSubsea performed the installations.

Installation and testing

TechnipFMC and Ocean Installer conducted the marine Installations in 2023 and 2025, respectively.

Functional testing—full-scale in a pool and with hydrocarbons—took place at Equinor's (K-lab) facility in Kårstø, and the system integration test occurred at Vestbase, Kristiansund.

Results

"The compressor system has produced stably for 10 years with almost 100% uptime,” said Randi Hugdahl, vice president for E&P for Åsgard and Kristin. “The system has so far contributed to increased value creation from the field of about NOK 175 billion." 

Equinor added that in both phases combined, the compressor plants should raise the recovery rate from the Mikkel and Midgard fields to 90%, representing an additional 306 MMboe.

Stakeholders

Licensees of Åsgard are Equinor (operator, 35.01%), Petoro (34.53%), Vår Energi (22.65%) and TotalEnergies EP Norge (7.81%).

Licensees of Mikkel are Equinor (operator, 43.97%), Vår Energi (48.38%) and Repsol Norge (7.65%).