Image: SLB OneSubsea
Two SLB OneSubsea™ subsea compressor stations recently came online at Ormen Lange, the second largest gas field in Norway. The subsea compressor stations will help Shell unlock 30–50 billion cubic meters of additional gas reserves for export to Europe, enabling an unprecedented increase in recovery from the field of up to 85%.
The project sets a record for the deepest installation of a subsea compression system ever in water depths more than 900 m below sea level, SLB OneSubsea said in a news announcement. The gas will be delivered to Shell’s Nyhamna gas plant 120 km away — setting a record for the longest step out ever.
About the technology
SLB OneSubsea’s subsea multiphase compressor is an industry-first true subsea wet-gas compressor. Conventional compressors require perfectly dry gas to operate safely and efficiently. OneSubsea’s compression system can operate with the unprocessed multiphase well stream — including condensates, produced water, and mono ethylene glycol (MEG) — with liquid fractions ranging from 0% to 100%. It also tolerates sand and solids.
The Ormen Lange system uses two compression stations, each containing two compression modules. Each compressor can provide up to 50-bar differential pressure, configured in parallel for a large volumetric flow capacity. The 32-MW subsea multiphase compression system will use onshore variable speed drives (VSDs) located 120 km away, eliminating subsea VSDs or topside alternatives to improve project economics.