Spirit Energy has completed a £40 million decommissioning campaign in the UK Southern North Sea, plugging and abandoning three subsea wells and removing more than 234 tonnes of subsea infrastructure.
The work was carried out between April and July and covered the Seven Seas and Grove G5 production wells and the Grove Deep exploration well. More than 30 UK supply chain companies participated, including DeepOcean and Well-Safe.
DeepOcean deployed the construction support vessel Edda Freya for enabling works at Seven Seas and Grove G5. At Seven Seas, approximately 60 km off the East Yorkshire coast, the vessel removed a 100 t wellhead protection structure.
Edda Freya then moved to Grove G5, 131 km east of the Norfolk coast, where remotely operated vehicles were used to disconnect subsea infrastructure and prepare the well for the next phase of decommissioning.
Well-Safe subsequently deployed the jack-up rig Well-Safe Protector to Seven Seas and Grove G5 for reservoir abandonment activities. The rig returned to Aberdeen after completing the work.
Seven Seas and Grove G5 produced a combined 56 billion cubic feet of gas during their operating lives. Grove G5 produced from 2008 to 2019, while Seven Seas was in production from 2012 until 2024.
The campaign involved more than 114,000 hours of work and required the coordination of tugs, a rig, a construction support vessel, remotely operated vehicles and offshore assets already operating in the field.
Ceri Wheaton, Spirit Energy’s Decommissioning Manager, said older infrastructure and weather conditions in the Southern North Sea were among the operational challenges. Coordination between offshore and onshore teams and contractors was required while several vessels and offshore assets were operating at the same time.
The campaign incorporated practices set out in the North Sea Transition Authority’s Decommissioning Charter, which Spirit Energy and 16 other UK operators have committed to support.
Spirit Energy said all subsea materials recovered from the campaign are expected to be reused or recycled at UK yards.
