UK-based oil and gas company Spirit Energy has completed a $55 million (£40 million) decommissioning campaign in the UK North Sea, plugging and abandoning three subsea wells and removing more than 234 tonnes of subsea infrastructure.
The campaign, carried out between April and July in the UK Southern North Sea, covered the Seven Seas and Grove G5 production wells and the Grove Deep exploration well.
Spirit worked with more than 30 UK supply chain companies, including DeepOcean and Well-Safe, combining multiple decommissioning activities within a single campaign.
DeepOcean's construction support vessel Edda Freya carried out enabling works at the Seven Seas and Grove G5 sites. At Seven Seas, about 60 km off the East Yorkshire coast, the vessel removed a 100-tonne wellhead protection structure. At Grove G5, 131 km east of the Norfolk coast, remotely operated vehicle operations were used to disconnect subsea infrastructure and prepare the well for further decommissioning.
Well-Safe's jack-up rig Well-Safe Protector was subsequently deployed at both locations to carry out reservoir abandonment activities.
The Seven Seas and Grove G5 wells produced a combined 56 billion cubic feet of gas during their operational lives. Grove G5 produced from 2008 to 2019, while Seven Seas produced from 2012 until production ended in 2024.
The campaign involved more than 114,000 hours of work, with multiple vessels, including tugs, a rig and a construction support vessel, operating alongside ROVs and existing offshore assets.
"Some of the biggest challenges involved working with older infrastructure, alongside the Southern North Sea’s notoriously unpredictable weather. It’s why close working across all of Spirit’s teams and with our contracting companies has been absolutely critical to this project's success.
"We've had multiple vessels in the water at any one time, including tugs, a rig, a construction support vessel and ROVs, all while having to work together along with existing assets that are still in the field. Frequent and clear communication between onshore and offshore means that decisions can be made quickly leading to a safe and efficient campaign,” said Ceri Wheaton, Spirit's Decommissioning Manager.
Spirit pointed out that 100% of the recovered subsea materials are to be reused or recycled in UK yards.
"Safely and efficiently decommissioning offshore infrastructure when it cannot be repurposed is a key focus for our industry, and our support for the NSTA’s decommissioning charter reflects our commitment to doing this work safely and efficiently.
"It’s particularly pleasing that we are on course to recycle or reuse 100 per cent of the subsea materials recovered with the work to be carried out in UK yards. The campaign has been a great example of how operators and contracting companies can work together, and its success is testament to the hard work and expertise that exists right across the UK supply chain,” added Matt Browell-Hook, Spirit's Director of Energy Transition, Decommissioning and Projects.