Less UKCS offshore decommissioning carried out despite spending rise of £1.7bn

OEUK’s annual offshore decommissioning report says £1.7bn was spent on decommissioning in the UK Continental Shelf (UKCS) in 2023, a 6% increase from the previous year, but only 126 wells were decommissioned in 2023, compared to 139 in 2022.

Mark Wilson, OEUK’s HSE & Operations Director, says: ‘In short, the UK has spent more money doing less work in 2023. The macroeconomic factors at play cannot be ignored: cost inflation, political risk and competition for resources have all made it harder to do business.’

Key achievements in 2023 include the removal of over 6,000 tonnes of subsea infrastructure and a forecast 50% increase in well decommissioning activities for 2024.  

Forecast expenditure is expected to reach £24.6bn by 2033, with the removal of over 2,000 wells, 914,000 tonnes of topsides and 508,000 tonnes of substructures expected – or more than 80% of active well stock.  

‘The right support from government is needed if the UK is to become an exemplar of decommissioning and for its sector of the North Sea to thrive. A transparent and pragmatic regulatory regime would oil the machinery and stimulate interest in finding long-term and innovative solutions,’ Wilson adds.  

Final topside load-in completed for Brent field  

Meanwhile, the last and heaviest of the Brent oil and gas field topsides, Brent Charlie, has been successfully skidded on to the quayside at Able Seaton Port near Hartlepool, for decommissioning.  

Brent, one of the largest oil and gas fields in the North Sea, was a Shell-operated field located 186 km north-east of the Shetland Islands.  It was once home to four oil and gas platforms: one jacket-based (Alpha) and three gravity-based (Bravo, Charlie and Delta).  

Allseas used its motion-compensated heavy lift vessel Pioneering Spirit to remove the structure at sea in a single lift and transport it to shallow waters, where the topsides was transferred on to a purpose-built cargo barge. Lifting contractor Mammoet, having already overseen the load-ins of Bravo and Delta, then performed the skidding of the 31,000-tonne topsides on to the quayside.

New database sheds light on subsea well and tree infrastructure

An online database which aims to make subsea well decommissioning more cost-efficient has been launched by the North Sea Transition Authority (NSTA).

The Tree and Wellhead Information for Subsea Tooling (TWIST) database provides access to data on the makeup of well infrastructure, with the aim to help companies better plan their decommissioning projects and quickly locate potentially hard-to-find tools.

The NSTA has developed the pilot version using data on 423 wells provided by operators BP, CNR International, Harbour Energy and TAQA, with input from the Well Decommissioning Steering Group, part of the Wells Task Force.

Operators are legally required to fully decommission and seal their wells after they cease production. In some cases, progress has been slowed as companies struggle with a lack of technical information about well architecture and the availability and accessibility of tools. TWIST looks to address this by displaying verified subsea data. To make tooling easier to find, it also lists the equipment maker and manufacturer lineage.  

First wind decommissioning guidelines

In related news, OEUK has produced a set of guidelines for the removal of offshore wind turbines which have reached the end of their useful life.

The two-year project involved adaptation of the decommissioning experience and know-how gained from removing North Sea oil and gas installations.

The guidelines provide an overview of relevant regulations and best practice for technical design and environmental protection to ensure safe and timely decommissioning in offshore wind.

Ensuring workforce safety, and assessing a turbine’s weight and potential for flotation, as well as safeguarding marine life, are all major challenges at end-of-life operations. OEUK has also published a technical work breakdown structure to help cover these issues.

The changes to the seabed environment are now being closely monitored throughout the lifespan of wind turbines, as these changes will influence decommissioning planning decisions, OEUK has said.