Challenge
DNO’s Schooner and Ketch fields in the Southern North Sea comprised normally unmanned installations operated and maintained on a campaign basis by offshore intervention teams. As the fields progressed into decommissioning, DNO required a flexible and cost-effective operating model capable of maintaining safe Duty Holder responsibilities while reducing the fixed cost base and enabling decommissioning activities to progress efficiently.
Solution
DNO appointed THREE60 Energy to provide Duty Holder Operations & Maintenance services alongside integrated integrity, engineering, procurement, construction and decommissioning support.
The operating model was delivered through THREE60’s Aberdeen-based onshore team, supported by multidisciplinary engineering capability and the company’s wider Technical Advisory Network. THREE60 assumed responsibility for the associated management systems and emergency response arrangements, establishing a lean operating model proportionate to the requirements of normally unmanned assets progressing through decommissioning.
The flexible approach also allowed well P&A and removal activities to be undertaken opportunistically, aligning offshore campaigns and resources to reduce unnecessary expenditure while maintaining safe operational control.
Result
THREE60 successfully completed the Duty Holder transition in Q1 2021, assuming operational control of the fields at the end of March.
The new operating model delivered an approximately 30% reduction in operating costs while providing the flexibility required to progress decommissioning activities. The Ketch well P&A programme and topsides decommissioning were subsequently completed, followed by completion of the Schooner programme in 2023.
The project demonstrates THREE60’s ability to take responsibility for assets through the transition from late-life operations into decommissioning, integrating Duty Holder, engineering, well P&A and removal activities within a flexible lifecycle delivery model.
