Challenge
With a mature North Sea development no longer economically viable, a UKCS operator required an optimised decommissioning strategy covering removal of the FPSO from station and subsequent decommissioning of the associated subsea infrastructure. The operator required an integrated plan that established the technical approach, schedule and cost of the programme while addressing the complex interfaces between subsea infrastructure, topsides facilities, marine operations and regulatory requirements.
Solution
THREE60 was engaged from the outset to support development of the decommissioning programme, including recovery methodologies, cost estimates and compilation of the overall execution plan. Following selection of the preferred approach, THREE60’s role expanded to deliver the supporting engineering and technical studies required to progress towards execution.
The multidisciplinary scope included flushing and pigging studies, subsea equipment recovery planning, waste estimation and permits and consents support. Close interfaces were also maintained with topsides facilities and marine teams, ensuring offshore activities were coordinated as part of an integrated decommissioning programme.
Result
The decommissioning programme received regulatory approval, enabling the project to progress into offshore execution. Isolation, flushing and disconnection activities were subsequently progressed in preparation for subsea recovery, with the wider recovery programme phased across subsequent offshore campaigns.
THREE60’s scope was delivered in line with the agreed programme and budget, providing the operator with continuity from early decommissioning planning and regulatory approval through engineering and execution support.
