Dunlin FAQs

Decommissioning commences with a process by which options for the physical removal and disposal of facilities/structures at the end of their working life are comparatively assessed.  Subsequently, a plan of action is developed by the operator, approved by government and thereafter implemented. The overall timescale for decommissioning activity is several years, as it needs to take into account many diverse factors and involves many stakeholders.

A combination of flow rates, prevailing oil price, the need for major investment in subsea infrastructure and conductor integrity issues, meant that decommissioning was the appropriate course of action.  

This is a multi-year project that has been subject to a robust planning process. The project’s key objectives are the safe and cost-effective execution of activities in full compliance with the approved Decommissioning Programme(s), namely: the plugging and abandonment of the Dunlin Alpha platform wells; Dunlin Alpha topsides removal and derogation of the Dunlin concrete gravity base and legs to the approved state; the plugging and abandonment of the Osprey and Merlin subsea wells; the removal and/or decommissioning in-situ of the Dunlin, Osprey and Merlin subsea infrastructure; the onshore recycling / disposal of topsides; and development of an agreed plan for the management of post-removal ongoing obligations.

In recognition of our Decommissioning Provisioning obligations, we began the long-term planning for the Dunlin decommissioning in 2010 although at that time the plan was to invest to extend the operational life of the Greater Dunlin Area fields and facilities to beyond 2025.  Following cessation of production at the facilities in June 2015, a detailed planning process for the decommissioning of the facilities was commenced.  We recognised this to be a complex and technically challenging undertaking that will involve a multi-phase, multi-year process.

The overall cost of executing the Decommissioning Programmes will only be known when all relevant activity is closed out and legacy monitoring plans confirmed. Fairfield Energy is required to report the costs to both the Offshore Petroleum Regulator for Environment and Decommissioning, and the North Sea Transition Authority.

Following regulatory approval, the Osprey, Merlin and Dunlin subsea infrastructure has been decommissioned as follows:

• For the Osprey Field, all surface laid pipelines have been removed, while the Osprey Bundle system has been decommissioned in situ and made safe for other users of the sea.
• For the Merlin Field, the Merlin water injection pipeline has been fully removed, while the Merlin oil production pipeline remains trenched and buried under the seabed.
• For Dunlin Field subsea infrastructure, the Dunlin Fuel Gas Import (DFGI) pipeline remains trenched and buried under the seabed.

Operators have to submit detailed programmes for the decommissioning of offshore installations and pipelines which are considered on a case-by-case basis by the Offshore Decommissioning Unit (ODU) of the Offshore Petroleum Regulator for Environment and Decommissioning (part of the Department for Energy Security and Net Zero – ‘DESNZ’ – formerly ), which is responsible for ensuring compliance with the Petroleum Act.

The UK’s international obligations on decommissioning are governed principally by the 1992 Convention for the Protection of the Marine Environment of the North East Atlantic (OSPAR Convention). DESNZ is the competent authority on decommissioning in the UK for OSPAR purposes. In July 1998, the OSPAR Commission adopted a binding Decision (OSPAR Decision 98/3) to ban the disposal of offshore installations at sea, but considers derogation cases where full removal is determined to be impracticable.

In order to ensure full compliance from a regulatory perspective, we have sought early engagement with the relevant regulatory bodies. A key engagement was held in September 2015 with the then Oil and Gas Authority (now the North Sea Transition Authority), and Department of Energy and Climate Change (DECC – now DESNZ) Environmental Management Team, Environmental Inspectorate and ODU. The product of this engagement was an agreed roadmap for regulatory approvals which has served as a key reference throughout the progression of the project.

Comparative Assessment (CA) formed a core part of the overall decommissioning planning and approval process for all elements of the Dunlin Alpha installation and tied-back infrastructure. The CA process used Multi Criteria Decision Analysis (MCDA) pairwise software and was aligned with the Oil & Gas UK guidelines for Comparative Assessment in Decommissioning Programmes (2015) and the Regulatory Guidance Notes for the Decommissioning of Offshore Oil and Gas Installations and Pipelines under the Petroleum Act 1998 (2011).

We scoped all the associated infrastructure into logical groupings, with decommissioning options for each group identified, assessed, ranked and screened. The feasible options were then carried through to formal CA workshops involving external stakeholders and regulatory observers. The CA process used the five standard assessment criteria of Safety, Environment, Technical, Societal and Economic and sub-criteria to compare the relative merits of each option. The assessment criteria were equally weighted to balance and represent the views of the associated key stakeholders, with the Economic criterion used only to determine between outcomes where other criteria were equal, rather than as a driver.

An independent consultancy was employed to facilitate the CA process.

The Offshore Petroleum Regulator for Environment and Decommissioning (part of the UK Government’s Department for Energy Security and Net Zero) is the competent authority on offshore decommissioning in UK waters. Further information on the process for the decommissioning programmes and their contents can be found in the latest version of the Offshore Oil and Gas Decommissioning Guidance Notes (November 2018).