Client: Fairfield Betula Limited
Location: UK Northern North Sea

Option Development, Comparative Assessment and Environmental Impact Assessment


Fairfield ceased production from its Merlin, Osprey and Dunlin assets in July 2015.  The Merlin and Osprey fields are subsea tie back fields connecting to the Dunlin Alpha platform.  The Dunlin field itself also contains a variety of subsea infrastructure, including links to Thistle, Cormorant and Brent Charlie.


Fairfield awarded Xodus Group with an integrated project scope of work to undertake the following:

›        All subsea engineering for infrastructure requiring full removal (execution statements, cost estimates, schedules)

›        All subsea engineering for infrastructure where options were being carried forward to a comparative assessment (14 comparative assessment decisions comprising over 30 individual options), each with execution statements, cost estimates and schedules

›        Personnel safety risk assessment for all options (including full removal), capturing Potential Loss of Life (PLL) figures for offshore and onshore personnel as well as other users of the sea and legacy risk for any infrastructure decommissioned in situ

›        All environmental and societal input to the comparative assessment, including studies on pipeline cleanliness, commercial fisheries baseline, quality assurance of third party environmental baseline reports, habitat assessment reports and drill cuttings reports, quantification of lifecycle emissions, quantification of noise emissions, and quantification of seabed disturbance

›        Facilitation of the comparative assessment process both internally and with external stakeholders, using Xodus in-house multi-criteria decision analysis software

›        Environmental Impact Assessment - three environmental statements for the subsea infrastructure (due to a need for separate decommissioning programmes) as an output from one over-arching EIA.


The above work was completed ready for submission of the Regulatory approvals documentation at the start of Q2 2017.  In parallel in 2017 Xodus is also supporting the decommissioning planning for the Dunlin Alpha platform including the Concrete Gravity Base Structure (CGBS).  This work involves:


›        Facilitation of the comparative assessment process both internally and with external stakeholders, using Xodus in-house multi-criteria decision analysis software;

›        Studies examining topics such as seabird colonisation of a potential future Navaid, options for the cell contents within the CGBS, options for dealing with marine growth, options for debris and drill cuttings, and a risk assessment for all potential activities;

›        Environmental Impact Assessment.


Value Added:


›        Multi-specialised project team with a single Project Manager and point of contact has yielded significant efficiency through the CA process.

›        Xodus has all required skills, disciplines and capabilities in house.   This has increased consistency as well as reduced Fairfield's technical and procurement burdens (one point of contact for all work, one avenue for data transfer, one weekly progress meeting, one action register, one schedule, etc.).

›        Good relationships with stakeholders, including the Regulatory bodies OGA and BEIS (ODU and EMT) has led to pragmatic discussions on the process and scope of study work.