Client: Premier Oil
Location: UK Central North Sea


Premier Oil requested Xodus Group to conduct a comparative assessment for decommissioning of the subsea assets across the Balmoral Area, or B-Block.  The B-Block consists of seven fields, the Premier operated Balmoral, Glamis, Sterling, Brenda and Nicol as well as two further third party fields.

The scope included additional technical studies as determined during the comparative assessment.

The comparative assessment and supporting studies allowed Premier Oil to determine the preferred options for decommissioning of the subsea infrastructure, as well as the FPV mooring system.



Comparative Assessment (CA):

The CA followed the OGUK guidelines commencing with Scoping. 

  • The scoping phase defined the CA boundaries, assessed the infrastructure and arranged it into equipment groups of similar attributes for efficacy of the process.
  • The screening phase then considered all feasible decommissioning options by group and screened out the least preferred using the main criteria as defined by OGUK, Safety, Environment, Technical, Societal and Economic.
  • Studies were conducted to detail out the attributes of the remaining options in preparation for evaluation.
  • Xodus Group applied a multi-criteria decision analysis (MCDA) using a pair-wise assessment to compare options.  From this process recommended options emerged.
  • The findings were presented by Xodus and Premier to statutory stakeholders for further review and approval ahead of formal submission of the findings for public consultation.
  • Rigid Pipeline Integrity Assessment
  • Decommissioning Method Statements and Cost Estimates
  • Energy and Emissions Assessments
  • Underwater Noise Assessment
  • Geotechnical Assessment

Supporting Studies:

To provide the appropriate quantitative and qualitative data for evaluation options Xodus conducted a number of technical, safety and environmental studies.


Value Added:

Use of Xodus’ MCDA tool was well received both internal and external stakeholders.  Xodus’ tool uses an Analytical Hierarchy Process with expressive terms in place of numerical values, thereby allowing for a qualitatively means of scoring options against each other.  The process allows stakeholders them to engage meaningfully in each decision.


Xodus Group has a wide range of technical expertise in-house to support multi-discipline studies.