To discuss how to responsibly conduct a Comparative Assessment/Decommissioning Options Assessment (CA/DOA) that is fit for purpose and is scientifically sound and robust, allowing for the study to be successfully validated by an external third party.

The most stringent International Best Practice Guidelines should be applied to all CAs. Decommissioning activity, internationally, is under public scrutiny and in many regions, in the very early stages of development. Application of industry proven approaches is essential to successful decommissioning planning.

Such documentation is important to demonstrate that the potential impacts (e.g. safety, social, environmental) that may arise from decommissioning activities have either been removed or are reduced to As Low As Reasonably Practicable (ALARP).

Methods, Procedures, Process

Statements and decisions made in the CA should be justifiable to scientifically sound supporting information. Contributing information shall include, but is not limited to, Quantitative Risk Assessments (QRAs) such as Potential Loss of Life, Individual Risk Per Annum and Fatal Accident Rate.

Good understanding of the condition of the facilities to be removed through asset integrity assessments and ROV inspection studies is essential. Furthermore, it is equally important that there is good understanding of the nature and condition of the seabed, from which the facilities, are to be removed. In addition to understanding what sensitive species may be present to properly inform management measures.

For environmentally sensitive cases or when Rigs to Reef is considered as an option, it is recommended that dedicated side studies are performed using industry proven techniques such as the Net Environmental Benefit Analysis (NEBA).

Once all the necessary documentation is gathered, the CA can take into consideration supporting information to appropriately inform the decommissioning options to be considered; the sub-criteria to be assessed and the rankings and weightings applied. It may be necessary to apply assumptions in lieu of the availability and/or transparency of data. Assumptions should be based on informed judgement and must be scientifically sound and justifiable to Project activities or to other similar activities conducted in a similar environment.

Results, Observations, Conclusions

Strategic partnerships should be developed to ensure that the necessary skill sets and capabilities are available to appropriately conduct the CA. Impacts to Project cost, schedule and public perception are to note just a few of the consequences of an improperly applied assessment process.

A thorough and comprehensive approach to decommissioning planning and options assessment allows for the development of a Flagship Decommissioning Project. Careful consideration of international Best Practice procedures and the incorporation of scientifically sound supporting data, provides a demonstrably robust assessment process. In environments where national legislation and national experience is lacking, operators can look to other international examples of successfully and responsibly applied decommissioning programmes for guidance.

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