Shell has conducted Comparative Assessments for the Alpha steel jacket, drill cuttings, pipelines, gravity base structures (GBS) and cell contents. The objective of these assessments is to show, on balance, which option provides the best solution.
Comparative Assessment Criteria
In accordance with the requirements of OSPAR Decision 98/3 and the DECC Guidance Notes (issued by regulator the Department for Business, Energy and Industrial Strategy), technically feasible options for the Brent field have been studied and subjected to a formal CA.
Technically feasible options were assessed using the five main Guidance Notes criteria, namely:
We used the advice provided in the Guidance Notes which lists those matters which are to be considered during a CA of feasible management options. These include but are not restricted to:
- Technical and engineering aspects
- Impacts on the marine environment
- Impacts on other environmental compartments
- Consumption of natural resources and energy (and climate change)
- Other consequences to the physical environment
- Impacts on amenities and the activities of communities
- Economic aspects
In line with this guidance, therefore, we assessed each option’s performance by dividing that criterion into more specific sub-criteria. For example, the main criterion ‘Environment’ encompasses both the potential environmental impacts arising during the work programme (which is likely to be on a timescale of a few months) and the potential environmental impact arising from the long-term presence of materials, which is likely to be on a timescale of years. By evaluating these different impacts as separate sub-criteria we were able to properly assess the performance of options in these two measures and examine how the environmental impacts changed with different options.
We decided that ‘Safety’ should be assessed using three sub-criteria, ‘Environmental’ using four sub-criteria and ‘Societal’ using three sub-criteria; the criteria ‘Technical’ and ‘Economic’ were each assessed by one sub-criterion.