When a pipeline, cable or umbilical has reached the end of its useful economic life, it must be decommissioned. In the UK, pipeline decommissioning is regulated by OPRED under national regulations. To determine the optimum pipeline decommissioning option, owners are required to carry out a Comparative Assessment, taking account of the safety, environmental impact, societal impact, technical feasibility and economics of each feasible option. There are currently no international regulations for decommissioning disused pipelines.
Decommissioning options available for pipelines are as follows:
• Leave in place
• Full removal
• Trench and bury
• Rock cover
• Hybrid options encompassing elements of the above
Outcomes from the CA are embodied in the Decommissioning Programme, which undergoes public consultation before approval by the Secretary of State for Business, Energy and Industrial Strategy. Once the Decommissioning Programme is approved, it is up to the owner to determine the optimum way of delivering the agreed scope. Offshore decommissioning activities are performed by offshore construction contractors with specialist equipment to safely carry out the required activities.