Decommissioning Insight 2019

One hundred and nine substructures are expected to be decommissioned in the UCKS over the next decade, representing over 340,000 tonnes of material. These data exclude concrete gravity-based structures (CGBS). 17 As with topsides, the majority of substructure decommissioning activity is forecast later in the survey period, with 73 per cent of the weight scheduled to be removed from 2024 onwards. Interestingly 2026 — the year with the least number of installations expected to be decommissioned — also happens to be the year with the greatest mass. This is because almost all activity in this year is concentrated in the NNS region, where the water depths are greatest and substructures are the largest. This year has four large NNS Substructures and one substructure in the SNS due to be decommissioned. In a similar vein to the profiles shown in the topsides data, the substructure activity dataset shows a steady and sustainable workload in the nearer term and a less feasible forecast at the tail end of the dataset. The nearer-term data present a more realistic expectation of the supply chain and operators may even have contracted some of this activity. As the activity at the end of the dataset becomes nearer and operators continue to engage with the supply chain, the activity profile will become more sustainable.

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17 Note that under OSPAR Decision 98/3, the largest and oldest and largest substructures may be decommissioned in situ if derogation is justified and granted. Therefore, the actual mass to be removed may, in reality, be lower than that shown in the chart.

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