Decommissioning Insight 2015

DECOMMISSIONING INSIGHT 2015

7.3.2 Substructure Removal The removal method will depend on the type and weight of the substructure to be cut and lifted. The substructures to be removed in the SNS and Irish Sea regions are shallow water jackets that typically weigh less than 2,000 tonnes and are usually deployed in water depths of 55 metres or less so they may use a single-lift removal method. For larger structures (barge-launched and some self-floaters), the jacket may be cut into smaller sections in situ and removed in segments. The ability to cut large and often complex steel sections in an offshore environment is one of the key challenges during this stage of the decommissioning process. These more complex projects are typically located in the CNS and NNS/WofS areas. In 2009, the removal of BP’s North West Hutton jacket in the NNS region involved 248 cuts using three different methods. The decommissioning sector continues to innovate in developing existing and new cutting technology. Within the survey timeframe, substructure removal activity in the CNS and NNS/WofS regions is forecast to begin in 2018, peaking in 2024 (see Figure 19). Compared to the 2014 report, activity has shifted slightly later and there has also been a large increase towards the end of the survey timeframe, with substructure removal forecast for six projects in 2024. Between 2018 and 2024, an average of 15,000 tonnes is anticipated to be removed each year. Substructure removal activity in the SNS and Irish Sea largely mirrors that seen for topside removal in these regions, with 2017 and 2020 the years of greatest activity. Compared to the 2014 report, shifts in project schedules have brought the peak year of activity forward from 2020 to 2017. Between 2016 and 2024, an average of just over 5,100 tonnes is forecast to be removed each year. Figure 19: Forecast for Substructure (Jacket) Weight Removal

35,000

Increased Uncertainty in Forecasts

Central and Northern North Sea (Lift-Installed, Barge-Launched and Self-Floater)

30,000

Southern North Sea and Irish Sea (Shallow Water)

25,000

20,000

15,000

Tonnes to be Removed

10,000

5,000

0

2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

Source: Oil & Gas UK

Weight (Tonnes) 2015 to 2024

Total Expenditure 2015 to 2024

Substructure Removal

105,100 46,200

£588million £226million

Central and Northern North Sea Southern North Sea and Irish Sea

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