Decommissioning Insight 2016 - Oil & Gas UK

Figure 15: Forecast Length of Pipelines for ‘Making Safe’ on the Norwegian Continental Shelf

1

140

Increased Uncertainty in Forecasts

120

2

100

3

80

60

4

Kilometres of Pipeline

40

20

5

0

2016 2017 2018 2019 2020 2021 2022 2023 2024 2025

Source: Oil & Gas UK

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Pipeline ‘Making Safe’ 2016 to 2025 (Kilometres)

Norwegian North Sea

354

Norwegian Sea

No activity No activity

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Barents Sea

5.3 Topside and Substructure Removal Removal is classified as the removal of topsides, substructures (jackets) and subsea infrastructure. The weights of FPSOs have not been included in this category as they are usually relocated or sold for reuse or recycling. The ability to cut large and often complex steel sections in an offshore environment is one of the key challenges during this stage of decommissioning. The availability of heavy lift vessels, the development and use of new technology for removing installations, and the capacity of disposal sites will all affect how decommissioning on different projects is implemented. The removal method deployed will depend on the type and weight of the topside and substructure and will be determined through comparative assessment of the available options.

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The most common methods for topside removal are piece-small, reverse installation or single-lift.

• The piece-small method involves dismantling the topside and using onshore demolition techniques to produce small, manageable pieces that can be transported onshore.

• For reverse installation, the topside modules are lifted separately onto a transportation barge or the deck of the crane vessel before being taken onshore.

• The single-lift method involves removing the topside in one piece and may involve extra engineering work to reinforce the topside in preparation for removal. As technology moves on to keep up with the decommissioning market, vessels such as the Pioneering Spirit are being designed to lift heavier loads 17 .

17 See www.allseas.com/equipment/pioneering-spirit

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