Decommissioning Insight 2015
7.3 Removal Removal is classified as the removal of topsides, substructures (jackets) and subsea infrastructure and accounts for 18 per cent (£3 billion) of the total forecast decommissioning expenditure on the UKCS from 2015 to 2024. FPSO weights have not been included in this category as they are usually relocated or sold for reuse or recycling. As well as the costs associated with physical removal, this phase also includes expenditure for transportation and onshore load-in, where the structure is transferred to the dock. The most common methods for topside removal are piece-small, reverse installation or single lift. The piece-small method involves dismantling the topside 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 are being designed to lift heavier loads. Earlier this year, Royal Dutch Shell began a public consultation on its plan to remove the first of the Brent platforms in what will be the biggest North Sea decommissioning project to date. Following a 30-day consultation, the decommissioning programme was approved by the UK Government. The 24,200 tonne topside of the Brent Delta platform will be removed by Allseas Group in a single-lift by the Pioneering Spirit heavy-lift vessel. The liftwill be carried out on completion of thorough preparations, including the strengthening of the topside using 200 tonnes of steel, and will be one of the heaviest the North Sea has ever seen. According to Shell, this single-lift technique will substantially reduce the risk, cost and environmental impact of removing the Brent platforms 17 . 7.3.1 Topside Removal Central and Northern North Sea/West of Shetland A total of £1.1 billion is forecast to be spent removing 255 topside modules over the next decade in these regions (see Figure 17 overleaf), with an average topside weight of 13,000 tonnes. Over half (134 modules) of this activity is located in the CNS compared to 80 per cent in the NNS in the 2014 report. This shift is due to the large number of new projects now earmarked for decommissioning in the CNS region, rather than a decrease in forecast activity in the NNS. The near-term forecast for topside removal is similar to the 2014 report, with high levels of activity in 2016. Some of these projects are well under way and the timelines for removal are relatively fixed, although some flexibility is typically built into these contracts. By contrast, activity in the second half of the decade has increased significantly since last year, with nine new platforms entering the survey. Relative to the 2014 report, activity is spread more evenly across the decade. Last year, a peak was forecast in 2020, but this is now spread across multiple years as projects undergo small timeline shifts in response to the market.
17 See www.shell.co.uk/sustainability/decommissioning/brent-field-decommissioning.html
Made with FlippingBook