Drilling contractor Transocean and vessel owner Eneti (Seajacks) have announced plans to form a joint venture (JV) for offshore wind foundation installation. Under the JV, there is the expectation that at least two, perhaps more, drillships from Transocean’s fleet will be converted into dedicated heavy-lift floaters.
With its Seajacks fleet, Eneti is currently purely focused on the jackup vessel market. Much of its experience has been in the O&M sector within Europe, predominantly in the North Sea area, and worldwide turbine installation campaigns. While Eneti has also previously performed foundation installation campaigns, it will undoubtedly benefit from having access to a foundation installation fleet as this type of operation is not the main purpose of jackups.
Demand for floating installation vessels will continue to rise
Indeed, the announcement comes at a time when the addition of further floating heavy-lift vessels will be most welcome in the market. Offshore wind demand will rise exponentially in the coming years and, at present, there is a distinct lack of heavy-lift vessel availability - a source of anxiety to developers globally.
The use of heavy-lift floaters is of key importance in installing the XXL monopile foundations that the industry is poised to use in the majority of projects during the second half of this decade. These foundations will then support the “next-gen” turbine models with nominal capacities ranging from 15 to 20 MW. Current demand forecasts state that almost 10,000 XXL monopiles (those over 2,000t) will be installed between 2025 and 2030. The vessel supply as it stands will fall well short of that target.
So far, the supply needs in foundation installation have been through two main methods:
- Wind Turbine Installation Vessels (WTIVs): these jackups are mainly used in installing turbines and are often employed to install lighter foundations.
- Floaters: these are not capable of installing turbines. This fleet mainly consists of ageing vessels (15-to-20 years old) which were initially built for the Oil and Gas (O&G) industry such as platform installation vessels, semisubs and pipelayers.
Gradually, however, a new wind-dedicated heavy-lift fleet has been emerging. Rather than using O&G assets in offshore wind campaigns, the new fleet involves purpose-built units.
The main characteristics of this new fleet include:
- A robust, extra-large deck which is capable of carrying as many monopiles as possible in one trip.
- A crane of at least 3,000mT, often more than 5,000mT, which is capable of installing XXL monopiles.
The wind installation floating fleet
The first vessel in the new wind-dedicated heavy-lift fleet was the Bokalift 1. Converted in 2017, and delivered in 2018 to join the active fleet, the Bokalift 1 was initially one of Boskalis’ semi-submersible heavy transportation vessels. Huisman China performed the conversion and fitted the ship with a 2,800mT crane. In the five years since its delivery, the Bokalift 1 has undertaken several foundation installation campaigns but has also worked in the O&G industry at ConocoPhillips’ Viking decommissioning programme.
With Bokalift 1 a success story, Boskalis aimed to repeat the process with a second unit. The vessel owner purchased the ex-Transocean drillship GSF Jack Ryan and fitted it with an even larger 4,000mT crane during its conversion at Drydocks World Dubai in 2021. The 2000-built drillship had been cold-stacked for several years prior to conversion after which it became the Bokalift 2. Bokalift 2 has been exclusively used for offshore wind assignments and has a packed schedule of commitments lined up.
Meanwhile, orders of the purpose-built, rather than converted, wind-dedicated heavy-lift fleet are also picking up the pace.
Subsea 7 is building the yet-to-be-delivered Alfa Lift, Jan De Nul has ordered Les Alizes (also yet-to-be-delivered) and DEME received its flagship Orion a year late because of a 5,000 mT crane collapse incident at the Liebherr yard in May 2020. DEME is also waiting on Green Jade: the first HLV to be built in Taiwan.
Due to the long timelines involved in building these vessels, there may be several advantages to converting an existing hull in comparison to ordering new vessels. The success Boskalis’ has had within its own fleet is a testament to this fact.
Which Transocean vessels best fit the bill?
Transocean currently has eight cold-stacked drillships within its fleet. The SHI-built former 7th Generation Ocean Rig units: Ocean Rig Mylos (2013-built), Deepwater Athena ( 2014-built) and Ocean Rig Apollo (2015-built) and the DSME-built 6th Generation units: Discoverer Americas (2009-built), Deepwater Champion (2011-built), Discoverer Clear Leader (2009-built), Discoverer India (2010-built) and Discoverer Luanda (2010-built).
The exact rigs to be used in the JV have not yet been specified, however, the JV states that “upgrades to the vessels would include a 5,200t crane and are expected to provide them with the capability to carry up to six 3,500t monopile foundations with 12m diameter.”
When compared, it is clear that the current Transocean cold-stacked fleet is, on average, more profiled and thinner than the broad heavy-lift vessels of the existing wind fleet. Having a wide deck is key when transporting and upending transversally-loaded monopiles. Despite this, the deck sizes are comparable, therefore, almost all of the eight units would be suitable on this basis alone.
Hull re-inforcement and shape would also be a key factor in selecting the best fit-for-purpose drillships for conversion. The hull will need to be strong enough to support pile upending frames/pile grippers to allow monopile handling. Hull shape will remain also a key factor to ensure best stability during lifting operations.
While it is likely that between two and five rigs would be selected for the conversion programme, it will be of benefit to both the rig market and the wind market. For wind, it will help to meet the exponential rise in demand expected in the latter half of the decade, while for the rig market, it will help in reducing the number of long-term cold-stacked units in the fleet.
If successful, the Transocean-Eneti JV could bridge the gap between the drilling industry and the offshore wind installation industry with more drilling contractors converting their cold-stacked assets by partnering with installation contractors. This would go even further in helping with the foundation installation demand crunch the offshore wind industry is facing.
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