Allseas will upgrade the heavy-lift construction vessel Pioneering Spirit with a new jacket-lifting system, making it capable of removing entire jackets from the sea floor
When the heavy-lift construction vessel Pioneering Spirit commenced operations five years ago, it represented a step change in offshore oil and gas installation and decommissioning projects, with unparalleled single-lift capability. Now Swiss-headquartered owner Allseas is pushing decommissioning technology further by adding a new jacket-lifting system to the world’s largest ship that promises to speed up jacket removals.
Speaking during SMM 2021, Allseas department head, heavy -lift engineering Jos Haarman discussed the company’s single-lift technology for the offshore heavy-lift and decommissioning markets and previewed Pioneering Spirit’s new jacket-lifting system.
Founded as a pipelay contractor in 1985, Allseas evolved beyond its original scope by developing and adding specialised heavy-lift and decommissioning assets to its fleet, according to Mr Haarman. The company’s first vessel was Lorelay, the first pipelay vessel to operate on full dynamic positioning, providing precise positioning and manoeuvring capabilities. Additionally, the vessel’s ship-shape allowed for higher transit speeds and increased storage of pipe, making it less dependent on offshore pipe supply. Built to Lloyd’s Register class, Lorelay has an overall length of 227 m, beam of 26 m and depth of 16 m, with a capacity to store 7,200 tonnes of pipe, and total installed power of 17,760 kW, reaching a maximum speed of 16 knots.
Mr Haarman said Lorelay was representative of the company’s philosophy when it enters an existing market. “We are trying to develop the innovation that’s required to push forward,” said Mr Haarman. Ten years after its introduction into the market, Lorelay set a record in 1996 for deepwater pipeline installation, laying a steel pipe to a depth of 1,645 m in the Gulf of Mexico.
When Pioneering Spirit was delivered by Daewoo Shipbuilding & Marine Engineering’s shipyard in 2014, and later fitted out its topsides-lifting equipment in Rotterdam, it was clear it was no ordinary vessel.
A massive heavy-lift crane vessel, the 382-m Pioneering Spirit is the largest vessel in the world in terms of gross tonnage (403,342 tonnes) and second only in size to Shell’s floating liquefied natural gas production unit Prelude FLNG. A slot that measures 122 m by 59 m between the twin-hulled vessel’s bows enables Pioneering Spirit to move around a platform and lift and transport entire topsides using eight sets of horizontal lifting beams.
This single-lift capability and its ability to lift topsides of 48,000 tonnes and jackets of 20,000 tonnes are what make Pioneering Spirit so exceptional. This single-lift capability sets Pioneering Spirit apart from other heavy-lift vessels.
“There’s little human intervention required, so it reduces the risks involved in typical offshore removal methods”
“We come into a field where we’ve done the preparations before, and we can take up an asset in one go, rather than how the competitors are doing it – piece by piece,” said Mr Haarman, adding, “There are no barges in the field. There’s little human intervention required, so it reduces the risks that are involved in the typical offshore, removal methods.” Additionally, he noted another advantage of the single-lift capability is that the structure can be transported ashore, where all of the labour-intensive work can be accomplished.
New jacket-lifting system
Work is underway to increase Pioneering Spirit’s capabilities to allow it to single lift and transport complete offshore steel jackets weighing 20,000 tonnes from the seafloor, using a new special jacket-lifting system (JLS), located on the vessel’s stern.
How does it work? After the foundation piles of the jacket are cut near the seabed, two 170-m- long main beams of the JLS are raised by an upend system and ballast water. This raises the JLS up off the deck and over the stern of Pioneering Spirit into the water next to the submerged jacket. The vessel is carefully positioned closer to the jacket. Main hoist blocks are lowered from the JLS. Once in position, sling-handling wire is lowered for grommet connection. The grommets are lifted and secured on the main hoist trunnion hooks. Once connected, the jacket is lifted by the main hoist system, and aligned with the JLS beams. Finally, the jacket is tilted from a vertical position to a horizontal position on deck and secured, ready for transport to a shoreside facility for recycling.
Mr Haarman expects the new jacket lifting system will be launched this year.
Complementing the lifting systems is a 5,000-tonne special-purpose crane for additional lifts, such as lighter topsides and jackets, modules and bridges.
“We have a track record building up from 2016 until last year of 12 fully finished projects, lifting close to 200,000, tonnes of decommissioned and installed steel structures,” said Mr Haarman. He expects Allseas’ portfolio of offshore decommissioning and installation projects to grow. “2022 will be a very busy year,” he said.
Competitor Heerema Marine Contractors (HMC) enjoyed a record-breaking year in 2020, removing 85,277 metric tonnes of steel, which was recycled in the Netherlands, the UK and Norway. HMC reported on social media that its DP 3-class heavy-lift vessel Aegir underwent an upgrade in Singapore, increasing its auxiliary capacity to 2,000 metric tonnes and the main hoist to 5,000 metric tonnes.
Designed for offshore heavy lifting, HMC’s semi-submersible crane vessel Sleipnir recently set its new record with a 10,100 single-lift jacket removal. The only LNG dual fuel-powered heavy-lift vessel in operation, Sleipnir along with Thialf were in Rotterdam for general maintenance and to prepare the vessels for shore-power connection. This will allow them both to run on 100% renewable energy when moored Rotterdam.
Veslefrikk decommissioning ahead
Expectations are that both Allseas, HMC and other marine contractors will be busy over the next decade supporting decommissioning platforms and infrastructure projects valued at US$22Bn, according to Wood Mackenzie. One field that will be decommissioned in 2022 is the Veslefrikk field on the Norwegian Continental Shelf (NCS).
When it came on stream in 1989, the Veslefrikk development, based on a floating production unit (FPU), was the first of its kind on the NCS. Now, after more than 30 years on stream and over 400M barrels of oil equivalent (boe) produced, the Veslefrikk partnership plans to shutter the field in H1 2022.
Over the years, the partnership has invested some Nrk20Bn (US$2.4Bn) in Veslefrikk, extending its productive life several times. When the plan for development and production (PDO) was submitted the field was originally expected to be shut down in 2009.
“2022 will be a very busy year”
“Veslefrikk was a technologically pathbreaking development which has paved the way for new, lighter offshore structures after the era of concrete giants in the North Sea,” said Equinor senior vice president, operations west Geir Sørtveit.
The floating unit Veslefrikk B is a semi-submersible production platform tied into the fixed wellhead platform Veslefrikk A. The Veslefrikk development was important to the development of regulations for the use of floating installations.
Veslefrikk B was originally the West Vision drilling rig, owned by Smedvig in Stavanger. The rig was purchased by the then Statoil for conversion to petroleum production, and Smedvig won the contract for staffing maritime crews and drilling services.
Extensive work, several contracts
An environmental impact assessment has been conducted and a decommissioning plan for Veslefrikk was sent to the authorities in H3 2020. The newly established Field Life Extension (FLX) business area has the corporate responsibility for implementing decommissioning projects for Equinor on the NCS.
“As the biggest operator we have much infrastructure that must be gradually decommissioned on the NCS. We have solid project capabilities in the area, and have developed good plans for removing Veslefrikk in a safe and efficient manner,” said Equinor senior vice president for FLX Camilla Salthe.
“Priority number one for a successful removal project is having no injuries, serious incidents, or emissions to the environment,” Ms Salthe emphasised.
Before Veslefrikk B can be brought ashore, wells must be plugged, platform systems must be shut down and cleaned, and oil and gas export pipelines must be cleaned and disconnected. In January, the process of plugging wells began, which is being performed under existing framework contracts, where Archer has the contract for rig operations, and Baker and Ardyne deliver most other drilling and well services. A total of 24 wells will be plugged from the drilling system at Veslefrikk.
The decommissioning plans calls for Veslefrikk B to be towed to shore for dismantling in H3 2022 and Veslefrikk A to be removed in 2025/26.
Three large-size contracts associated with the removal work are scheduled to be awarded in H1 2021. One contract will be awarded for the removal and dismantling of Veslefrikk A, which is an engineering, preparation, removal and disposal (EPRD) contract that covers all work in connection with the removal of the platform and subsequent dismantling and recycling.
A second contract will be awarded for the dismantling and recycling of Veslefrikk B.
A third contract will be awarded for subsea work in connection with export pipeline cleaning and disconnection.
In addition, contracts for the planning, management and implementation of the towing of Veslefrikk B to shore will be established in the same way as in 1999, when Veslefrikk B was at Stord for upgrading.