With four projects operating and another US$19.2Bn to be decided on this year, floating LNG has emerged as a viable solution for commercialising stranded offshore gas
With four projects operating and another US$19.2Bn to be decided on this year, floating LNG has emerged as a viable solution for commercialising stranded offshore gas
With four projects in operation, floating LNG (FLNG) has come of age as a solution for unlocking stranded offshore gas resources. FLNG vessels facilitate production and offloading of LNG directly onto LNG carriers for distribution, eliminating the need to fabricate and install long pipelines from gas fields to land-based liquefaction plants. Inherently FLNG vessels are engineering marvels, incorporating both liquefaction plant and marine systems, designed and built to operate in a marine environment for decades.
FIDs on awards of some US$19.2Bn of projects involving FLNG vessels and floating production, storage and offloading vessels (FPSOs) are expected to be decided over the next year, according to Westwood Global Energy Group senior analyst Mark Adeosun. Because FLNG vessels are constructed at shipyards, the local labour cost and permitting issues associated with the construction of shore terminals can be avoided. Cost control will weigh heavily on investors’ minds.
Enter Prelude
Located 75 km northeast of Broome in Western Australia in water of 250 m, Shell’s Prelude FLNG is one of the largest and most expensive offshore floating facilities ever built. Originally funded at about US$11Bn in 2011, the Prelude FLNG project faced numerous engineering and fabrication challenges. As a result, Rystad Energy vice president, oil service research Matthew Fitzsimmons, says development costs ballooned to an expected US$15Bn – an increase of more than 36% above budget. Reports now suggest that Prelude cost US$17Bn.
“These overruns caused Shell to cancel an order with Samsung Heavy Industries (SHI) for three FLNG units worth US$4.6Bn in 2016”, says Mr Fitzsimmons. “In essence, these cost overruns prevented Shell from sanctioning several additional FLNG projects”.
In June, Prelude FLNG began producing its first LNG. Knutsen Group’s 173,400 m3 LNG carrier Valencia Knutsen carried the long-anticipated first cargo of LNG to Asian buyers, marking a milestone for the world’s largest floating LNG facility.
Measuring 488 m in length and 74 m in width, Prelude FLNG has the capacity to produce, liquefy, store and offload 3.6 mta of LNG, 400,000 tonnes of liquefied petroleum gas (LPG) and 36,000 barrels per day of condensate at peak production.
The processing and liquefaction of gases and condensate occurs in the vessel’s topsides modules. Shell’s dual mixed refrigerant (DMR) process is used to liquefy the gas. Prelude’s LNG and LPG are offloaded via a side-by-side vessel configuration using cryogenic loading arms. Tankers load condensate from the rear of the facility using a floating hose arrangement.
A key component of Prelude FLNG is its turret mooring system that allows the vessel to “weathervane” around its moorings, keeping the facility on station and limiting excursions to protect its riser-system, which receives gas from the subsea architecture. Sixteen mooring lines secure the Prelude FLNG to anchor points in water of 250 m. With overall dimensions of 30 m in diameter and 94 m in height, the turret mooring system allows the facility to withstand the extreme weather conditions experienced in the North West of Australia, including a 1 in 10,000-year storm – which exceeds a category five cyclone.
“FLNG vessels are engineering marvels, incorporating both liquefaction plant and marine systems”
Specifically designed to allow the facility to remain on station for 25 years in extreme weather conditions, the turret was built by SBM Offshore in five modules that were delivered to SHI for integration into the hull.
Built by a consortium of TechnipFMC and SHI, Prelude FLNG is operated by Shell, along with its joint venture partners Japan’s INPEX, which controls a 17.5% stake, South Korea’s Kogas, a 10% interest and Taiwan’s Oversea Petroleum and Investment Corporation (OPIC), 5%.
FLNG speeds LNG production in Malaysia
FLNG technology was utilised by Malaysia energy company Petronas to produce LNG just three days after receiving natural gas from the Kebabangan cluster field in Malaysia.
Moored in 120 m of water 90 km offshore Sabah, Petronas floating LNG Satu (PFLNG Satu) had been repositioned from the Kumang cluster field offshore Sarawak in March.
The first gas from the field was sent to the PFLNG Satu through the vessel’s turret system via a 5 km flexible pipeline. As part of a series of start-up activities, the natural gas was chilled using a dual nitrogen cycle liquefaction process, producing the first LNG three days later. The first LNG cargo delivery from the new field is expected in June.
Able to operate in water of 70 to 200 m with a processing capacity of 1.2 mta, PFLNG Satu was designed and built by a consortium of TechnipFMC and South Korea’s Daewoo Shipbuilding & Marine Engineering (DSME). PFLNG Satu can store up to 177,000 m3 of LNG in eight membrane LNG storage tanks engineered by GTT and 20,000 m3 of condensate in two below-deck tanks.
First ultra-deepwater FLNG
To be moored in almost 10 times the water depth as Prelude, Eni’s Coral Sul FLNG will be the world’s first ultra-deepwater floating FLNG when it is commissioned in the Area 4 block offshore Mozambique in East Africa.
In water of 2,000 m, Coral Sul will be the first ultra-deepwater FLNG (image: Eni)
In 2012, Eni discovered enormous gas reserves off Mozambique’s coast in the Coral field, located in Area 4 in the Rovuma Basin, containing approximately 450Bn m3 of gas.
To build the vessel, Eni tapped an international consortium of companies: France’s TechnipFMC, Japan’s JGC and SHI, which will be responsible for the hull, gas production equipment, risers and flowlines. US-based Baker Hughes, a GE company (BHGE), is responsible for the subsea production systems, Norway’s Aker for the umbilicals and Italy’s Saipem for the wells.
A first for Africa, the Coral Sul FLNG vessel will moor in water of more than 2,000 m. Expected to produce 3.4 mta of LNG, the FLNG vessel is being built to Lloyd’s Register class and will be 430 m long, 66 m wide, and will have a design life of 25 years.
“The FLNG is the best solution possible, both from a technical and production point of view, as well as in terms of the environmental impact,” explains Coral FLNG project development director Stefano Rovelli. “The field is quite far from the coast, and the seabed has a canyon that is up to 13,000 m wide and up to 300 m deep, which makes it difficult to lay pipes to transport the gas to the shore. With an FLNG, the project’s footprint is minimal, limited to the underwater area where we will install three manifolds, the moorings for the vessel and the flexible lines for connection to the FLNG.”
The FLNG will produce, liquefy and store the natural gas at sea. Subsea equipment, such as manifolds, subsea trees and flexible risers will bring the gas to the surface from pockets under the seabed.
“The FLNG is the best solution possible, both from a technical and production point of view, as well as in terms of the environmental impact”
Among the near-shore FLNG developments is the Phase 1 development of BP’s Greater Tortue/Ahmeyim field, located offshore West Africa near the Mauritania-Senegal maritime border.
Singapore’s Keppel Shipyard, a subsidiary of Keppel Offshore & Marine, will convert the 125,000 m3 LNG carrier Gimi with a Moss-type cargo containment system into the FLNG for the project. The shipyard will supply design, detailed engineering and procurement of the marine systems, as well as conversion-related construction services. Delivery of the vessel is expected in H1 2022.
The project will be similar to Keppel’s conversion of the world’s first FLNG vessel, Hilli Episeyo, which was delivered to Golar LNG for work offshore Kribi, Cameroon.
Gimi MS Corporation is 70% owned by Golar LNG and 30% by First FLNG Holdings Pte, an indirect subsidiary of Singapore’s Keppel Corporation Limited held through Keppel Capital Holdings Pte.
First FLNG in Americas
Argentina is now an LNG exporting nation, following the commissioning of the first chilled cargo from Tango FLNG, the first floating LNG vessel in the Americas.
Nicolas Saverys-led Exmar reported performance acceptance tests have been successful, and the first cargo of about 25,000 m3 has been offloaded and will be exported out of Argentina.
For Argentina, Tango FLNG allows for the country to capitalise on the vast shale gas reserves of Vaca Muerta field, among the world’s largest at an estimated 308Tn ft3.
Under an agreement between Exmar and Argentinian energy company YPF, Tango FLNG will spend the next 10 years moored in Bahia Blanca, Argentina. With a length overall of 144 m, beam of 32 m, draught of 5.4 m and capacity of 16,100 m3, Tango FLNG will produce approximately 0.5 mta of LNG.
The start-up of the barge-based Tango FLNG was performed in rapid fashion, with the contract signing in November 2018 and delivery acceptance of the floating unit in Bahia Blanca in February 2019.
“For Exmar, the successful performance test in Bahia Blanca confirms the technical capabilities of the Tango FLNG”, says Exmar chief executive Nicolas Saverys.
US-based engineering firm Black & Veatch used its Prico single-mixed refrigerant loop liquefaction technology to complete its guaranteed performance testing aboard Tango FLNG (ex Caribbean FLNG).
FLNG barge concept gets AiP
South Korea’s Hyundai Heavy Industries (HHI) has received Approval in Principle from class society DNV GL for a design based on the feasibility of constructing a jetty-moored, near-shore FLNG barge using standard shipbuilding rules and techniques.
“The FLNG market is beginning to emerge, and near-shore projects are expected to be at the forefront of these developments”, says HHI general manager Simon Lee. “Our design offers lower production costs, reduces time to production, and improves environmental performance” he adds.
“Floating solutions which can be constructed at a shipyard, such as HHI’s concept, could provide the LNG industry with flexible and cost-efficient solutions,” says DNV GL technical director newbuilding, offshore classification Mike Brogan. “These concepts could be particularly useful in areas with land-based gas resources, where onshore construction is not feasible or desirable,” he explains.
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