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Offshore Support Journal

Offshore Support Journal

FLNG projects create further demand for specialised service vessels

Mon 26 Jun 2017

FLNG projects create further demand for specialised service vessels
KT Maritime’s infield support vessels can operate in ‘rotoring’ or indirect towing mode, if required

Supporting the growing number of floating liquefied natural gas projects remains the preserve of a relatively small number of vessel owners with experience of working with LNG

Although the floating liquefied natural gas (FLNG) market has not developed quite as quickly as once hoped, key projects such as Prelude are due to come on stream in the near future, and others such as Eni’s US$8 billion deal to develop the Coral South gas field offshore Mozambique have recently been given the green light with a final investment decision.

Coral FLNG is the first new production project to reach a final investment decision in 2017, but there are others in the pipeline. Analysts such as Wood Mackenzie say they expect the Fortuna FLNG project could get the go-ahead soon, noting that Ophir Energy has signed an umbrella agreement setting out the legal and fiscal framework for the Fortuna project, putting the Equatorial Guinea offshore production project on course to reach a final investment decision.

Although it didn’t lead the race to develop the world’s first FLNG vessel, Petronas was first across the finish line with FLNG Satu, which has begun to produce LNG from the Kanowit gas field off Malaysia’s Borneo coast, supported by marine units from the Petronas fleet. The next FLNG vessel to enter into service will be Golar’s FLNG Hilli, a converted LNG carrier, in Cameroon in late 2017/early 2018. Prelude is currently expected to follow it later in 2018. FLNG Hilli is reportedly due to leave Keppel shipyard in Singapore by the end of July this year.

“LNG project sanctions over the last two years have been few and far between,” Wood Mackenzie said. “This reflects the prevailing oversupply in the LNG market.” However, as it noted, the two projects it expects to be sanctioned this year, Coral and Fortuna, are both FLNG projects. “This highlights a positive shift in industry perception toward the FLNG concept,” said Wood Mackenzie. Majors Eni, Shell, Exxon and recently BP have all now endorsed the floating LNG concept. “With stranded gas resources suited to FLNG elsewhere in Africa, Mozambique offers Eni an ideal regime to test this new approach.”

Operators are attracted to FLNG compared to onshore alternatives because FLNG facilities are seen as being more secure, can have shorter lead times, remove the need for a long pipeline to shore and offer a potentially lower-cost alternative to monetising stranded gas fields. This means that, although there are inherent risks, FLNG is undoubtedly a prospective market that in the long run is poised to drive many future gas developments.

For the time being, supporting FLNG projects is expected to be the preserve of a small number of extremely specialised vessel owners – among them KT Maritime and Smit Lamnalco – and will be conducted by highly specialised, special purpose offshore tugs. It differs significantly from the kind of support duties provides by platform supply vessels and anchor handlers in the offshore oil and gas sector, although there are similarities, such as the need to provide safety standby services. Supporting FLNG units is also very different from harbour towage operations, not least because it takes place offshore and in remote areas where redundancy is of great importance and logistic support is challenging.

As Andy Brown, group business development manager at Smit Lamnalco explained, bidding for an FLNG support requirement also requires a high level of expertise and in-depth assessment of the environmental conditions prevailing at the location at which the FLNG unit will be moored before the concept of operations and scope of work for the support vessel provider can be defined and optimum number and type of vessels required can be identified. Given the often remote nature of the location, an assessment of shoreside support, local content requirements and training are also essential. More and more, he says, marine companies such as Smit Lamnalco specialising in this kind of work are providing consultancy services to the companies developing FLNG projects prior to bidding for the provision of support services.

Due to start in 2017, Shell’s Prelude scheme is one of the industry’s first FLNG projects. The 488 m long floating unit is to be stationed 230 km off the Australian coast in 240 m of water for 25 years and will operate continuously, in terms of both gas processing and the loading of LNG, liquefied petroleum gas (LPG) and condensate tankers. Vessel assist duties will be the responsibility of three powerful tugs, highly specialised units that Shell has designated as infield support vessels (ISVs). The ISVs will remain on station at Prelude and only return to their home port of Broome occasionally for maintenance. Once the Prelude FLNG facility is operational, all of the ISVs will be permanently assigned to it.

Perth-based KT Maritime Services Australia, a joint venture between Kotug International and Teekay Shipping Australia, is providing Prelude’s three 42 m, 100-tonne bollard pull ISVs. The tugs are of Robert Allan’s advanced rotor tug ART 100-42 design by ASL Marine Holdings. The ISVs will feature the RAstar hullform as well as the three separate azimuth propulsion units – two astern and one amidships – that comprise the rotor tug power system technology pioneered by Kotug.

The ISVs,  due to mobilise in July 2017, will also provide Prelude with an important emergency response capability. In the event of an emergency on board the FLNG, personnel will be able to make their way safely to temporary refuge sites on the vessel via multiple escape routes forward and aft. They can then be evacuated from the facility in a controlled manner using helicopters, freefall lifeboats and integrated chute-based liferafts. Once evacuated, they can be recovered by the ISVs. Each of these tugs will be able to accommodate 85 people in such situations.

Osman Munir, KT Maritime's director commercial/Kotug's chief commercial officer, told OSJ that the company sees the specialised ISVs as having primary roles and secondary roles. Among the primary roles are assisting LNG carriers approaching the FLNG and when LNG and LPG is offloaded via a side-by-side vessel configuration using specially designed cryogenic loading arms. Among the secondary operations that the ISVs will be responsible for are safety standby, evacuation, personnel transfer and surveillance.

Mr Munir explained that the LNG tankers will have to berth alongside the FLNG’s manifolds to take on the LNG produced on board. Although this is an operation similar to normal berthing of LNG tankers, these are usually carried out in sheltered waters. Offshore, the impact of environmental conditions and waves can be a challenge. In the standard procedure developed for this kind of operation, an amended push-pull method has been developed.

Two of the ISVs, sailing stern first, establish a towline connection, one at the bow and one at the stern. The tanker is brought alongside the FLNG, and the tugs move into the side of the tanker in order to push it against the side of the FLNG. Pushing against the side with standard stern drive tugs can only be done in good weather conditions. Maintaining an acceptable footprint with a stern drive tug would be impossible in adverse conditions, with the increased risk of damage to the tug’s fender and the LNG carrier’s hull. In contrast, with the rotor tug, if the significant wave height increases, the unique propulsion configuration enables it to maintain position whilst applying force against the hull of the tanker in the designated area.

For work in increased wave heights, Kotug has also proposed an alternative procedure, known as ‘rotoring’ or indirect towing, which will be used when required on the Prelude contract. This particular technique sees the rotor tugs assisting the LNG carrier on a short wire length. The tugs stay connected centre forward and centre aft on a short wire, and the tugs then push against the short tow line. They do not need to be repositioned to transfer forces onto the tanker. This alternative procedure mitigates the risk of damaging the hull of the LNG carrier and is only possible with the unique rotor tug configuration.


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