Cautiously optimistic, Adnan Zainal Abidin and Wan Badrul Hisham sit in Petronas' London office as thousands of miles away in a South Korean dockyard, 125,000 tons of metal is expensively becoming the world's first Floating Liquid Natural Gas (FLNG) vessel.
The two engineers from Malaysia's national oil and gas company are an integral part of the management team for the ambitious project. FLNG Satu is both a new type of Liquid Natural Gas (LNG) plant for the oil and gas sector and a new type of ship for the maritime sector. It's engineering on a massive scale – a 380m long and 60m wide vessel – packed tight with all the equipment needed to produce, store and distribute natural gas extracted from offshore fields miles out from shore in situ.
The project to build and operate the first FLNG vessel is daunting. Natural gas would normally be piped onshore to a large plant to be liquefied, stored and then shipped around the world in tankers. The challenge of putting all of those processes onboard a boat is more than considerable. The reward though, is the exploitation of gas fields that would otherwise go undeveloped because they are too small or too far from shore. Abidin, who is vice president of global LNG projects for Petronas, says: “FLNG provides an avenue for us to monetise stranded gas fields, and fields that are not big enough to lay a pipeline to shore for. It's a new way for us to develop these fields, or they wouldn't see the light of day.
“But being the trailblazer is not easy. We recognise that everybody is watching. At the end of the day we want a product that we can rely on.”
FLNG Satu is 365m long and weighs 125,000 tons
Abidin describes FLNG Satu as “basically a LNG plant on top of a boat, with a storage tank in the hull”. In terms of functionality it is probably most similar to an FPSO (Floating Prodution Storage Offloading unit). The plant and equipment topside and throughout the vessel is arranged into 20 modules. There are seven on top, from a pretreatment module through to a liquefaction module. Each module is built offsite, craned onto the vessel at the dockyard and installed. Six of FLNG Satu's topside modules have so far been lifted on to the deck and the last topside module should be on the ship by the end of January.
FLNG Satu is expected to leave South Korea by the end of this year and will start producing gas at a “stranded” field 180 km off the coast of the state of Sarawak in Eastern Malaysia before April next year. It will produce around 1.2 million tons of LNG a year for at least 20 years, around 230 million tonnes a day. A second FLNG is also planned, which will have a slightly larger capacity of 1.5 million tonnes per year and work another field further offshore of the Malaysian state of Sabah. FLNG Dua will be ready by 2018 and be able to operate in deeper water – up to 1200m compared to FLNG Satu's 200m.
After Petronas' upstream team drills the Sarawak field and performs the subsea operations, the FLNG will be towed to the site - the vessel has no propulsion system because it will hardly ever move. It will then be moored and the riser connected to its turret. Gas will travel up to be treated in the modular plant, where contaminants such as water, CO2 and sulphur, which would freeze later in the process, are removed. The gas is then chilled and liquefied at temperatures as cold as -162 degrees C. The LNG is then stored and transferred directly to tankers from the vessel itself, instead of being loaded at a jetty onshore.
Developing the processes and selecting the right plant and equipment to cope with the motions of the sea was the most difficult challenge of FLNG Satu's design. The equipment on board FLNG Satu differs in size and weight to what would be used onshore because on top of a ship space, access and weight is limited. Abidin says: “Building a plant on a boat has different aspects to consider than onshore. The rolling motion and pitch of the vessel has to be taken into account. It also determines the choice of processing equipment. It's a technical challenge in itself because you want to minimise the weight in a compact area. So you have to select equipment that serves your purpose in terms of size, but also in terms of reliability and robustness in terms of operation and maintainability.”
Abidin says: “We made a decision that most of our drivers are aero-derivative gas turbine not steam, which offers a smaller footprint. How you facilitate maintenance-work is also an important aspect, to access equipment and move it on and off the ship.
“From a maintenance point of view when you build a facility, its not just a design task, its how easy is it to run and maintain. That knowledge comes from our experience.”
Petronas has been in the LNG business since 1983 and is leveraging this experience for operations and maintenance of the new type of floating LNG plant. There are several levels of maintenance, including the remote gathering of data, especially for the rotating machinery. The main support team will be onshore, with a maximum crew of 150 on board FLNG Satu, consisting mainly of the operations team and first level of maintenance people. Any heavy duty maintenance will be from onshore, because offshore maintenance is costly and has to be planned. The number of people and supplies on the vessel also has to be carefully balanced with what can be called up by helicopter and supply boats.
The topside of FLNG Satu, including the turret, will be
completed first
Another of the major design decisions was which refrigerant to use. A variety of different permutations are available and were considered. Onshore a mix of propane is normally used, but the engineering team decided to use nitrogen for the FLNG. “We wanted to make it simple to operate. With nitrogen there is no need to import the refrigerant because it is taken from the air, which saves us a headache.” says Abidin.
“We hope that we have made the right decision in terms of the nitrogen cycle. One of its attributes is that you are dealing mainly in the gaseous phase. Being an offshore installation, dealing with gas is a lot easier than dealing with liquids, especially from a process point of view.”
Other influences on the design include the weather. There are some limitations around wave heights. Loading and unloading of LNG can only be performed up to a certain wave height. Another major influence is the gas field itself. The composition of natural gas and the contaminants it contains differ from field to field. FLNG Satu's process equipment has been tailored specifically for the Sarawak field, which it will operate in for 20 years, until the field is depleted. Moving costs money, towing to a new site and tethering the FLNG to the sea bed, for example, are costly operations. “Where it is economical to tie back from other fields it will be done that way. The motivation is never to move,” says Abidin. “You can't design for all sorts of gases. You have to have a boundary. If you go for a wide range, the facility has to cater for that. Putting all that equipment together on board costs money. It's a judgement call.”
The final barriers have been regulatory because FLNG Satu is the first ship with a LNG plant on top of it. Onshore plants are covered by codes and standards, but offshore is driven by marine class requirements and has to be class certified. There has therefore been a period where offshore regulatory bodies and Petronas have had to “acclimatise to each other's requirements”, Abidin says.
The difference between onshore and offshore is also reflected in the engineering team, says Wan Badrul Hisham, head of LNG projects for Petronas' upstream projects. He says: “In our management team there are people that have worked in plants and in LNG tankers. They have different ways of thinking. When you integrate them into the project you have to harmonise their thinking to get the technical specifications.”
Most of these barriers have been overcome now that the project is more than 80% complete. FLNG Satu is expected to begin operations at the start of next year and will be proof of Petronas' engineering expertise in the global LNG market. It will also demonstrate the company's position in the market. FLNG had been discussed as a concept for a long time, but it has taken a company that has control of the entire value chain, from exploration and production to distribution to consumers, to make it a reality. It's for this reason that FLNG's adoption may not be as widespread as many industry commentators have predicted. Hisham says: “There are very few people able to do this. We own the field and have the market. We can take the risk. If you are a new company and build a FLNG, they are capital intensive. You want to sell to an established buyer, but they will want security of supply and ask how reliable is the FLNG.”
However, both Hisham and Abidin believe there is a strong future for FLNG. Petronas has already assessed other opportunities around the world suitable for FLNG development. Abidin says: “There are plenty of opportunities. Our first focus is on our domestic field. Once the first is underway, hopefully over sites will be possible as well.
“Once the concept is proven to be succesful I think we will see a lot more.”