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gets underway in earnest. Shell has decided to push the go button on the project as it believes that FLNG will enable the development of gas resources, ranging from clusters of smaller more remote fields to potentially larger assets via multiple FLNG facilities where an onshore development is not viable. Prelude was discovered in 2007 by Shell in the WA-371-P permit, an area which covers around 1,000 sq km in the remote Browse Basin, 475km north-northeast of Broome, Western Australia. Marjan van Loon, Shell vice president for LNG projects and technology, said at a briefing at the company’s technology centre in Rijswijk, the Netherlands: “If you have a discovery a long way from your customer then the normal option of putting the gas in a pipeline might not be possible for economic reasons. “FLNG has become a hot topic in the past year or two, but it is not that recent. At Shell we have been busy on it for nearly 15 years already, starting with studies, simulations, testing and development work. “We’re not building this because it is such a large complex facility and because as engineers we’re very excited about it. We’re doing it because it makes business sense. FLNG really monetises gas that could not otherwise be monetised economically.”
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SHELL IS set to become a gas company this year as it produces more gas proportionally In Brief than oil for the first time. Matthias Bischel, projects and technology director at Shell, said: “By the end of the year our gas production will account for 51-52% of our overall production. We are becoming a gas company and there are several elements to that. “On one hand it is LNG, in which we have a very long history going back to 1964 in Algeria. Since then we have been producing LNG in a whole range of countries. “Unconventional gas is also something we are involved in. We have a significant acreage position in the US and Canada, and in China we have several joint ventures with PetroChina where we are in the exploration phase for gas.” Meanwhile, Inpex says it has agreed a deal to take a 17.5% stake in Prelude from Shell.
She said energy demand is expected to double or triple over the next few decades as emerging economies develop. “We need all the energy we can get our hands on. We need renewables, we need oil, we need gas. Gas is important because it is the cleanest fossil fuel.” According to the US Energy Information Administration, there is more than 250 years of gas available in the world at current consumption rates. There is estimated to be 4050 Tcf of stranded gas offshore Norway, 60-70 Tcf off East Africa, 30-40 Tcf off Brazil, 3040 Tcf in the Asia pacific region and 100-110 Tcf offshore Australia, which could be tapped through the FLNG concept.
Offshore Technology April 2012
“These are remote resources that normally could not be piped to an onshore plant that you can now make economic. There are several reasons for it. You can put the floater close to the field and you can also use the floater to tieback several smaller fields. “You can have a big field and put several floaters on it, so you can play with the floater and the concept. The floater is also re-deployable, so you don’t need one field with 20-30 years of gas reserves to underpin one floater. It brings flexibility and is comparable in cost to onshore LNG or cheaper. How Prelude FLNG compares to world’s tallest structures
“FLNG is still a very small player in the LNG space. We believe it is complementary because it is aimed at these remote fields.”
FLNG – a complex solution Harry van de Velde, principal process engineer FLNG with Shell, explained at the technology briefing that the FLNG concept is far more complex than just transferring onshore plant to an offshore environment. “One of the key things for offshore FLNG is that you will have tanks that are not completely filled, and with the ship slightly moving you are at risk the LNG will slosh, so you need to be able to predict what forces this will exert on the tank. “We did a lot of work on this and we have models that can predict this. The other key thing you need to sort out is how you offload the LNG to an LNG carrier. On Prelude the FLNG vessels will moor alongside the FLNG vessel and will be connected by means of offloading arms. “They use the same principle we use for offloading at onshore plants, but they are doctored for the offshore environment. There has been a lot of work done to design the offloading arm for both LNG and LPG. A lot of simulations were done to simulate how a carrier could moor alongside the FLNG.” He said another key compo-
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