The greenfield development in the Carnarvon Basin saw the Australian operator take it from initial discovery in 2005 to first LNG production in just seven years, a major achievement for a world-class project.
According to Feisal Ahmed, Executive Vice President, Technology at Woodside, Australia’s first deepwater gas development features some significant firsts, including the longest gas well subsea tieback (210 km) to the onshore LNG plant on the Burrup Peninsula, as well as being the first LNG project to use pre-fabricated mega modules. It also saw the operator use only five big bore wells to feed the gas plant.
The main source of the dry gas is the 5 Tcf Pluto field, with further reserves to come from the nearby Xena field, discovered in 2006 and which will be tied into the subsea infrastructure at a future point.
“We are currently going through a Basis of Design process at present on that,” he said. Both fields lie in water depths of around 800-1,000 m (2,625-3,281 ft), with the gas tied back to a 15,000 tonne fixed jacket riser platform sitting in 85 m (279 ft) of water.
Ahmed highlighted the current crop of major LNG projects underway in Western Australia, with seven having had a Final Investment Decision for about 13 LNG trains. Other nearby LNG projects include the North West Shelf hub, the Wheatstone hub, the Gorgon hub and the recently confirmed ultra-deepwater Scarborough LNG project. “But Pluto was the first,” he said. The company recently shipped its 50th cargo of LNG, having delivered the first one mid-2012.
The company’s use of big bore wells was a novel approach, although Ahmed says that the company only uses three to feed the plant, with the other two essentially acting as spares. The big bore wells in around 850 m (2,789 ft) of water enable the company to achieve flow rates of up to 400 MMcf/d per well, which feed the 4.3 MM tonnes per annum onshore LNG train via a 36-inch pipeline.
Much of the project’s success in terms of scheduling came down to Woodside’s attention to detail, especially with regards to the pace of both the onshore and offshore work: “We really put a lot of effort into the co-ordination of the offshore and onshore pace so that we really would get startup on schedule,” said Ahmed.
Woodside was also able to use its experience from its other LNG projects, such as its Angel project, where it also employed big bore wells to essentially get more gas from fewer wells. It also decided to use 7-inch expandable sand screens in the wells.
Looking ahead beyond Pluto, Ahmed went on to flag up the company’s interest in both subsea processing and floating LNG solutions for future projects. “Subsea processing is the future, in many ways, and that’s what we will be pursuing. How much further beyond 200 km can we go? Can we go 300 km, even 400 km, and basically eliminate platform structures?” he commented.
He also highlighted the company’s recent decision to change its plans for the Browse LNG project, also offshore Western Australia, which saw it ditch plans for an onshore LNG plant and go back to the drawing board to consider other potential solutions, including a floating LNG option. “This project is 400 km offshore, and when it got to the costs we got to an end point where it was not feasible to proceed with that plan, which had three floating dry tree platforms. We are now going to recycle that, and look at other technologies.”
The company also has its 5 Tcf Sunrise LNG project in the Timor Sea currently under discussion. Woodside wants to use Shell’s FLNG technology for the project, like it is considering for Browse, and is hoping for a resolution to move it forward.
It also has its recent agreement reached with Noble Energy and that company’s partners to enter the Leviathan project offshore Israel in the eastern Mediterranean Sea, which is also set for eventual phased development including an FLNG solution.
Woodside operates Pluto with a 90% interest, with its partners being Tokyo Gas (5%) and Kansai Electric (5%).
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