ExxonMobil and its partner BHP Billiton have finally made up their minds over the way forward for their remote deepwater Scarborough gas field off the north-west coast of Australia, unveiling plans for a new world-class Floating Liquefied Natural Gas (FLNG) project.

The US major has been mulling (and often disagreeing) over various options with its 50/50 partner BHP Billiton for years, undertaking pre-Front End Engineering and Design (FEED) studies as far back as 2009 (see DI, 18 May 2009, page 1). It is now seeking Australian government approval to install what it says would be the world’s largest FLNG production facility on the field in the Carnarvon Basin.

The permanently-moored facility would process around 1.1 Bcf/day of gas, producing an estimated 6-7 MMt/year of LNG from five trains, it said in an application lodged with the Australian Department of Sustainability, Environment, Water, Population and Communities. The vessel would be 495 m (1,624 ft) long, larger than the FLNG facility under construction for Shell’s Prelude project in the Browse Basin.

Exxon says the Scarborough FLNG project is in the pre-FEED phase, and will progress to the full FEED stage later this year, with a Final Investment Decision possibly by 2014-2015. Up to 12 production wells would be drilled in two phases (seven between 2018-19 in Phase 1, and five more to follow in a later Phase 2). Offshore installation and commissioning of subsea infrastructure is estimated would take place in 2019-20. Approximately 125 km of infield flowlines and associated umbilicals will be installed, along with two manifolds. Between three and six flexible risers and umbilicals will connect flowlines to the FLNG vessel’s turret.

The vessel’s fabrication would almost certainly take place at one of the major SE Asian yards.

In 2009 the company awarded a pre-FEED to an alliance of JP Kenny, Mustang and Floatec for Scarborough, reviewing various floater options for the field, so a lot of the groundwork on this project has already presumably been covered.

Scarborough was discovered in 1979 and lies in 900 m (2,953 ft) of water, with estimated recoverable reserves of between 8-10 Tcf of lean gas. Any plans are also likely to include BHP’s Thebe gas field, around 31km away. It is approximately 220 km northwest of Exmouth in permit WA-1-R.