The Australian federal government on Wednesday approved the Chevron, ExxonMobil and Shell’s environmental safeguarding at the Gorgon LNG Project on Barrow Island offshore northwest Australia.

The clearance process has taken four years to clear development for the country’s largest known gas formation, with estimated reserves of more than 40 trillion cubic feet of gas. A conditional okay had been given Gorgon in September by the State of Western Australia.

Gorgon is expected to produce for 60 years once plans become production.

As many as 30 sub-sea wells will be directionally drilled from a manifold in water 200 to 1,300 metres deep.

Gorgon is described as the “Snoehvit of the Southern Seas” for its sub-sea-to-beach concept, including the use of monoethylyne glycol and final liquefied natural gas plant as at Hammerfest in northern Norway.