The company also launched a video of the project's riser support structure installation yesterday.

Inpex general manager Vince Kenny said lifting the roof, which spans 90m and weighs 1100 tonnes, to its final height of 32m took just over five hours to complete and required only 0.3psi of air pressure, having been constructed on the tank floor and raised using two powerful fans.

Ichthys will use the same process to raise the roofs of two remaining cryogenic tanks at Bladin Point, comprising one propane tank and one butane tank.

Inpex said over 80 people were involved in the lift, including a team of 30 welders who scaled the tank to fix the roof to the outer walls.

Each of Ichthys' two LNG storage tanks will have a volume of 165,000 cubic metres and will stand 46m high and span 91m.

When operational, Ichthys will need three LNG carriers and one LPG carrier to export product from Darwin Harbour each week, plus one or two condensate carriers per month.

The project started drilling at the Ichthys gas-condensate field about 200km off Western Australia's coast in February, with the first well spudded on February 3 using development drilling rig ENSCO-5006.

The video launched yesterday shows the November 5, 2014 event when deep water construction vessel Aegir installed the Ichthys LNG project's 6500t riser support structure (RSS) tower in the Ichthys field.

Soon after, the RSS arch was installed, measuring in at 120m long and 20m wide.

The RSS now stands firm with its arch reaching about 110m off the seabed.

It will hold up a network of rigid and flexible flow lines and umbilicals that run between the Field's five drill centres and the central processing facility (CPF).

More than 180km of subsea flow lines will connect the drill centres to the CPF and the CPF to the floating production, storage and offloading facility, which will be moored about 3km away.