In a country where mega resources projects roll around as regularly as grand finals, there is one project which exhausts more superlatives than any other.
That project is the North West Shelf oil and gas operation off Karratha, and its $5 billion expansion of recent years, which has set a new benchmark in Australian engineering excellence.
Back in the 1980s, the North West Shelf was the largest engineering project in the world, and to this day, it remains Australia’s largest resources development project.
Not only does this industrial behemoth dwarf many of its international competitors in size, but construction of the North Rankin Redevelopment Project between 2008 to 2013 utilised some radical engineering solutions.
These included using the world’s biggest barge to carry a 274m high platform, which was the tallest ever installed in open water.
The float-over method was used to steer the barge between the jacket legs, gently lowering the topsides in place.
The topsides weighed 24,250 tonnes, making it the second heaviest float-over installed in open water. The topsides were placed on to a four-leg jacket which is connected to the seabed by 16 piles.
To top off the impressive feat, the second platform was built at the same time that contractors extended the life of the existing platform.
And at all times during the four-and-a-half-year construction, the North West Shelf managed to deliver gas at capacity. Failure to do so would have hurt the State’s economy.
Woodside Energy, WorleyParsons, KBR, Honeywell, I&E Systems and Transfield Worley were recognised by Engineers Australia last year, taking out the top prize in WA for engineering excellence.
The impact of the facility cannot be underestimated.
By extending the life and the reach of the facility, allowing it to extract remaining low pressure gas from the ageing North Rankin and Perseus gas fields, it has extended gas supply by many years.
A submission from Woodside to the EA awards noted that the float-over was one of the most unique aspects of the projects, claiming it is now being copied on other projects.
“The float-over operation required significant re-engineering of the world’s largest barge, which included removing one-third of its width along 40 per cent of its length to enable the topsides to be transported and installed on to the jacket,” said the submission.
“It was imperative that the barge carrying the 24,250-tonne topside through seas of up to 17m high did not fail catastrophically.
“The successful float-over was a pioneering feat which others are now following.”
Written by: Kim Macdonald
Originally published in the Australian Engineering Week liftout in The West Australian on 3 August 2015.