This week gas began flowing into the $1 billion fourth train where it will be liquefied for export from the Burrup Peninsula in Western Australia.

Woodside Energy, operator of the Venture, has begun commissioning the train in readiness for meeting expanded production commitments this year.

First gas has flowed into the acid gas removal system – the first phase of the multi-stage liquefaction process – and is now entering the LNG train as part of commissioning.

The construction phase is all but finished with insulation of pipe and vessels

being the major work still ongoing, while commissioning is nearly 90% complete.

Woodside's chief executive officer of the North West Shelf Venture, Steve Ollerearnshaw, said the new train was being brought into operation in stages, with many areas already commissioned and operational, including the acid gas removal unit, power generation facilities, and process utilities such as nitrogen, air and water.

The new train will boost LNG production capacity at the venture's onshore gas plant from 7.5 million tonnes a year to 11.7 million tonnes making it the biggest single LNG train in the world and the biggest construction project in Australian since the original North West Shelf LNG developments in 1980s and 1990s.

"The introduction of first gas into the front-end of the train achieves another major milestone in the expansion of the venture's LNG facilities,” Ollerearnshaw said.

In February 2004, gas began flowing to shore through the venture's new second offshore trunkline and this was followed in April by the arrival and loading of the venture's ninth LNG carrier, Northwest Swan.

Mr Ollerearnshaw said the total estimated expansion project cost, including the ninth LNG carrier, remained at $2.7 billion.

"This latest milestone concludes three years of hard work at the site where the work force, which peaked at more than 2400 people, set new benchmarks for safety on a heavy construction site,” he said.

Mr Ollerearnshaw said that the expansion project has yielded a larger, more efficient and reliable operating system, thereby providing a strong platform for further growth of the Venture’s gas business both in Western Australia and overseas.

“This culminated in late June with the dual operation of the Venture’s two offshore trunklines and the completion of related pipeline modifications under the North Rankin A production platform.”

The six equal participants in the North West Shelf Venture are BHP Billiton Petroleum (North West Shelf); BP Developments Australia; ChevronTexaco Australia; Japan Australia LNG (MIMI); Shell Development (Australia) Proprietary and Woodside Energy (operator).