Woodside Petroleum (WPL) has started up its $5 billion North Rankin redevelopment project and exported its first gas to the Karratha gas plant.
Woodside chief executive Peter Coleman said the start-up had been achieved as planned and on budget.
"Start-up is a major milestone given the complexities of integrating a new 65,000 tonne facility next to an existing offshore production platform," Mr Coleman said.
He said the redevelopment extended the North West Shelf's resource life and supported the project's onshore gas commitments.
Woodside holds a 16.67% share in the North Rankin redevelopment project which is 135km offshore from Karratha.
The redevelopment has involved the construction and installation of a second platform, North Rankin B, and modification and refurbishment of the existing North Rankin A platform.
Woodside holds an equal stake in the North Rankin redevelopment with BHP Billiton (BHP), BP, Chevron, Japan Australia LNG (MIMI) and Shell.
Woodside shares were 28 cents lower at $37.62 at 1223 AEDT.