Standing alongside Perth Catholic Archbishop Timothy Costelloe to open a new MercyCare building in West Perth yesterday, Barnett told media that negotiations with the joint venturers over the past couple of months had been "very productive", and that the supply chain "will be based out of Western Australia".

He said while the location of that supply chain was yet to be determined "obviously the Kimberley will play a major role".

"So [that means] a lot of jobs and supply of gas into the future," Barnett said.

"This project also is a major project in developing the Browse off the Kimberley coast - the partners [are not only] led by Woodside, but also include both Japanese and Chinese interest, so it will give a great deal of confidence throughout the economy.

"So despite the downturn in commodity trade and prices over the last 12 months or so, big projects still do get underway in Australia."

Asked when he expected the final investment decision to be made, Barnett said the joint venturers' decision to enter the front-end engineering design phase was "really a commitment to build the project.

"So all the technical design work will now be done, and I would expect a decision on FID to be probably a little over 12 months' time," Barnett said.

"The project is likely to be producing gas around 2021-22."

The JV confirmed in late May that James Price Point, which was already rejected as a plant location with the project becoming a proposed floating LNG development, would not be considered as potential supply base either.

Barnett's government had already bought more than 3000 hectares of land at the Kimberley coastal area from indigenous landowners by late 2013.

In March Barnett named "the location of a supply base in the Kimberley" as a key issue he had brought up with the Browse JV as one of two conditions for the government renewing the retention leases, along with securing domestic gas supply.

Woodside's announcement of the start of FEED for Browse followed the signing of a key principles agreement with the Browse FLNG proponents last week for the provision of domestic gas and a supply chain in WA - the first time the state's domestic gas policy will be applied to a FLNG project.

"I would like to thank the joint venture partners for the professional way they have embarked upon all the negotiations around this project," Barnett said yesterday in a statement.

"I am now looking forward to the development and finalisation of a detailed development agreement, prior to the joint venture making its final investment decision, which is expected in late 2016.

"This decision will lift confidence in resources and in the business community."

Under the key principles agreement the joint venture has committed to reserve gas equivalent to 15% of production from WA's share of the Torosa reservoir, one of three gas fields that make up the Browse project.

The integrated supply chain in WA will provide port, marine, aviation, storage and transport services over the life of the project.

Buried in Barnett's statement yesterday was also a note that WA's share of the Torosa field was estimated to be 65%, and that state royalties were estimated at more than $1 billion over the life of the project.

There had been hopes the royalties could be worth at least five times that much.

Asked in March about the federal government's belief that the changed boundaries resulting from the discovery in May last year on North Scott Reef would be worth at least $5 billion to WA over the life of the Browse project, assuming a $US50/barrel oil price, Barnett said: "It could be, and that depends on more detailed geophysical examination of the gas reserves and the production rate".

However, he cautioned that "we take a conservative view that over 20 years, royalties for Western Australia will be about $2.5 billion" - though he added that "they may well be above that".