The protests surrounded the state government passing legislation to extend the life of the North West Shelf project by another 25 years from 2034 to 2059 so Woodside may send gas from its planned Browse gas field development to the processing facility it operates and shares with other equal joint venture partners.
The passage of the Bill comes months after it was expected, after the legislation became stuck in the parliament while the Liberal opposition filibustered a separate bill to legalise voluntary assisted euthanasia late last year.
Once the Bill becomes law it will allow Woodside to make a final investment decision for the Scarborough field development, something the McGowan government has pushed for over the last 12 months.
It will also allow for a third party toll gas at the Karratha gas plant.
The protest was organised with the help of the Conservation Council of Western Australia, whose report on the planned development suggests it will be four times more polluting than Adani's Carmichael coal mine in Australia and equivalent to 35 coal-fired power stations.
Woodside's Burrup Hub plans comprise an expanded Pluto LNG plant fed by the Scarborough gas fields, an internconnector pipe between it and the North West Shelf LNG facility and development of the Browse gas fields to backfill the five-train NWS.
It says over the lifetime of the project it will emit 6 billion tonnes of CO2.
The protest saw a better turnout than some others this year - Energy News counted only four clad in black robes on St George's Terrace some weeks ago - though the number remained dwarfed by other climate strikes in the eastern states.
Dozens of people protested the development, using drums and other noisemakers in order to raise a racket over emissions when politicians remained quiet.
Both the ruling Labor party and the Liberal-Nationals are in favour of the development.
Extinction Rebellion spokesman Jesse Noakes couldn't tell Energy News what size coal-fired station you would need for 35 of them to equate to the lifetime emissions of the planned LNG development but was adamant Woodside and partners were now in protesters' sights.
"Social license is what we're coming for," he said.
"We're going to erode and efface their social license the way they're eroding and effacing the Murujuga rock art on the Burrup Penninsula."
That art, some of the oldest in the world, could be threatened by further development of the area, according to CCWA, and it has been one of the lynchpin arguments outside of emissions it has used to argue against Woodside's plans believing it could bring other protestors to the table who might be not as concerned about climate change.
"This is a fully stacked campaign," Noakes said.
Noting the low oil price and possible effects on the sanction and development of new projects should Brent not rally he did concede, "the Saudis might do it for us" but plans to continue protests and a two week vigil in the part opposite Parliament just in case.