A Deloitte report commissioned by Woodside on its proposed drilling at Browse Basin off Western Australia claims the project will deliver $147 billion in uplift to the state over its lifetime.
It also says the state will fail to achieve net-zero emissions by 2050 on its current trajectory.
The project, which is undergoing environmental assessments, would support the nation's energy transition to renewable sources, the report says.
However, with or without the project, it says renewable and energy storage would need to be deployed at rates far above what has occurred in the past for WA to reach the 2050 target.
Australia is bound by legislation to reach net zero by 2050, with the WA government recently saying the state was committed to the goal.
The project, slated to start production in 2030 and run for up to 44 years, would deliver more than $56 billion in taxes, royalties and excise, the report says.
Environmental groups were scathing of the report, with some saying it failed to paint the full picture of potential impacts.
The report notes the project's potential impacts on domestic gas prices, contributions to decarbonisation outcomes in Asia and broader environmental considerations were outside its scope.
"This report should be read alongside complementary studies that examine these issues in greater depth to provide a more complete understanding of the project's implications," it reads.
Australian Conservation Foundation chief executive Adam Bandt said people and nature would pay the price if the development proceeded.
"Exported coal and gas comes back to Australia as heatwaves, bushfires, floods and coral bleaching," he said.
A report by the Institute for Energy Economics and Finance found Browse gas would likely be four times more expensive than existing domestic gas.
The Browse fields were also "carbon dioxide-intensive", with an average concentration higher than many other gas fields.
According to the most recent data, WA was behind Queensland and NSW for emissions in 2022/23.
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