The project involves the construction and installation of a 27,000 tonne floating Field Control Station (FCS), around 6500 tonnes of subsea compression infrastructure and 135km of submarine power cable linked to Barrow Island.
The station will be tied to the seabed by 12 mooring lines and will normally be unattended.
It is Chevron's most significant capital investment in Australia since the sanctioning of Gorgon Stage 2 in 2018.
Construction and installation activities are expected to take approximately five years to complete, with work to begin in the second half of 2022.
"Using world-leading subsea compression technology, J-IC is positioned to maintain gas supply from the Jansz-Io field to the three existing LNG trains and domestic gas plant on Barrow Island," Chevron Eurasia Pacific exploration and production president Nigel Hearne said. Hearne previously headed up Chevron Australia, later replaced by Al Williams.
"This will maintain an important source of clean-burning natural gas to customers that will enable energy transitions in countries across the Asia Pacific region."
Operator Chevron has a 47.3% interest in the project with ExxonMobil (25%), Shell (25%), and Osaka Gas, Tokyo Gas and JERA holding the rest.
Chevron Australia managing director Mark Hatfield said the project was expected to provide contract opportunities for Australian companies.
"We have developed a strong understanding of local capabilities from the Chevron-led Gorgon and Wheatstone projects and have leveraged this knowledge to shape work scopes aligned to local expertise," he said.
The announcement was cheered on by Australia's chief oil and gas body, APPEA.
"For the approximately $6 billion FID to be reached shows the confidence in our industry, the hundreds of thousands of jobs we support both directly and indirectly and how we have a large role to play in a cleaner energy future," APPEA chief Andrew McConville said.
"The announcement guarantees long-term, reliable operations, ensuring Gorgon continues to deliver vital natural gas supplies to customers in Western Australia and Asia for decades to come."
Chevron has just finished dealing with a slew of technical issues at Gorgon, after cracks were found in one of the Train's kettles, leading to a staged shut down of all of the facilities three train's over a period of 6 months.