The company said it had drilled 80 wells as well as built and commissioned its facilities at Roma North and Atlas that will be able to deliver 20 petajoules of gas a year.
Managing director Ian Davies said the project was executed superbly and delivered in two years.
He said the company would be delivering gas to the domestic market for decades to come.
Separately, the Mahalo gas project, inland from Gladstone has been granted environmental approval.
The project is held by Comet Ridge, Santos and the Origin-led APLNG.
The project is now waiting for a petroleum lease from the State Government.
Comet Ridge managing director Tor McCaul said considerable environmental work had been done before the approval was granted and this would benefit the Mahalo North project.
He said the environmental field work for Mahalo North would start last this year.