Origin also disputed rumours that the vessel, which was to provide accommodation for workers undertaking rectification and maintenance works on the Yolla A Platform, had departed Melbourne to return to Singapore for repairs.

“Origin can confirm that suggestions the vessel has left Melbourne and that the owners of the Safe Concordia have decided to abandon their contract with the BassGas Joint Venture are not correct,” said investor relations manager Dr Angus Guthrie.

“Based on advice from the owners of the Safe Concordia, Origin had previously advised the market that repairs were likely to take up to six weeks and that the vessel was likely to return to the BassGas site in early-November.”

He said Origin was waiting on further advice from the vessel’s owners about the preferred alternative and timing of repairs. The market would be advised once this was determined, he said.

On September 21, Origin announced serious problems with the vessel, which it said could take six weeks to fix. Shortly before arriving in the Otway Basin on September 12, one of the vessel's four thrusters malfunctioned. While the joint venture scrambled to assess whether it was safe to operate with only three thrusters, a second one blew six days later on September 18.

At the time, Origin said the vessel had gone to Port Phillip Bay for repairs – the cost and execution of which was the owners’ responsibility, said Origin.

Delays to the schedule and initial production from the BassGas project were likely, said the company.

BassGas is a partnership between Origin Energy as operator (42.5%), AWE (30%), CalEnergy (15%) and Mitsui subsidiary Wandoo Petroleum (12.5%)