‘Sheen’ in water: Ageing oil pipeline off Gippsland coast shut off as leak probed

A pipeline linking two ageing ExxonMobil oil platforms off the Gippsland coast is being investigated as the source of a suspected hydrocarbon spill in Bass Strait.

The West Kingfish and Kingfish A platforms sit in more than 75 metres of water, about 70 kilometres off the Victorian coast from the internationally significant Ramsar-listed Gippsland Lakes.

Esso’s Kingfish A production rig in Bass Strait.Credit: Esso Australia Ltd

The pipeline, which sits on the sea floor, leaked suspected condensate – a low-density mix of hydrocarbons present in the extraction of natural gas – into the water.

ExxonMobil subsidiary Esso Australia Pty Ltd operates the Gippsland Basin Joint Venture – which supplies about 40 per cent of eastern Australia’s natural gas use – on behalf of a 50-50 joint venture with Woodside Energy.

A spokesman for the National Offshore Petroleum Safety and Environmental Management Authority said the agency had been notified by Esso on Saturday morning that a sheen was visible on the surface of the sea, southeast of the West Kingfish platform.

“The pipeline – which was reported to contain 95 per cent water at the time – has been isolated at both facility ends and is being depressurised,” the spokesman said.

“The facility has been offline for four weeks and continues to be so. An investigation has been launched and NOPSEMA is content Esso is currently managing the incident appropriately.

“As the investigation is ongoing it would not be appropriate to comment more at this stage.”

Esso is in the process of decommissioning more than a dozen oil and gas rigs in Bass Strait.

This masthead recently revealed Esso applied to the federal government for permission to “abandon in situ” eight decommissioned steel platforms – including Kingfish A – that have reached the end of their lifespans around Bass Strait in the Gippsland basin.

Louise Morris, oil and gas campaigner with the Australian Marine Conservation Society, said the leak was “part of a vast network of ageing and rusting offshore gas rigs in our oceans all overdue for decommissioning”.

“From the information available, this pipeline is in the early phases of decommissioning, and it’s deeply concerning that there is no clarity on how much oil condensate and decommissioning cleaning chemicals have been released into the ocean in this reported pipeline rupture,” she said.

“What we do know from Esso’s statement to the regulator is that there is a ‘sheen’ on the ocean surface which ... is now travelling through the ocean between Tasmania and Victoria through endangered blue whale habitat and countless other rare and threatened species, doing harm as it disperses into the ocean environment.”

The Kingfish oil field in Bass Strait was the first oil field discovered in Australia, in 1967.

A spokesman for ExxonMobil said the West Kingfish platform was “currently non-producing” and work was underway on Saturday to contain the leak.

“All work on the platform has been stood down and Esso is now using its aircraft to perform aerial observations of the sheen, and we expect the sheen will dissipate quickly,” he said.

“We are investigating the source of the sheen and, in an abundance of caution, we have commenced depressuring the West Kingfish to Kingfish A pipeline.

“Esso has notified all relevant authorities and will continue to provide updates as required. We will continue to investigate to identify the source of the sheen.”

The Gippsland Lakes wetlands are listed under the Ramsar Convention because of their importance to many endangered and threatened waterbird species.

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