Australia's deepest offshore drilling operation has won approval from regulators before its environment plan has been made public under disclosure rules that have since been tightened.
Esso this week won approval from the National Offshore Petroleum Safety and Environmental Management Authority for plans to drill for gas about 100 kilometres off the Victorian coast in Bass Strait in its Sculpin prospect.
The company, owned by US energy giant Exxon, expects to drill as deep as about 2300 metres, or slightly deeper than the 2240-metre oil well proposed by Norway's Equinor in the Great Australian Bight, the agency said.
New rules to increase transparency of environmental plans for offshore drilling came into effect on April 25 - but don't apply to either Exxon or Equinor as their proposals were lodged earlier, an agency spokesman said.
The new rules require draft environment plans submitted to the agency to be published before regulatory assessment, with a 30-day public comment period to apply to environment plans for seismic surveys and exploratory drilling.
Madeline Taylor, a natural resources law expert at the University of Sydney, noted Equinor had voluntarily released its environmental plans for scrutiny, and called on Esso to follow suit, given the similar scale and complexity of the drilling.
"Clearly Equinor is adhering to best industry practice in an effort to uphold transparency and accountability to the community," Dr Taylor said. "Both of these aspects are critical to attaining a social licence and applying best practice standards."
Esso, Resources Minister Matt Canavan and the Victorian government were approached for comment.
Environmental groups have opposed Equinor's plans, noting the company's own oil pollution emergency plan identified risks from a well blowout included fouling beaches from Albany in Western Australia to as far as Sydney's beaches.
Dr Taylor noted both companies' wells would be among the deepest globally. The maximum depth of North Sea wells, for instance, was 725 metres, while the world's deepest subsea well is in the Gulf of Mexico at 2700 metres.
BP's notorious Deepwater Horizon blowout in 2010 was drilled to waters about 1500 metres deep, and leaked about 4.9 million barrels of oil over five months until the well was sealed.
"Deepwater offshore drilling is extremely risky," Jamie Hanson, Greenpeace Australia's head of campaigns, said. "As we saw with the Deepwater Horizon disaster, it simply isn't possible to eliminate the real risk of catastrophic accidents."
Mr Hanson said that, given the climate emergency, new fossil fuel developments should cease.
The announcement of Esso's approval comes as a class action trial over a 2009 oil spill in the Timor Sea led by Maurice Blackburn Lawyers went to trail in the Federal Court on Monday.
The law firm is acting on behalf of 15,000 Indonesian seaweed farmers against the oil company PTTEP Australasia over oil and gas leakage from its Montara rig located about 690 kilometres west of Darwin.
- SMH/The Age