If an oil spill happened in the Great Australian Bight, it could reach as far east as Port Macquarie's beaches, two thirds of the way up the New South Wales coast, according to a leaked draft environment plan obtained by the ABC.

Key points: Norwegian company Equinor wants to drill for oil in the Great Australian Bight

Norwegian company Equinor wants to drill for oil in the Great Australian Bight A leaked environmental plan shows an oil spill could reach as far east as NSW

A leaked environmental plan shows an oil spill could reach as far east as NSW Greenpeace and SA councils worried a spill could destroy fishing industry

Under a "worst credible case discharge" scenario, more than 10 grams of oil per square metre could wash up on some of Australia's coasts, according to the document authored by Norwegian oil company Equinor.

Maps show coastal areas that could potentially be impacted, from above Sydney to Albany in Western Australia.

Environmental group Greenpeace, which obtained the leaked draft Oil Pollution Emergency Plan, said it was the first time modelling had shown an oil spill could reach so far.

Greenpeace senior campaigner Nathaniel Pelle said the plan would be "utterly terrifying" for anyone who relied on the Great Australian Bight for their livelihoods.

"We've seen some modelling from potential accidents in the Bight before, what we've never seen… is the potential for oil to reach as far north along the NSW coast as Port Macquarie, including famous beaches like Bondi, like Manly, and like Newcastle," Mr Pelle said.

"The reason oil companies have to plan for worst-case scenarios is because sometimes they occur."

A map showing the maximum possible shoreline loading under 100 scenarios for an oil spill from a well in the Great Australian Bight. ( Supplied )

Equinor, formerly known as Statoil, wants to drill for oil off South Australia's Eyre Peninsula, with similar plans abandoned by BP and Chevron.

The leaked document shows the combined areas of risk under 100 different spills starting at various times over the October–May drilling season.

It shows how far the oil could travel in 60 days after the flow of oil is stopped by drilling a relief well to kill the original well.

In the plan, the drilling would take an estimated 102 days.

Situation 'extremely unlikely'

Equinor Australia country manager Jone Stangeland confirmed the document was part of an unfinished environment plan that had been distributed to state governments.

He said the map was "based on a extremely unlikely worst-case event, simulated 100 times in different weather conditions and without any response action taken".

Oil from the Great Australian Bight could reach famous Sydney beaches like Bondi. ( ABC News: Dean Faulkner )

In reality, the company would react swiftly, he said.

"The images don't represent an actual scenario, but the combination of 100 different extremely unlikely worst-case scenarios," he said.

"For Equinor, no oil spills are acceptable, and we will not go ahead until we are convinced we can drill safely."

He said the full draft environment plan would be released on the company's website and that of the National Offshore Petroleum Safety and Environmental Management Authority in the first quarter of next year for public comment.

"Equinor will be the first company to publish a draft environment plan for an offshore exploration well for public comment," Mr Stangeland said.

"We consider that transparency is essential in building trust with communities."

A map of potential oil exposure on the sea surface from a spill in the Great Australian Bight. ( Supplied )

He said Equinor had drilled more than 6,000 wells off Norway without any well incidents that resulted in pollution of the coastline.

It would only undertake drilling in Australia if it could be done safely, he said.

"We have extremely robust response arrangements so we can act immediately in the case of any unplanned event," he said.

A woman rescues a brown pelican in Louisiana after the Deepwater Horizon spill in 2010. ( US Coast Guard )

Debate over oil jobs versus effect on fishing

Since plans were first floated for oil drilling in the Bight in 2011, a fierce debate has been underway across the communities of the Eyre Peninsula that rely on the area's waters.

Whales in the Great Australian Bight in South Australia. ( ABC News: Nicola Gage )

According to a report commissioned by Australian Petroleum Production & Exploration Association, Equinor's plans to drill in the Bight could bring up to 1,500 jobs to South Australia over the next 40 years.

But members of the fishing industry see the plan as a direct threat to the industry that has provided for Port Lincoln since the 1960s and, according to the local chamber of commerce, account for 5,100 jobs in the city of 16,000 people.



Opponents point to the damage to the Gulf of Mexico caused by an explosion at BP's Deepwater Horizon rig.

After the accident, 750 million litres of oil poured into the Gulf's waters for 87 days.