A Norwegian oil company granted environmental approval to drill in some of Australia's roughest seas has worked to ease fears about any oil leaks as it continues to clean up a spill about 17,000 kilometres away in the Bahamas.

Key points: Equinor says an oil spill in the Great Australian Bite as a result of drilling was "highly unlikely"

Equinor says an oil spill in the Great Australian Bite as a result of drilling was "highly unlikely" They promise to get a capping stack on location within 15 days in the event of a well blowout

They promise to get a capping stack on location within 15 days in the event of a well blowout A clean-up of an onshore oil spill on Grand Bahama Island is currently underway

A Federal authority yesterday accepted Equinor's environmental plan for an exploration well in the Great Australian Bight off the coast of South Australia, leaving it one step closer to drill in waters nearly 2.5 kilometres deep.

The National Offshore Petroleum Safety and Environmental Management Authority made the decision despite widespread fears about the difficulties of containing any oil spill in a remote region where seas typically reach six to seven metres.

Equinor Country Manager for Australia Jone Stangeland said the company had reduced the amount of time it would take to get a capping stack to the location — 400 kilometres south-east of Ceduna — in the "very unlikely event we have an oil spill".

"It [previously would have] taken 30 to 40 days to get it from storage to location," he told ABC Radio Adelaide.

"We have worked very hard to reduce this time and now we can get it from where it's stored within 15 days."

Equinor cleaning up oil spill in the Bahamas

Equinor is currently working to clean up an onshore oil spill at Grand Bahama Island after a storage facility was damaged by Hurricane Dorian in September.

But Mr Stangeland pointed out that the "tragic event" was not related to any exploration work.

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He added that an ocean soil spill that took place in 2007 off the Norwegian continental shelf, when the majority state-owned company was called Statoil, was not related to exploration activities either.

"It was related to the offshore loading of oil in the field," Mr Stangeland said.

Equinor argues on its website that there have been 13 exploration wells drilled in the Great Australian Bight over the past 40 years.

Its own modelling shows that a worse-case scenario oil spill in the Bight would see oil stretching as far west as Albany in Western Australia, to Port Macquarie in New South Wales, while the coastlines of South Australia and Tasmania would be completely encompassed.

This scenario, however, assumed that every piece of safety equipment on a rig failed, and that nothing was done to contain or disperse a leak from an open hole for 100 days.

Mr Stangeland said the company, which wanted to start drilling in November next year, had also provided "financial assurance" for any oil spill clean-up as part of its environmental plan.

"We have also provided a financial scheme if there are any spills related to our activity, to make sure that all people can be compensated in a fair and good way immediately after any spill should occur," he said.

Accident response questioned

Greenpeace head of campaigns Jamie Hanson said an oil spill could never be truly cleaned up.

"Once it's in the environment it will be coating the beaches, making animals sick and destroying the seafood industry," he said.

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"And in an uncontrolled oil spill, they might get a capping stack there in 15 days, but who knows how long it will take them to get it on the sea floor.

"We saw what happened in America with the Deepwater Horizon accident."

That spill, which took place in the Gulf of Mexico during 2010, took BP some 87 days to plug after a well blew 1.6 kilometres below the surface.

Production still years away

Equinor must still get approval for a well operations management plan and a facility safety case before it can undertake any activity.

If it passes these final two hurdles, it will drill for about 60 days from a mobile offshore drilling unit.

Once the well has been drilled it will be permanently plugged and abandoned.

Federal Resources Minister Matt Canavan argues that drilling would help provide fuel security. ( ABC News: Lily Nothling )

Federal Minister for Resources and Northern Australia Matt Canavan stressed that the application was only for an exploration well and any production phase was a number of years away.

"If this goes to production one day, there is a separate process where Equinor or others need to apply for a production licence," he said.

He said an economic report last year found that about 1,500 jobs could be created if the production went ahead, with a support base to be built at Ceduna.

Mr Canavan argued that drilling in the Bight was necessary because oil drilling in Bass Straight was in decline and the "oil-producing province" needed to be replaced to support manufacturing jobs in southern Australia.

He said domestic oil production in the 1970s enabled Australia to be "relatively fuel sufficient" during the oil crisis of the 1970s.

The number of oil refineries operating in Australia has since declined from 10 locations one decade ago, to just four.