New plans for oil in the Great Australian Bight have been released.

Norwegian company Equinor has released an environment plan on Bight drilling, which discusses a range of measures to be taken in the event of a disaster.

It comes after an internal draft emergency plan prepared by Equinor was leaked, causing concern due to the “worst credible case” scenarios it modelled.

Equinor wants to drill at a depth of almost 2.5 kilometres by the end of 2020, but is waiting on approval from the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA).

“The [environment plan] details what Equinor will do in the very unlikely event that anything goes wrong,” Equinor Australia manager Jone Stangeland said.

“This includes a plan about how we would work with the southern states to protect the coastline.”

The company says it can do the drilling safely, and could bring “a big opportunity for South Australia” if it was approved.

“Equinor has implemented strict barriers to prevent a spill, [prepared] intervention and mitigation measures as backup and is confident that the risk has been reduced,” the report states.

“Lessons learned from major incidents in the last decade, in particular the Deepwater Horizon [incident] in 2010, have resulted in the advancement of regulations.”

Environmental activist group Greenpeace says the official version of the report still shows there are enormous risks.

The new report includes the option of using a piece of machinery called a “capping stack” to plug a major leak, but the company admits it would take 15 days to be transported from Singapore.

That would mean oil flows freely into the ocean for 15 days in the event of a major leak.

“This report whitewashes over the danger,” senior Greenpeace campaigner Nathaniel Pelle said.

“To kill the well, to stop it permanently — which took BP 149 days in the Gulf of Mexico — Equinor are guessing they could do it in 102 but there's really nothing in here to justify why they make that argument.

“There's no plan for how they're going to clean up an accident if it occurs.”

The report predicted the potential costs to human and marine life in the event of an “unplanned loss of well control”.

“Commercial fisheries and aquaculture may be affected by temporary fishery closures, restrictions on sales … or effects to market value,” the report said.

The socio-economic impact of a spill “would vary … but have potential for long-term effects to the region and state economies”.

“Some fish species of commercial value, specifically the southern bluefin tuna are seasonally present in the area largely in the first quarter of the year … [and] could be potentially exposed to elevated hydrocarbon concentrations in the water column,” the report said.

“The effect of a 102-day release of oil on Australian sea lions could have a very long or permanent impact on a population that is already in decline.”

The draft environment plan has been put to public consultation for 30 days, and is accessible here.