Norwegian energy giant Equinor says the Bight "could be one of Australia's largest untapped oil reserves" and wants to drill a well more than 370 kilometres off the coast of South Australia.

Drilling of the proposed Stromlo-1 well will begin in the summer of 2020/21 if it receives all necessary regulatory approval.

Beach protests have been held around the country condemning the project, including in the NSW south coast seat of Gilmore where the Labor leader campaigned on Wednesday.

"If I form a government, one of my first decisions will be to get an oil spill study," Mr Shorten said.

"I want to understand the consequences of an oil spill in the Bight ... and I think that that is what is concerning a lot of our surfers and people who care about our coastline."

Equinor has submitted an environmental draft plan to the regulator for offshore petroleum safety.

South Australian Labor senator Penny Wong said it was a sensible approach to conduct a study, working alongside the regulator.

Liberal senator Simon Birmingham, who also hails from SA, said it was change of position for Labor.

"Yesterday Labor still backed the national independent offshore exploration agency to do the full analysis and back it," he told a debate in Adelaide.

"This is just trying to play into a little bit of local populism."

Greens senator Sarah Hanson-Young said the modelling was already available and showed any spill would not only ruin South Australia's coastline but spread along the Victorian and NSW coasts.

"It would be devastating. So I guess the question that does really need to be answered is will a Labor government commit to stopping oil drilling in the Bight after they've done this review, after they see the results for themselves and make sure South Australia doesn't have to bear it."

Australian Associated Press