The National Offshore Petroleum Safety and Environmental Management Authority has deemed plans to drill the Stromlo-1 and Whinham-1 to be too complex, and asked BP to provide more detail on its plans, which involve drilling in a marine park.
NOPSEMA now expects to make a decision by October 28 at the earliest.
Earlier this month the regulator said it needed a further two weeks to consider BP's controversial plans.
The latest request for information is not an outright rejection or an invitation to resubmit the plan, so it does not put the project any closer to rejection or acceptance, a BP spokesperson told Energy News.
As it stands, BP is unlikely to mobilise the Ocean Greatwhite semi-submersible from Asia until it has approval to drill any well in Australia.
Given a transit time from South Korea, it means the earliest spud date BP can likely undertake is towards early December, if everything goes well, and with a planned 120-plus day drilling program the company's margin for error to complete the well before the autumn sets in, although EnergyNews understands the newly-built rig has been designed with the ability to drill all year round.
"The semi-submersible harsh environment rig selected by BP and its contractor, the Ocean GreatWhite, allows efficient drilling in the metocean conditions of the Bight through both summer and winter periods," the spokesperson said.
NOPSEMA has already rejected BP's environmental plans for drilling in the Great Australian Bight twice, finding they did not meet regulatory requirements.
In response BP carved out its plans for the first two of four initial exploration wells and crafted a new environmental plan in order to restart the clock.
NOPSEMA has been considering this latest application since August.
NOPSEMA has granted a request from BP for an extension to the timeframe for resubmission of the first environment plan, which now covers only the second two wells to December 31, 2016.
"The law requires all titleholders to thoroughly identify and evaluate the environmental impacts and risks that may arise from their activities and clearly demonstrate to NOPSEMA how those impacts and risks will be managed," NOPSEMA said.
It said the environment plan was being assessed by a dedicated environmental assessment team based on its technical and scientific merits.
The Wilderness Society, which has been leading the battle for the Bight, described NOPSEMA's refusals after almost a year of assessment and delays as a "farce".
"The risks posed by this project to the environment and the economy of coastal communities across southern Australia are simply too great," Wilderness Society South Australia director Peter Owen said.
"The time has come for this project to be terminated once and for all. One would expect BP to go to great lengths to show the regulator it had learnt from its Gulf of Mexico disaster and submit an application that far exceeds the required standards. Instead, it has again submitted a substandard application in the hope it will be approved."
Earlier this month BP released a summary of its oil spill modelling that shows a spill from an uncontained blowout from its proposed Stromlo-1 well could reach Adelaide in 20 days.
Drilling in the winter months could exacerbate the impact of any well blow out.
BP will accept the Ocean GreatWhite drilling rig from Diamond Offshore Drilling once it is satisfied that it has passed its rigorous testing, the spokesperson said.
Drilling will begin only once the onshore infrastructure is completed, and BP's contractors are ready to begin.
