That could flood an already saturated market with oil, as Iran holds around 10% of the world's known reserves, number four globally after Venezuela, Saudi Arabia and Canada and ahead of Iraq, which is restoring its oil industry in Kurdistan.
Iran also has almost a fifth of gas reserves, second only to Russia, but much of those reserves have never been developed, and those who have tried, such as Liquefied Natural Gas Ltd have reported that it was all too hard.
If the Western powers and the Middle Eastern nation can come to an accommodation over Iran's nuclear sector - and that could happen as early as this weekend, although that seems unlikely - Iran could start the process of wooing new investment into the sleeping giant that is its oil industry.
Iran's oil minister Bijan Namdar Zangeneh recently said that the country could easily increase production by one million barrels per day within months of sanctions being lifted, which given there is already a 2MMbopd glut, and more to come from expansions already underway, would place a tremendous downward pressure on the commodity's pricing.
Oil has already been pushed down to $US50/bbl since last year, and some analysts predict that if the talks between Tehran and the West in the Swiss city of Lausanne go well that could trigger a further sell down towards $US20/bbl.
At that level, it could almost certainly kill off some of Australia's few, high cost oil producers.
In 2011 Iran was producing around 2.5MMbopd, while in 1978 it peaked production at 6MMbopd, depending on which reports you read.
There's some discussion over how much Iran can produce now, and how quickly, but there is between 7-35MMbbl already in storage and ready for sale.
It has been restricted to 1MMbopd since the sanctions were imposed.
Iran would need to attract the likes of Eni, BP, Shell and Total back into its arms, and negotiate the Organisation of Petroleum Exporting Countries quota system - or break away from the 12 member group and go it alone.
That move would make little economic sense in a $US20 per barrel world, as Its large fields, including Gachsaran and Marun, have been in production for more than 50 years and will need some considerable investment, for which the returns may just never been there.
Iran may need between $US50-$US100 billion in investment from foreign oil groups to boost its output, at a time when international oilers are scaling back their budgets, however the mix of risk and reward will almost certainly find some willing participants.
Also in the background is Iraq, which has around 150 billion barrels of proved reserves and more than 300 billion barrels of unproved reserves, which makes Iraq the second largest oil country in the world after Saudi Arabia.
Investment sentiment to Iraq is cool given the nation's internal issues, but there is plenty of interest in Kurdistan, which says it has about the eighth largest hydrocarbon reserves in the world, with Kurdistan alone has 50Bbbl of proved reserves and 80Bbbl of unproved reserves, in addition to 8-10 trillion cubic metres of natural gas reserves.
The talk of Iran's return to the global community, and more Kurdish oil developments, are contributing factors putting further downward pressure on the oil price. Benchmark Brent oil settled down 12c to $US56.29 a barrel [$73.52/bbl] overnight, while US crude finished down 19 cents at $48.68/bbl [$A63.59/bbl].
Both tested lows about $US1.20 per barrel below those levels during trading overnight.
In Australian dollar terms, Australia seems to remain viable, at least for companies in the Cooper Basin.
Drillsearch and others are producing oil at around $45 per barrel, with cash costs are about $25/bbl and depreciation and amortisation charges at $20/bbl.
It's still viable at the current price of $55-60/bbl for Tapis crude, but the lifting costs for oil in the Cooper/Eromanga Basin are reported to be one of the most competitive in the world.
But in a world of $US20/barrel there will be few winners, because there are few Australian companies that can produce profitably at $A26/bbl.
