Scenarios before the latest conflict with Iran foresaw a quick price spike that fades if the attacks didn't affect oil shipping and infrastructure, such as Iranian pipelines and its Kharg island terminal.
However, there would be a bigger price spike and longer-lasting impact if oil infrastructure or supplies were interrupted because of the disruption of tanker traffic through the Strait of Hormuz.
Oil prices have already risen on war fears.
International benchmark Brent crude closed at a seven-month high of $US72.87 ($A102.56) on Friday.
Iran exports some 1.6 million barrels of oil a day, most of it going to China, where privately owned refineries are less concerned about the US sanctions that prevent Iran from selling its oil elsewhere.
If that supply is disrupted, Chinese customers would look elsewhere for oil on the global market, potentially driving up prices.
Another question is around the Strait of Hormuz, through which 20 per cent of global oil supply passes each day.
Middle East exporters Saudi Arabia, Iraq and the United Arab Emirates send most of their exports through the strait.
However, analysts say Iran has no incentive to try to close the strait because it would cut off its own exports and hurt its only big customer, China.
Limited strikes on Iran's nuclear program and the Revolutionary Guard that avoid regime change or all-out war could see prices jump $US5-$US10 ($A7-$A14) based on fear alone, according to Rystad Energy in a prewar scenario.
A wider war involving Iranian disruption of tanker traffic could see crude push past $US90 ($A127) per barrel and US gas prices "well above" $US3 ($A4.2) per gallon, according to another prewar scenario from Clayton Seigle at the Centre for Strategic and International Studies.
US petrol prices averaged $US2.98 ($A4.19) per gallon last week, according to the US motoring club AAA.
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