Global benchmark Brent crude futures were up 39 cents at $74.39 a barrel at 11:36 a.m. EDT (1536 GMT), while US West Texas Intermediate (WTI) crude slipped 13 cents to $67.92 a barrel.
"The turnaround from yesterday seems to be the re-pricing of geopolitical risk, especially of the United States potentially pulling out from the Iranian nuclear agreement," said Gene McGillian, manager of market research at Tradition Energy in Stamford, Connecticut.
A top adviser to Iran's supreme leader said Tehran would not accept any change to its nuclear deal, as Western signatories prepare a new package in the hope of persuading US President Donald Trump to stick with the accord.
"If Trump exits the deal, Iran will surely pull out of it," said the official.
This comes a day after French President Emmanuel Macron said he expected Trump to pull out of the 2015 deal.
Trump will decide by May 12 whether to restore the sanctions, which would probably result in a reduction of Iranian oil exports. The price of oil has risen by about 6 percent in the past month thanks to expectations that the United States could do so.
"The rally seems to be intact and is looking for the next spark to push it higher. That spark could come from reinstituting sanctions. But not only is there the possibility of sanctions on Iran, but there's also the possibility of Venezuelan and Russian sanctions," Tradition Energy's McGillian said.
Venezuela's crude production has already tumbled from almost 2.5 million barrels per day (bpd) in early 2016 to around 1.5 million bpd due to political and economic crisis.
The European Union said earlier this month it could impose further sanctions on Venezuela if it believes democracy is being undermined there.
Moscow is holding off on taking retaliatory measures against the United States for imposing sanctions on Rusal, hoping the EU can persuade Washington to ease restrictions against the world's second largest aluminium producer further, sources told Reuters.
Trade data in Thomson Reuters Eikon shows seaborne imports of crude oil by Asia's main buyers will hit a record this month, a big portion going to slake China's voracious thirst.
By end-April, China will likely have taken in more than 9 million barrels per day (bpd) of crude - its most ever and nearly 10 percent of global consumption.
In the United States, production continued to grow, rising 46,000 bpd to 10.59 bpd last week, government data showed on Wednesday.
Soaring US output has made WTI crude around $6 per barrel cheaper than Brent and drawn exports to record highs over 2 million bpd.
With US output and exports surging, some analysts warn that the 20 percent climb in Brent prices since February is starting to look overdone.
"The market does look a little toppish," said Greg McKenna, chief market strategist at futures brokerage AxiTrader.