Oil prices strengthened on Friday but stayed below recent highs as global supplies remained tight and the market awaited news from Washington on possible new US sanctions against Iran.
Markets will remain skittish as the May 12 deadline to rectify the deal approaches, ANZ Research said in note.
"Overall, we continue to trade a waiting game for the USA decision on Iran, waiting to have sanction headlines trigger some frenzied buying", said Olivier Jakob, managing director of energy consultancy PetroMatrix.
US government data on Wednesday showed a 6.2-million-barrel jump in crude inventories last week.
ICE Brent crude futures, the benchmark for oil prices outside the United States, fell 0.87% to $74.04 a barrel.
West Texas Intermediate crude for delivery in Midland slid for a fouth day on Thursday to hit their lowest in more than three-and-a-half years. The contract was set to end the week down 0.3 per cent.
United States light crude was 5c lower at $68.38 and set for a gain of 0.3% for the week.
The Iranian Foreign Minister said on Thursday that the USA demands for a change in the nuclear deal are unacceptable.
Rosenberg resigns from Senate
None of the seven Republicans in the Senate had publicly called for Rosenberg's resignation as of midday Thursday, though Rep. Senate President Harriette Chandler, who replaced Rosenberg as president, called the report "thorough and troubling".
These dynamics caused Rob Thummel, portfolio manager at Tortoise Capital, to remark, "The margin for error right now is just so low in the oil market that you can't just take supply off the market".
Trump has said that unless European allies rectify the "terrible flaws" in the worldwide accord by May 12, he will refuse to extend US sanctions relief for the oil-producing Islamic Republic.
Trump has all but made a decision to withdraw from the 2015 Iran nuclear accord by May 12, sources said, though exactly how he will do so remains unclear. But they have also started work on protecting EU-Iranian business ties if the USA president makes good on a threat to withdraw, six sources told Reuters.
In January 2016, Iran resumed its role as a major oil exporter when worldwide sanctions against Tehran were lifted in exchange for a curtailment of nuclear program.
Although geopolitical risks trump fundamentals right now, oil prices could react later today to the Baker Hughes rig count data, a proxy for USA production growth, and to the US dollar movements after the U.S.jobs report that showed unemployment rate dropping to an 18-year low to 3.9 percent, but non-farm payrolls growth missing expectations.
Surging production in the Permian shale basin is outpacing pipeline capacity, while local refining issues have exacerbated oversupply in the region. Because most oil market forecasts assumed OPEC would adhere closely to the production targets, and not under produce, most analysts predicted at the start of 2018 that the oil market would see inventory builds again in the second quarter.
OPEC's ability to be unified in its output reduction efforts is crucial at a time when Russian Federation, the world's largest producer; and the US are pumping oil at near record levels. The weekly rig count from Baker Hughes, an indicator of forward-looking production, is scheduled to be released at 1 p.m. on Friday.