Oil prices steadied on Wednesday near six-month highs after data that showed U.S. stockpiles rose to their highest since October 2017, countering fears of tight supply resulting from OPEC output cuts and U.S. sanctions on Venezuela and Iran.
U.S. West Texas Intermediate crude futures settled 41 cents lower at $65.89 per barrel, down more than half a percent. The contract hit $66.60 a barrel on Tuesday, highest since Oct. 31.
Brent crude futures rose 6 cent to $74.57 per barrel, eking out a new six-month closing high. The international benchmark reached $74.73 a barrel on Tuesday, its highest intraday level since Nov. 1.
U.S. crude inventories rose 5.5 million barrels last week, the Energy Information Administration said, far more than analysts' forecast of an increase of 1.3 million barrels.
U.S. crude stocks jumped last week as imports increased. The nation imported an average 7.1 million barrels per day last week, up more than 1.1 million bpd from the previous week.
However, gasoline stocks fell by 2.1 million barrels, a larger-than-anticipated drop.
"What we're looking at is a headline number bearish on crude but supported somewhat by the gasoline number," said Phil Flynn, an analyst at Price Futures Group in Chicago. "Because of the sanctions that are coming down on Iran and the fact that there's going to be no waivers, it makes this number look more bullish."
Crude futures and prices for spot delivery rallied after the United States said on Monday it would end all exemptions for sanctions against Iran, demanding countries halt oil imports from Tehran from May or face punitive action. The move raised worries about tighter global oil supplies.
The United States must be prepared for consequences if it tries to stop Iran from selling oil and using the Strait of Hormuz, Iran's Foreign Minister Mohammad Javad Zarif warned on Wednesday.
China, Iran's biggest oil customer, has formally complained about the move.
The spot price surge put the Brent forward curve into steep backwardation, in which prices for later delivery are cheaper than for prompt dispatch.
The United States has said it saw Saudi Arabia as a partner to balance oil markets. But some analysts said the market remained fundamentally bullish.
"The factors that could lead to higher prices are overwhelming," said Carsten Fritsch at Commerzbank, adding a push towards $80 a barrel was more likely than a fall below $70.
Signaling no immediate action to counteract missing Iranian barrels, Saudi Energy Minister Khalid al-Falih said on Wednesday that his country's production in May would not vary greatly from previous months.
"Inventories are actually continuing to rise despite what is happening in Venezuela and despite the tightening of sanctions on Iran. I don't see the need to do anything immediately," Falih said.
He added that Saudi Arabia aimed to stick to its output quota fixed in a deal by OPEC, Russia and others, but that June numbers would be determined depending on customers' needs.
"If the market starts to appear too tight with a reduction in Iranian exports, Saudi has some capacity to ease the impact without breaking its OPEC+ pledge and endangering OPEC+ group commitment," Paul Sankey, an energy analyst at Mizuho, wrote in a note.
Meanwhile, crude output in the United States, which turned into the world's top producer last year, last week edged back to its record high at 12.2 million barrels per day, EIA data showed.
— CNBC's Tom DiChristopher contributed to this report.