Oil prices popped on Wednesday as the U.S. dollar fell from its high for the year after the Federal Reserve left its benchmark interest rate unchanged.
The rising value of the dollar since mid-April and soaring U.S. supplies have helped check further oil price gains, traders said. A weaker greenback makes commodities priced in dollars, including crude oil, more affordable to holders of other currencies.
"Yesterday, the sell-off in crude was really driven by that spike over 92 in the dollar index, so we're giving some of that back today," said John Kilduff, founding partner at energy hedge fund Again Capital.
U.S. West Texas Intermediate (WTI) crude futures finished Wednesday's session up 68 cents, or 1 percent, at $67.93 per barrel. Brent crude oil futures were up 22 cents at $73.35 per barrel at 2:28 p.m. ET.
The market mostly shrugged off a surprise build in U.S. crude inventories because the move was largely concentrated on the U.S. West Coast.
Crude stockpiles posted a surprise build of 6.2 million barrels in the week, according to the U.S. Energy Information Administration. Nearly 5 million barrels were concentrated on the West Coast.
"That's why the market isn't reacting that much, because sometimes the West Coast numbers are erratic and usually when you get a big build in the West Coast, it's followed with a big draw the next week," said Phil Flynn, an analyst at Price Futures Group.
"The market is putting that in perspective," he said. At the same time, demand for distillate fuels like diesel was strong, he said, offsetting the downward pressure on crude.
U.S. production has jumped by a quarter in the last two years to 10.6 million bpd. The United States has overtaken Saudi Arabia to become the world's second-biggest crude producer after Russia.
"The major factor acting as a drag on long-term upside potential is the surge in U.S. shale supply. Concerns over the U.S. shale engine may have recently been put on the back burner, but this reprieve is not expected to last," PVM Oil Associates strategist Stephen Brennock said.
Concerns that the United States will reimpose sanctions on Iran continue to underpin the market. Oil prices spiked on Monday after Israeli Prime Minister Benjamin Netanyahu pressured the United States to scrap the 2015 Iran nuclear deal, but fell sharply on Tuesday as the dollar rose and the market's jitters over Netanyahu's speech eased.
"Geopolitical noise remains loud and in part pushed oil prices towards $75 per barrel," said Norbert Ruecker, head of commodity and macro strategy at Julius Baer.
"The elevated uncertainty suggests volatile but range-bound oil prices going forward."
Iran's oil exports hit 2.6 million barrels per day (bpd) in April, the Oil Ministry's news agency SHANA reported on Tuesday, a record since the lifting of sanctions in 2016, with China and India buying more than half of Iran's oil.
Iran, a member of OPEC, re-emerged as a major oil exporter in January, 2016 when international sanctions against Tehran were lifted in return for curbs on Iran's nuclear program.
The United States, however, has expressed doubts over Iran's sincerity in implementing those curbs and President Donald Trump has threatened to re-impose sanctions. Trump will decide by May 12 whether to restore U.S. sanctions on Tehran, which would likely result in a reduction in its oil exports.
"The expectation that the U.S. will leave the sanctions waivers is leading Iran to sell as much as it can," Petromatrix strategist Olivier Jakob said.
Some analysts, however, said there was a risk that prices could slump as too many oil traders were betting on renewed sanctions.
"If the geopolitical tension subsides or results in a smaller supply disruption than currently priced in, we are likely to see a sharp pull-back in investor positioning and an even sharper correction in oil prices than the $5 or so that might be warranted even as macro uncertainties persist," U.S. bank Citi said in a note to investors.
— CNBC's Tom DiChristopher contributed to this report.