At the same time, production in the United States has been rising faster than expected. Output has also risen in Libya, despite continuing warfare, and it has held up better than expected in another troubled country, Venezuela. Volumes of oil held in storage tanks around the world are beginning to build again, raising fears of a renewed glut, analysts say.

What has been the impact of sanctions on Iran?

The sanctions have had less effect on Iranian output than some analysts had predicted, but expectations may have been too dire. The measures, which impose penalties on companies buying Iranian oil, came into effect on Nov. 5. Buyers had been expected to reduce purchases of Iranian crude oil before the sanctions, but that activity seems to have curbed Iran’s output only modestly. For instance, OPEC reported that Iranian production in October was down 4.5 percent from the previous month, to about 3.3 million barrels a day.

Some background on why the impact has been muted: The Trump administration granted temporary waivers to Iran’s largest customers, including China, India and Japan. Oil traders took the administration’s generosity to mean that the eventual cuts to Iranian exports might be less than expected. “The market was quite surprised to see that waivers were granted,” said Homayoun Falakshahi, an Iran analyst at Wood Mackenzie, an energy research firm.

Mr. Falakshahi said the granting of exemptions to Japan and South Korea, which had stopped buying Iranian oil, was particularly striking. It might indicate, he said, that the administration’s priorities leaned more to keeping prices low for American consumers than squeezing Iran. If so, the strategy seems to be working. The price of regular gasoline in the United States on Tuesday was $2.61, compared with $2.85 a month earlier, according to AAA.

What will shape prices in the next few weeks?

When OPEC members meet in Vienna next month, analysts expect the group to announce production cuts of around one million barrels a day, about 1 percent of world supplies.

There is little doubt that the Saudis can make cuts of this scale. After all, they have lifted production by almost 700,000 barrels a day compared with their average output in 2017.

Saudi Arabia, which tries to avoid taking the pain on its own, may struggle to persuade producers like Russia and Iraq to join in making cuts, analysts said. The Saudis may also need to navigate a tricky path between the pressures from the Trump administration for lower oil prices and their economy’s need for higher revenues.