By Christopher Alessi and Alison Sider 

Oil prices were mixed Monday, as investors weighed further crude supply disruptions in Venezuela against the prospect that the European Union will help keep Iran's oil flowing.

U.S. crude futures rose 33 cents, or 0.46%, to $71.61 a barrel on the New York Mercantile Exchange. Brent, the global benchmark, fell 16 cents, or 0.2%, to $78.35 a barrel on ICE Futures Europe.

Brent prices came under pressure as Iran and the EU tried to salvage the 2015 international nuclear agreement. Iranian officials vowed over the weekend to uphold the pact curbing its nuclear activities if the EU could offset renewed U.S. sanctions.

"That could mitigate any impacts on Iranian exports," said Andy Lipow, president of Lipow Oil Associates.

The planned reimposition of U.S. economic sanctions on Iran following President Donald Trump's decision earlier this month to withdraw from the 2015 agreement has bolstered oil prices lately.

Analysts estimated that anywhere from 400,000 to 1 million barrels a day of Iran's current 2.4 million barrels a day of crude exports could be at risk. International oil firms like France's Total SA have already announced their intention to abandon planned energy projects in Iran following the U.S. decision.

But the victory of Venezuela's far-left president, Nicolás Maduro, on Sunday in a race that was called illegitimate by the opposition and foreign governments paves the way for the imposition of stricter international sanctions, including potential new U.S. measures targeting the country's already-hindered oil industry.

"The specter of U.S. oil sanctions on the embattled Latin American producer now looms large as Washington strives to tighten the financial noose," according to Stephen Brennock, analyst at brokerage PVM Oil Associates Ltd.

Venezuelan crude output fell 50,000 barrels a day month-on-month in April, to stand at 1.42 million barrels a day, according to the International Energy Agency's latest monthly oil market report.

"Washington has already enforced economic measures that impair Venezuela's ability to finance projects and pay back debt. With the oil sector spiraling deeper into crisis, it is possible that capacity could fall by several hundred thousand barrels a day by the end of the year," the IEA report noted.

Both Iran and Venezuela are members of the Organization of the Petroleum Exporting Countries, which -- in coordination with other producers outside the cartel like Russia -- has already been holding back crude output by around 1.8 million barrels a day since the start of last year. The cuts, which are set to expire at the end of 2018, were part of an effort to rein in a global supply glut that had weighed on prices since late 2014.

But excess supply has now largely been mopped up, with commercial petroleum stocks at their lowest level in over three years and prices having largely recovered. Brent last week temporarily breached the symbolic $80-a-barrel threshold for the first time since 2014.

Gasoline futures fell 0.04% to $2.2293 a gallon. Diesel futures fell 0.37% to $2.2572 a gallon.

Write to Christopher Alessi at christopher.alessi@wsj.com and Alison Sider at alison.sider@wsj.com

(END) Dow Jones Newswires

May 21, 2018 10:59 ET (14:59 GMT)

Copyright (c) 2018 Dow Jones & Company, Inc.