By Christopher Alessi and Jenny W. Hsu 

Oil prices were mainly flat Monday morning as investors worried that an OPEC meeting in St. Petersburg would likely fail to alleviate concerns over the global supply glut.

Brent crude, the global benchmark, was up slightly, by 0.35%, to $48.24 a barrel, in London midmorning trading. On the New York Mercantile Exchange, West Texas Intermediate futures were trading up 0.33%, at $45.94 a barrel.

Prices had closed down about 2.5% on Friday in their seventh-lowest settlement of the year, in anticipation of the OPEC meeting.

The Organization of the Petroleum Exporting Countries is meeting with big producers outside the cartel, including Russia, to discuss the effectiveness of an output-cutting deal struck last year. The agreement was meant to drain the global oversupply of crude and help push prices upward, though the glut has persisted and prices have remained stubbornly low.

Initially, investors had been cautiously optimistic that participants might force Libya and Nigeria--OPEC members exempt from the deal--to start reducing output or mandate larger cuts for all the players. But now it is "unlikely we will see any bullish measures from the meeting," said Andy Sommer, a senior energy analyst at Axpo Trading.

"Faith in the oil market rebalancing is waning by the day and the sooner the Saudis admit the need to do more, the sooner prices can begin their journey on the road to recovery," analysts at PVM wrote in a note Monday morning, suggesting Saudi Arabia--OPEC's largest member--would have to further cut production to make the deal effective.

Global prices have been in the doldrums for three years as supply has outpaced demand, sending stockpiles to record levels. Even though the OPEC-led curtailment deal has been in force since January, global inventories have barely fallen, pressuring prices.

At the same time, Axpo's Mr. Sommer said he expected prices to remain "range bound" because data out of the U.S. showing a drop in inventories was "supportive for prices."

Analysts will be looking ahead to weekly U.S. inventory numbers to gauge whether stocks have fallen further.

Nymex reformulated gasoline blendstock--the benchmark gasoline contract--was down 0.18%, to $1.5315 a gallon. ICE gas oil changed hands at $450.75 a metric ton, down 0.50% from the previous settlement.

Write to Christopher Alessi at christopher.alessi@wsj.com and Jenny W. Hsu at jenny.hsu@wsj.com

(END) Dow Jones Newswires

July 24, 2017 06:06 ET (10:06 GMT)