Market confidence faltered after news of another big rise in U.S. crude inventories that have built steadily to record highs as USA oil production has grown this year.
Brent crude oil was down 10 cents at US$52.09 a barrel by 1445 GMT, after falling 1.7% on Thursday and 5% the day before in its biggest percentage decline in a year. It fell below $50 on Thursday for the first time since December.
"Record high inventory levels are reason for pause, but we believe that the market is overly focused on United States stocks".
USA crude prices edged up on Friday after dropping below $50 per barrel for the first time since December in the previous session, pressured by concerns that a global supply glut is proving stubbornly persistent.
After having dipped 5 percent on Wednesday, oil prices continued plunging on Thursday by more than 2 percent, as speculators have started exiting the almost record long positions in oil futures that they had amassed.
Brent for May settlement fell as much as $1.51 a barrel, or 2.8 percent, to $51.60 a barrel on the London-based ICE Futures Europe exchange.
The Organisation of the Petroleum Exporting Countries and other exporters including Russian Federation agreed a year ago to cut output by around 1.8 million barrels per day in the first half of 2017, but so far the move has had little impact on inventory levels.
"I still think we will stick in a fairly narrow range with the current levels reflecting the average price for the remainder of the year and a bottom of around $40 and a top end of somewhere around $60", said Chris Gaffney, president of EverBank World Markets in St. Louis, Missouri.
Options trade also reflected hopes that prices would recover. The global benchmark crude traded at a premium of $2.36 to May WTI.
USA drilling has also picked up, with producers planning to expand crude production in North Dakota, Oklahoma and other shale regions, while the Permian, America's largest oilfield, has seen output jump. The Permian, America's largest oilfield, has seen output jump.
"The discussion will now center around whether or not Saudi Arabia is willing to give back market share to USA producers. or are they ready for yet another round of the market share war", Dominick Chirichella, senior partner at the Energy Management Institute in NY, told Reuters on Thursday.