OPEC's oil production dropped in May by 70,000 bpd to 32.00 million bpd on the back of outages in Nigeria and a continuous decline in Venezuela that dragged the cartel's total production to the lowest level since April 2017, according to the monthly Reuters survey.
West Texas Intermediate for July delivery traded at $66.99 a barrel on the New York Mercantile Exchange, down $1.58, at 9:16 a.m.in New York.
For the week, WTI is on track for a 1.5% fall, adding to last week's almost 5% decline, while Brent is set to rise 1.3%, widening the spread between the two benchmarks.
OPEC speculation, rising production and transport bottlenecks are combining to put a lid on United States oil prices.
Hedge funds and other money managers cut their bullish wagers on USA crude futures and options, according to data released on Friday, as oil prices slumped on oversupply fears.
Meanwhile, according to the Weekly Petroleum Status Report by EIA on Thursday, U.S. commercial crude oil inventories, excluding those in the Strategic Petroleum Reserve, decreased by 3.6 million barrels during the week ending May 25.
Over the last four weeks, motor gasoline product supplied averaged about 9.7 million barrels per day, up by 0.8 percent from the same period previous year.
Crude oil futures lost more ground on Friday, with the USA market set for a second week of decline on pressure from record USA production and expectation that the Opec cartel will increase output.
"We are going into summer, the high demand season, and I think we are going to see a fall in USA crude oil inventories, but shale oil output is growing".
USA crude production rose in March by to 10.47 million barrels per day (bpd), a monthly record, the Energy Information Administration said on Thursday.
Global benchmark Brent fell 77 cents to US$76.79 a barrel.
US President Donald Trump also urged Opec to increase production which both Kapadia and Kelty believe had an important impact on driving prices down. According to services group, Baker Hughes, another 2 rigs were activated last week to look for oil in the U.S., taking the figure to 861 last week, the highest for more than three years.
Saudi Arabia and Russian Federation said last week that they are considering boosting production to ease potential supply disruptions in Iran and Venezuela. Output has risen for 14 straight weeks as drillers put more rigs to work.
Kazakhstan is consulting other producers on the potential easing of a 2016 oil output reduction agreement between the Organisation of the Petroleum Exporting Countries (OPEC) and non-OPEC members, Kazakh Energy Minister Kanat Bozumbayev said recently.