"The ever-expanding US supply continues to pose significant downside risk to oil prices", said Stephen Innes, head of trading for Asia/Pacific at futures brokerage OANDA in Singapore.
Oil has struggled to recover losses from last month's broader market slump after topping $66/bbl in January.
U.S. West Texas Intermediate and international-benchmark Brent crude oil futures are trading mixed early Monday.
"Venezuela is obliged to supply barrels to China and Russian Federation to pay back debts, so not too much is left for others, mainly India", Ehsan Ul-Haq, director of crude oil and refined products at consultancy Resource Economist, told Reuters.
Weighing on global markets has been a relentless rise in US crude oil production C-OUT-T-EIA, which has soared by nearly a quarter since mid-2016 to 10.37 million bpd, overtaking output by top exporter Saudi Arabia.
"Oil prices moved lower. after (the) Energy Information Administration published a report that crude production from seven major USA shale plays is expected to see a climb", said Stephen Innes, head of trading for Asia/Pacific at futures brokerage OANDA in Singapore.
The reduction came as gross short positions on the New York Mercantile Exchange climbed to their highest level in almost a month.
All loadings at the Libyan oil export port of Zawiya, which exports crude from the 308,000-barrel per day El Sharara field, have stopped due to a strike, a Libyan website said. Total volume traded was about 53 percent below the 100-day average.
Brent for May settlement added 1 cent to $64.96 a barrel on the London-based ICE Futures Europe exchange.
Crude oil prices reached $65 on Monday after a drop in prices earlier in the year. The global benchmark widened to a $3.89 premium to May WTI.
U.S. Shale production is expected to rise above 11 million bpd by late 2018, taking the top spot from Russian Federation, according to the International Energy Agency (IEA).
The EIA last week also raised its production estimate for the full year, saying it expects total US crude production to rise by 1.4 million barrels a day in 2018. Meanwhile, stockpiles at Cushing, Oklahoma, the delivery point for WTI futures, probably were little changed after 11 straight weeks of declines. Gasoline futures in NY are down 0.2% at $1.8895 a gallon.