Oil prices tested the $50-per-barrel mark on Thursday as production outages brought a faster-than-expected recovery to an oversupplied market.
Global benchmark Brent crude oil was down 35 cents at $49.40, having earlier risen as high as $50.51 in intraday trading.
U.S. crude futures settled down 0.16 percent, or 8 cents, at $49.48 a barrel, and were last down 22 cents at $49.34 a barrel, after rising to $50.21, the highest since mid-October.
The daily settle came as presumptive Republican presidential nominee Donald Trump criticized environmental regulations on oil and coal.
While a crude glut could grow in coming months if demand stalls, wildfires in Canada's oil sands, unrest in the Nigerian and Libyan energy sectors, and a near economic meltdown in OPEC member Venezuela have knocked out nearly 4 million barrels per day in immediate production.