Brent crude lost 50 cents, or 0.7%, to $76.67 a barrel, while U.S. West Texas Intermediate (WTI) crude shed 16 cents, or 0.2%, to $71.85.
Oil prices rose after the company announced the closure, which occurred at about 8 p.m. CT Wednesday (0200 GMT Thursday), but market sentiment has since shifted.
While U.S. crude inventories fell last week, gasoline and distillate inventories surged, adding to concern about easing demand.
Both Brent and U.S. crude hit 2022 lows on Wednesday, unwinding all the gains made after Russia's invasion of Ukraine exacerbated the worst global energy supply crisis in decades and sent oil close to its all-time high of $147.
The queues suggest that "available supply from the Black Sea is already affected by the punitive measure," said Tamas Varga of oil broker PVM.