Oil prices rose in volatile trade on Thursday, with investors less worried about prospects for the global economy after the last pre-vote opinion polls showed Britain was likely to remain in the European Union.
Oil prices were also supported by market intelligence firm Genscape's report of a drawdown of nearly 1 million barrels at the Cushing, Oklahoma storage base for U.S. crude futures during the week to June 21, traders who saw the data said.
Brent crude was down 6 cents, or 0.12 percent, at $50.85 a barrel. During the session it rose as much as 2 percent, hitting an intra-day high of $50.90.
U.S. crude settled up 98 cents, or 1.99 percent, at $50.11 a barrel, and last traded up 90 cents, or 1.83 percent at $50.03.