Oil markets fell more than 2 percent on Thursday, wiping out the previous day's gains on profit-taking and after a run-up in the dollar, which weighed on prices of commodities denominated in the greenback, Reuters reported.
On Wednesday, oil settled up about 2 percent, with U.S. crude closing at its highest level in 15 months, after a large and unexpected draw down in U.S. crude stocks.
"After the big run, I think it is very reasonable", Kyle Cooper, analyst at ION Energy in Houston, told Reurters, referring to the price retreat on profit-taking.
The front-month in Brent crude was down $1.29, or 2.4 percent, at $51.38 per barrel by 10:55 a.m.
The front-month in U.S. West Texas Intermediate (WTI) crude, which expires at Thursday's settlement, was off by $1.15, or 2.2 percent, at $50.45. On Wednesday, it hit a July 2015 high of $51.93.
WTI's more-active second-month position slid $1.20 to $50.62.
The U.S. government has reported crude inventory draws in six of the past seven weeks, surprising analysts who usually expect a rise at this time of year from refinery maintenance.
In the latest week to Oct. 14, there was a drop of 5.2 million barrels, while refineries only ran at 85 percent. Lower crude imports were responsible for the draws, data showed.
Energy monitoring Genscape added to U.S. crude's improved outlook on Thursday by reporting a drop of nearly 1.25 million barrels in crude stockpiles the Cushing, Oklahoma delivery hub for WTI futures for the week to Oct. 18.
While oil markets were down in the latest session, they were still up about 13 percent from Sept. 27 when OPEC announced its first planned output cut in 8 years to rein in a global glut that has halved prices from mid-2014 highs above $100 a barrel.