U.S. crude stockpiles rose by 3.6 million barrels in the week to Nov. 23, exceeding expectations. After falling to 2½-year lows in September, crude stocks have risen 14 percent with 10 straight weeks of increases.
"The market continues to come under pressure due to worries of a supply glut and slowing global demand growth," said Gene McGillian, vice president of market research for Tradition Energy in Stamford, Connecticut.
"It's hard to get more bearish after this report after we wiped out more than 30 percent of our value in the last two months."
The price of Brent has dropped by more than 30 percent from a four-year high above $86 in early October. Investors sold oil over worries about slowing economic growth in 2019 and Washington's decision to grant several waivers to importers of Iranian oil after re-imposing sanctions on that nation.
Crude's drop since October is on a par with the 2008 price crash and steeper than that of 2014-2015, both of which prompted OPEC to agree output curbs to support the market.
The steady build in U.S. crude stocks is partly due to seasonal refining maintenance, but domestic production also has surged to a record 11.7 million barrels a day. U.S. stockpiles sit at 450 million barrels, most in a year, adding to worries about a return of a worldwide supply glut.