Crude oil inventories in the U.S. decreased last week, while crude production and imports increased, according to the Energy Information Administration (EIA) on Thursday.
Commercial crude stocks fell by 2.2 million barrels, or 0.4 percent, to 533.4 million barrels for the week ending April 7, the EIA said.
The market expectation was an increase of 0.09 million barrels.
"... there was also a 0.6 million barrel draw in the Strategic Petroleum Reserves, some of which is likely to have gone into commercial storage," Joseph Oyegoke, a commodities economist at London-based Capital Economics, said in a note.
Strategic Petroleum Reserves, which are not included in commercial crude stocks, decreased by 0.6 million barrels, or 0.1 percent, to 691.5 million barrels last week, according to the EIA.
"Meanwhile, inputs to refineries were up again, which also helped draw down crude oil inventories," Oyegoke said.
Refineries are the largest source for crude demand, as they withdraw from commercial inventories to produce gasoline or other petroleum products.
After the decline in crude stocks against market expectation, oil prices saw slight gains.
American benchmark West Texas Intermediate rose to $53.62 per barrel around 15.00 GMT on Wednesday, while international benchmark Brent crude reached $56.39 a barrel.
Crude oil production in the U.S., on the other hand, continued to increase.
American producers added 36,000 barrels per day (bpd) last week as the country's total domestic output reached 9.23 million bpd for the week ending April 7, the EIA figures showed.
The U.S.' oil imports also increased slightly, by 28,000 bpd to reach 7.88 million bpd last week.
By Ovunc Kutlu in New York