Oil prices rose on Tuesday on evidence the global market was tightening as lower production by OPEC and other exporters drained stocks.
Meanwhile, an increase in drilling in the United States could keep a lid on prices.
Benchmark Brent crude was up 40 cents at 55.63 dollars a barrel by 0840 GMT. U.S. light crude was 40 cents higher at to 53.15 dollars.
Ministers from OPEC and big producers outside the group said on Sunday that 1.5 million bpd had already been cut.
The supply balance already appears to be tightening.
Bernstein Energy said global oil inventories declined by 24 million barrels to 5.7 billion barrels in the fourth quarter of last year from the previous quarter.
Still, this amounts to about 60 days of world oil consumption