A Reuters survey showed that the Organization of the Petroleum Exporting Countries in January achieved 82 percent compliance with its promised production cuts, well above most market forecasts.

"This is very high, a good number," an OPEC source said of the January compliance estimate.

The dollar .DXY was down by 0.9 percent versus a basket of currencies, boosting greenback-denominated oil. The dollar was on course for its biggest monthly decline since March.

Brent crude oil LCOc1 was up 67 cents a barrel at $55.90 by 11:22 a.m. EST. U.S. light crude CLc1 was up 78 cents at $53.41.

Both benchmarks have traded within narrow ranges over the last two months, since OPEC and other big exporters agreed to cut output by almost 1.8 million bpd in an attempt to clear a global glut.

"Direct oil market fundamental news seemed more mixed, with Iran claiming output in line with its OPEC agreement when the production level cited was still more than 100,000 bpd above its target and U.S. refiners still shutting more units for planned maintenance work," Tim Evans said.

Iran, which was allowed to raise output under the OPEC deal because sanctions had crimped past supply, pumped an additional 20,000 bpd.

"March Brent crude oil, February heating oil (ULSD) HOc1, and February RBOB gasoline futures RBc1 all expire today and so book squaring will also be a feature," Evans added.

The more active Brent crude for April delivery LCOc2 rose 93 cents to $56.25 a barrel.

U.S. shale output is slowly increasing, helping keep a lid on prices. Brent has been close to $55 a barrel and U.S. crude not far from $52.50 for most of January.

Following months of increased drilling, U.S. oil production C-OUT-T-EIA has risen by 6.3 percent since July last year to almost 9 million bpd, according to data from the U.S. Energy Information Administration.

The strength in Brent versus U.S. crude also pushed the spread between the two contracts to the widest in nearly a year.