Oil slipped after reaching a record near $120 yesterday on profit taking and as the Grangemouth refinery strike ended in Scotland.
Losses were limited, however, with constant jitters over supply from Nigeria.
New York-traded West Texas Intermediate crude for June delivery fell 81 cents to 117.94 by 9.23am. Meanwhile London Brent crude for June delivery fell 92 cents to $115.82.
The Grangemouth refinery reopened from a two-day strike that had shut down a pipeline that carries about half of Britain's crude supply.
Yesterday, New York futures reached a record $119.93 per barrel.
Investors are still fretting over production losses in Nigeria, Africa's biggest crude supplier, after a spate of militant attacks on oil installations in the country and a strike at ExxonMobil's affiliate there.
ExxonMobil's Nigerian division MPN earlier confirmed that a five-day strike by white-collar employees had caused a cut in output, but declined to give a figure for the loss.
"In Nigeria, the supply situation gets no better," said MF Global senior energy broker Rob Laughlin. "There appears little dialogue in this dispute so far but the Nigerian government will be holding talks with officials from the Pengassan Union later today," he added.
Looking ahead, the market will focus on US supply with the world's biggest energy consumer set to release weekly inventory figures tomorrow.