Brent oil steadied near $116 in choppy, thin trade on Friday as traders gauged the threat to supply from Middle East unrest and Libya fighting as well as concerns over demand in quake-hit Japan and debt-laden Europe.
A huge street protest against President Ali Abdullah Saleh in Yemen, Syrian demonstrations against the government of President Bashar al-Assad and protests in Bahrain and by Saudi Shi'ites kept concerns about the region's unrest in focus.
Rebel forces and those loyal to Libyan leader Muammar Gaddafi clashed as Western warplanes struck at armor used by the government to crush the revolt.
Investors eyed the threat to oil demand from Japan, where radiation fears escalated after workers suffered burns as they tried to cool a nuclear power station and the government sowed confusion over whether it was widening an evacuation zone.
Brent crude futures for May delivery were little changed, down 2 cents at $115.70 a barrel by 11:54 a.m. EDT (1554 GMT), having seesawed between $115.33 and $116.13.
U.S. May crude futures rose 6 cents to $105.66 a barrel, swinging between $104.50 and $105.90.
Brent and U.S. crude have stalled ahead of 2011 peaks. The May Brent may run into resistance ahead of its contract peak of $118.42, before approaching the 2011 front-month intraday high of $119.79 struck on February 24.
U.S. crude has been unable to move above its 2011 high of $106.95 struck on March 7.
The spread between Brent and the U.S. benchmark West Texas Intermediate crude, down 31 cents at $10.05 a barrel, was choppy on Friday, swinging from $9.83 to $11.24, but remaining well off its March 1 record above $17.
Middle East concerns are still in the forefront but the fundamental supply situation is not bullish, said Jacob Correll, commodity analyst at Summit Energy Services Inc in Louisville, Kentucky.
We are looking at many variables and it's tough to pinpoint at any given time which are the most important ones to consider.
With an expected summer demand boost and supply uncertainty, J.P. Morgan analysts headed by Lawrence Eagles raised oil price forecasts for 2011 for Brent and U.S. crude.
So long as ongoing problems in the Middle East continue to elevate risks of a further supply disruption, there is a strong likelihood of a price spike in the second quarter as the market demands additional oil to meet summer demand, J.P. Morgan said in a research note.
(Additional reporting by Gene Ramos in New York, Christopher Johnson in London and Alejandro Barbajosa in Singapore; Editing by Dale Hudson)