Brent crude fell on Tuesday, ending 2013 almost unchanged following a year in which traders balanced a spate of supply disruptions from Middle East and Africa against surging output from the United States.

Weighed down by expectations oil shipments from some shuttered Libyan ports would resume soon, Brent finished the year just 31 cents its end-2012 level of $111.11 a barrel. The international benchmark traded in a $22 range from $96.75 to $119.17 this year, the narrowest band since 2006.

U.S. crude closed the year 7.2 percent firmer as traders headed into 2014 eyeing improving demand, the end of the Federal Reserve's monetary stimulus and the dramatic overhaul of the world's largest oil market caused by the shale revolution.

U.S. crude traded within a $27 range throughout 2013, also the narrowest band since 2006.

Brent's premium to U.S. crude, or West Texas Intermediate (WTI) traded at just over $12 a barrel on Tuesday, down from more than $19 a barrel at the end of last year. In July, the two benchmarks reached parity and WTI briefly rose above Brent for the first time since 2010.

"We saw quite a lot of drama in those spreads in 2013; that was the trade of the year," said Katherine Spector, head of commodities strategy at CIBC World Markets.

"It's still trying to find that equilibrium. I think we'll continue to see WTI trade $10 to $12 under Brent."

Brent crude fell 41 cents on the day to end 2013 at $110.80 a barrel, 0.3 percent lower on the year.

U.S. oil fell 87 cents on Tuesday to end at $98.42 a barrel, after closing 2012 at $91.82 a barrel.

"There's been some optimism about the potential return of supplies from South Sudan and Libya, and that's probably what's helped Brent down," said Amrita Sen, chief analyst at consultants Energy Aspects.

Violence in South Sudan has reduced crude output by about a fifth to 200,000 barrels per day (bpd), but the South Sudanese government and rebels loyal to former Vice President Riek Machar agreed on a ceasefire on Tuesday as they prepare for talks to end the bloodshed.

In Libya, where protests have slashed output to less than 250,000 bpd from 1.4 million bpd in July, the Sarir and Messla oilfields are up and running. But the Hariga oil port they connect with, which officials had said was to open soon, needs to reopen before exports can resume.

In addition to the Libyan disruptions, unrest in Iraq and tensions between Iran and the West over Tehran's disputed nuclear program supported crude prices throughout 2013.

These factors have offset concerns over a weak demand outlook in industrialized nations and a slowdown in consumption in China, the world's second-biggest oil consumer.

Chris Tevere, senior strategist at Gain Capital, said the Middle East remained a focus for 2014.

"The key concern is still 'Are there any further troubles brewing in the Middle East?'"

(By Anna Louie Sussman and Matthew Robinson; Additional reporting by Joshua Franklin in London and Manash Goswami in Singapore; Editing by Angus MacSwan, Dale Hudson, Andrew Hay and Marguerita Choy)