"This year, the main story has been the political risks story," Global Insight oil analyst Simon Wardell said.
In 2005, however, crude prices raced ahead owing to strong demand in China and the United States, as well as lower production caused by hurricane damage to oil installations in the Gulf of Mexico.
This year, amid an already tight supply situation, concerns about geopolitical instability in producer regions has fuelled higher prices.
The threat of UN sanctions against Iran over its nuclear stand-off with the West led the Islamic Republic to hint at threatening disruption to its oil exports, which in turn sent prices surging.
In Nigeria, meanwhile, militant attacks on oil facilities in the Niger delta slashed the African country's output by up to a third.
Prices won support also from the July conflict between Lebanon and Israel, worsening violence in Iraq and a hardening of relations between the US and South American oil giant Venezuela.
And despite North Korea not bei