Brent crude will average $55/bbl in 2015, $65/bbl in 2016 and $80 in the medium term.
Russia's Finance Minister Anton Siluanov says falling oil prices have created a $180bn shortfall in revenues to date.
Markets have been reacting to the World Bank cutting 2015 growth forecast to 3% from 3.4%.
Premier Oil also said it expects to spend around 40% less, or $600m, on planned development this year.
On the higher side, it has to break $65 to confirm a reversal.
Oversupply and weak demand continue to plague global crude oil market.
Prince Alwaleed bin Talal defends Saudi decision not to cut production to boost prices.
Rio Tinto has waited patiently for over a decade to begin mining at Bunder, in the Madhya Pradesh state.
Crude oil prices have ended down for the past seven consecutive weeks on oversupply concerns.
Oil rout continues as key producers show no signs of slashing output amid global glut.
A drop in oil prices has put money in consumers' pockets, says Minneapolis Federal Reserve boss Narayana Kocherlakota.
Low prices also raise the risk of geopolitical instability, warns commodity hedge fund manager Andrew J Hall.
President Xi expects two-way trade between China and Latin America to rise to $500bn within 10 years.
Suhail bin Mohammed al-Mazrouei says crude prices could recover if non-Opec producers "act rationally".
China, in pursuit of cheap commodities, could be forced to play by free trade rules.
Crude oil has lost more than half of its value since June 2014.
Large firms such as Schlumberger, Halliburton and Baker Hughes can beat slump.
US crude output at record level as Saudi Aramco adopts dual pricing strategy
US West Texas Intermediate oil falls to five-and-a-half year low as producers boost production.
Petrol prices in the UK are falling closer to £1 a litre as the UK's supermarket giants cut prices.
Prices heading towards £1 per litre as major supermarkets seek to lure customers with cheap petrol.
In 2013 and 2012 oil prices averaged $100/bbl.
A stronger US dollar and concerns surrounding a global glut continue to put pressure on oil prices.
Iraq and Russia post bumper production in late 2014 despite subdued oil price.
Rate of expansion as falling oil prices and Western economic sanctions take toll.
Libyan oil exports are down 300,000 barrels per day since the fighting reached the oil crescent.
The only currency in the gainers list is the US dollar and the only metal is palladium.
Analysts say Brent crude could drop to $55 a barrel early next year.
Libya has descended into violence as Islamists and tribes fight for power in the post-Gaddafi era.
Armed factions in Libya are battling for control of the Opec member.