By Vijaykumar Vedala and Ratul Ray Chaudhuri
(Reuters) - Oil price forecasts have collapsed in the wake of OPEC's decision not to cut output despite a global glut, Reuters monthly poll showed on Thursday.
The survey of 31 economists and analysts, conducted after the Organisation of the Petroleum Exporting Countries meeting on Nov. 27, forecast North Sea Brent crude would average $82.50 (52.6 pounds) a barrel in 2015, down $11.20 from last month's poll.
That is the biggest downgrade in average forecasts since the global economic crisis in 2008 and compares with an average price of $102.70 for Brent so far this year. The poll forecast Brent would average $87.40 in 2016.
Oil prices have fallen by more than a third since June with Brent reaching a five-year low on Monday of $67.53 a barrel and U.S. crude touching $63.72.
Twenty-one of the 29 analysts who contributed for both the October and the latest poll slashed their forecasts. Fifteen analysts said they changed their forecasts after the OPEC meeting.
"OPEC's decision to maintain its production entrenches a surplus," said Gareth Lewis-Davies, strategist at BNP Paribas. "At current levels of OPEC crude output, the market faces 1.5 million to 2 million barrels per day of surplus."
In Reuters monthly oil price poll in June, analysts had forecast Brent would average $104.80 in 2015.
Italy's Nomisma Energia had the lowest 2015 Brent forecast in the latest Reuters poll at $69.18 a barrel, while U.S. based brokerage Sanford C. Bernstein had the highest forecast at $104.
"OPEC's abandoning of oil market management last Thursday feels like one of those seminal points in the history of oil," said Credit Suisse analyst Jan Stuart, who cut his 2015 Brent price forecast by $16.25 to $75.25.
But some analysts were more cautious.
"I think we should not jump into conclusions and adjust forecasts already when markets are in such a panic mode," said senior energy economist Hans van Cleef of ABN AMRO, who kept a $90 Brent forecast for 2015.
The poll forecast U.S. light crude would average $78.00 a barrel next year, down $10 from October's consensus. WTI has averaged $96.00 in 2014.
Brent's premium
(Editing by Christopher Johnson and William Hardy)