Oil prices rose for a third straight session Tuesday on growing confidence that OPEC will deliver a promised production cut next week after delegates reported good progress in informal talks and analysts backed the logic of a deal.

Brent Crude futures for delivery in January traded 1.8% higher at $50.62 while West Texas Intermediate futures for delivery in January added 1.6% to change hands at $49.04 by 10:30 GMT in London.

WTI, the U.S. benchmark, and Europe's Brent have added about 12% since closing at one month lows on November 14, rising to their highest marks since the end of October..

Informal meetings of OPEC members to discuss quotas began this week in Vienna ahead of a formal meeting on November 30 at which members have pledged to cut production by about 5% to between 32.5 million and 33 million barrels of oil per day. Country representatives appeared bullish about the prospects for a deal on Monday evening, telling reporters outside the meeting that progress on individual country quotas had been made.

Oil prices also benefited from a bullish note from Goldman Sachs, which claimed that the rationale for an OPEC cut had grown over the past two months as stronger than expected demand growth meant it was now within the power of OPEC to quickly rebalance the market.

"With greater certainly that deficits will finally materialize (in the second half of next year), there is now a stronger economic incentive for OPEC producers to prevent a further rise in inventories in 1H17 and instead act to normalize the current high level of inventories through a short duration production cut," Goldman analysts including Damien Courvalin and Jeffrey Currie wrote.

Goldman suggested a cut in production could lead to "backwardation,"  a term describing a situation where the spot price is higher than the forward price. That would enable OPEC producers to boost short term profits while while keeping longer-term prices low enough to discourage higher priced players, such as U.S. shale gas providers, out of the market.

Goldman tipped average oil prices of $52.50 a barrel for WTI over 2017. That is unchanged from the bank's earlier forecast, though it now expects prices to rise earlier in 2017 then fall over the second half as OPEC production resumed growth and U.S. shale producers reacted to prices above $55.

The major risk to an OPEC accord remains a political breakdown, notably between regional political and oil rivals Saudi Arabia and Iran. Analysts said they had been encouraged by the Saudi's steadfast commitment to the price cut, despite Iran's insistence that it should be excluded from output reductions.     

"The single most important country in OPEC, Saudi Arabia, wants it (a cut)," RBC Capital Markets said on Tuesday. "Another fall in oil prices could plunge the Kingdom further into the red, imperil key initiatives (e.g., Aramco IPO), and raise the prospect of higher borrowing costs."

Rising oil prices have had a knock on effect on European oil company stocks. Europe's biggest producer Royal Dutch Shell (RDS.B) shares have gained 4.6% in the past five days, including a 1.2% gain on Tuesday to trade at 2,038.50. France's Total (TOT) is at €44.67, up 5.2% over five days including 1.6% Tuesday.

In the U.S. Exxon Mobil (XOM) climbed 1.4% Monday to close at $86.49, up just under 1% over five days. Chevron (CVX) gained just under 1% Monday, but is up 3.4% over five days, at $110.18.

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