Some central European countries continue to report declines in Russian gas deliveries, the Wall Street Journal reported on September 22, as tensions between Ukraine and Russia persist in the run-up to winter.
"I think this will be the winter of the 'Russian Bear,'" said Thomas McMahon, CEO of Singapore-based UD Trading Group and the former CEO of the Singapore Mercantile Exchange.
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Russian President Vladimir Putin may be able to make up for lost gas volumes flowing into Europe, McMahon said, because energy deals with Beijing mean "he's got China in his side pocket for revenue."
Meanwhile, OPEC producers may opt to cut supply when they meet on November 27, or may even authorize a decision earlier, if prices continue their relentless slide.
"OPEC has to be really concerned," said Carl Larry, president of Houston-based consultancy Oil Outlooks.
The average price of OPEC's basket of 12 crudes has fallen below $90 a barrel for the first time in two years.
"We believe production cuts by OPEC should allow Brent crude oil prices to stabilize and trade around $100 a barrel, with repeated spikes," said UBS strategists Giovanni Staunovo and Dominic Schnider.
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"Saudi Arabia is well-positioned to act as a 'put' against lower prices. The Kingdom holds much of the world's limited spare capacity of just 2.5-3.0 million barrels a day."
Oil prices in the last three months of this year will be "heavily dependent" on the action taken by swing producer Saudi Arabia, said Fereidun Fesharaki, chairman of energy consultancy FACTS Global Energy and a former energy adviser to the Prime Minister of Iran in the 1970s.
"So far, they have allowed oil prices to fall, and kept production flat at 9.6 million barrels a day,' Fesharaki told CNBC in an email. "We expect they will cut back production and prices will go to around $95."