NEW YORK, Nov 28 (Reuters) - The global oil market is signaling a potential shift, as traders and analysts worry about reduced crude demand and an oversupplied market in the coming months. On Dec. 5, a European Union ban on Russian crude imports is set to start, along with a plan by the G7 nations to force shippers to comply with a price cap on Russian oil sales. In the last week, crude futures contracts have flipped in and out of contango, where the prompt price of a commodity is lower than the future price, which suggests short-term weakness. Offers of Angolan and other West African crude oil to China, a main customer, are a barometer of physical crude demand from the country. In addition, European refiners have found themselves oversupplied with crude as an expected shortage owing to the looming EU ban on Russian oil has yet to materialise.

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