Analysts say oil producers will have to cut production more quickly to drain global oversupply
US oil drillers over the past month have added the most drilling rigs since 2012
Sanctions news added to volatility in what had already been a day of choppy trading
Prompts investor concern about the Opec and other producers effectiveness at supporting prices by cutting supplies
Crude inventories rose 2.3 million barrels in the week to Jan 13
While the Opec signalled a drop in the global oil supply surplus this year
Gains were also capped due to rising US production
Global oil production remains high and inventories near record levels in many areas
OPEC agreed to cut output by 1.2 million bpd to 32.5 million bpd for the first six months of 2017
Brent crude futures was trading at $55.87 per barrel on Friday
Consumption of fuels, a proxy for oil demand, surged 10.7 percent to 196.48 million tonnes in 2016
Prices for Brent crude futures were trading at $53.77 per barrel at 0130 GMT
Prices for Brent crude futures were trading at $54.99 per barrel at 0136 GMT
Iran's surging tanker exports were not the only indicator of plentiful supplies
Contracts were largely flat on the week after days of choppy trading
Analysts said that current prices were around break-even levels for many producers
US bank said it expected Brent prices to peak at $59 a barrel by mid-2017
Global benchmark Brent crude futures were up 49 cents at $55.96 a barrel by 0924 GMT
Despite Wednesday's dip in the dollar, analysts expect the greenback to remain strong in the near future
Prices fall due to strong dollar, which rallied to its highest since 2002