West Texas Intermediate futures for October delivery fell to $46.79 (-0.76%), while Brent crude slid to $48.86 (-0.45%) retreating from levels reached after the announcement of Fed's decision yesterday. Federal Reserve's policy makers voted to wait for more evidence of strength of the U.S. economy and kept interest rates unchanged. Normally low interest rates weigh on greenback and support this dollar-denominated commodity; however Fed's decision was based on economic concerns. That's why many analysts and investors remained concerned about global oil demand.

Kuwait said on Thursday that the oil market would balance itself as the time goes, signaling that OPEC intends to continue defending its market share.

Other sources said that oil prices are likely to rise by up to $5 a barrel a year and reach $80 by 2020.