An aerial view of Phillips 66 oil refinery in the United States.

Oil prices ended higher on Friday, boosted by signals from Saudi Arabia that OPEC could cut output, but trading was volatile as investors digested and ultimately shrugged off warnings from the head of the U.S. Federal Reserve about economic pain ahead.

Brent crude futures rose $1.65 to settle at $100.99 a barrel. U.S. West Texas Intermediate (WTI) crude futures rose 54 cents to settle at $93.06 a barrel. Both contracts rose and fell by $1 throughout the session.