Oil prices slipped on Friday, as traders took profits following a rally on plummeting Venezuelan production, strong global demand and looming U.S. sanctions on Iran.
U.S. West Texas Intermediate crude futures ended Friday's session down 21 cents at $71.28 a barrel, but posted a third straight week of gains.
Brent crude futures were down 81 cents, or 1 percent, to $78.49 a barrel by 2:29 p.m. ET, set for a sixth straight week of gains.
The international benchmark broke through $80 for the first time since November 2014 on Thursday, but gave up nearly all of the day's gains in afternoon trading. Investors anticipate more gains due to supply concerns, at least in the short-term. Brent has gained about 17 percent since the start of the year.
"Oil prices are in overbought territory, which has prompted some profit taking in today's trading session ahead of the weekend," said Abhishek Kumar, senior energy analyst at Interfax Energy's Global Gas Analytics in London.