By 0838 GMT, Brent crude futures fell 27 cents, or 0.36 percent, to $75.40 a barrel, after rising 21 cents yesterday.
West Texas Intermediate crude futures fell 39 cents, or 0.54 percent, to $ 72.22, after settling unchanged in the previous session.
“Oil prices have fallen a bit as US production continues to slowly return… and while some countries are still struggling to contain the (mutated) Delta strain,” said Edward Moya, chief market analyst at OANDA.
“Oil prices are having another good week, despite the weakness in general in primary commodities caused by the strength of the dollar,” he added.
The dollar rose to a three-week high on Friday, making dollar-denominated crude oil imports more expensive for countries using other currencies.
And 28 percent of US crude production in the Gulf of Mexico was still suspended as of Thursday, two and a half weeks after Hurricane Ida.
Meanwhile, preliminary data from the US Energy Information Administration showed that US crude exports in September fell to between 2.34 and 2.62 million barrels per day from 3 million barrels per day in late August.