Oil prices rebounded Thursday after a sharp decline the day before as traders tried to get a handle on the full implications of Iran's landmark nuclear accord.
US benchmark West Texas Intermediate for delivery in August rose 34 cents to $51.75 a barrel compared with Wednesday's close.
Brent North Sea crude for August delivery advanced 78 cents to $57.83 a barrel.
Both contracts had slid more than $1.50 on Wednesday.
Daniel Ang, an investment analyst with Phillip Futures, said the market was "still trying to grasp" the impact of the Iranian deal.
The agreement checks Iran's nuclear programme in exchange for the lifting of economic sanctions, allowing Tehran to ramp up crude exports, which have been halved by the restrictions.
Analysts have said that the return of Iranian oil to an already oversupplied global market will not be immediate, and that the earliest it could happen would be next year.