Oil prices slumped 3% on Monday.
Oil prices fell for a third day straight on Wednesday on growing expectations that supply growth will outpace demand growth next year.
Both benchmarks posted gains of about 8% last week.
Oil prices eased on Wednesday, taking a breather after gains earlier this week.
Oil prices rose by more than $1 a barrel on Monday after top exporter Saudi Arabia raised prices for its crude sold to Asia and the United States.
Brent goes up above $70 a barrel.
The situation with oil prices has not demonstrated stability over the past 4 months.
Over the past week, world oil quotations have experienced serious volatility.