According to Reuters, Brent crude oil slipped because investors are growing concerned over another supply glut.
On the day, Brent crude is trading down about 31 cents, falling to $66.45 per barrel.
But the price for Brent crude futures has a few influential factors.
For one, US oil inventory is on the rise, with eight straight weeks of growth.
But US inventories are also swelling at their fastest rate in a year.