Brent crude futures fell 2.9% to settle at $82.63 on Friday, and marked the second consecutive weekly loss, down 2.8%.
A stronger dollar and concerns about China's economic outlook applied downward pressure on prices, countering the effects of tighter supply.
The dollar's value increased after unexpectedly strong U.S. labor market and manufacturing data earlier in the week, reducing demand for dollar-denominated oil from buyers using other currencies.
Additionally, recent data indicated that China's economy grew by a slower-than-expected 4.7% in Q2, intensifying worries about oil demand from the world's largest importer.
