Crude oil prices fell more than 1 percent on Friday to multi-week lows as swelling Iranian exports reinforced fears of a global glut, while gasoline rallied on refinery and pipeline outages.
Falling US equity prices and a rising dollar also weighed on crude futures and other industrial commodities denominated in the greenback.
Gasoline was the only bright spot on the petroleum complex, rising more than 2 percent on news of an extended outage at one of the main units of BP's refinery in Whiting and closure of Colonial Pipeline's main gasoline line. The profit for turning crude into gasoline hit three-month highs.
Brent crude futures were down 50 cents, or 1 percent, at $46.09 a barrel by 11:24 a.m. EDT (1524 GMT). At the session low, they hit $45.48, a two-week bottom.
US West Texas Intermediate crude futures fell 70 cents, or 1.6 percent, to $43.21 a barrel. WTI hit a five-week low of $42.74 earlier.
Brent was on track to a weekly loss of 4 percent and WTI a loss of 6 percent.
"Crude futures are taking on an increasingly bearish appearance," said Jim Ritterbusch of Chicago-based oil markets consultancy Ritterbusch & Associates.
For WTI, "this can potentially expedite our expected trip south to the $39 area", he said.
The market is awaiting a weekly reading on the US oil rig count at 1:00 p.m. EDT (1700) to see if a recent trend of rising rigs continues.
Oil slumped after a source familiar with Iran's tanker loading schedules said the third-biggest OPEC producer has raised its crude exports to more than 2 million barrels per day (bpd) in August, nearing pre-sanctions levels.
There are also signs of a returning of output from Nigeria and Libya, two countries whose crude exports have been hampered in the past by conflict and unrest. US oil output has also grown more than that of any producer in recent years, data shows.
Gasoline rallied on news that BP Plc plans to shut for up to 10 days the large crude distillation unit at the 413,500 bpd refinery in Whiting, Indiana. That would add to closure of the refinery's gasoline-producing fluidic catalytic cracking unit. Gasoline has been up since the week began after Colonial Pipeline said its main gasoline line has been idled by a leak.