Analysts also cited continued unease about the economic effects of the US budget impasse.
US benchmark West Texas Intermediate for November delivery fell 99 cents to USD 102.02 a barrel on the New York Mercantile Exchange.
European benchmark Brent oil for November delivery declined 52 cents to USD 111.28 a barrel.
Analysts pointed to a report by the IEA, which represents energy-consuming countries, that said third-quarter growth in output from nations outside the Organisation of the Petroleum Exporting Countries (OPEC) rose by 1.7 million barrels a day compared with last year.
Besides the United States and Canada, the additional supply comes from Kazakhstan and South Sudan.
The IEA warned that the rise in non-OPEC oil would not necessarily mean lower prices because of instability in some leading OPEC countries, including Iraq and Libya.
Still, Matt Smith, analyst at Schneider Electric, said the IEA report "once again underscores the theme of booming non-OPEC supply for next year."
Analysts also continued to watch Washington as the partial government shutdown looked like it could extend into a third week.
