Benchmark West Texas Intermediate crude for January delivery fell 41 cents to close at US$93.68 a barrel on the New York Mercantile Exchange.
A day after assessing a deal between Iran and six world powers on the country's nuclear program, traders began looking ahead to figures on U.S. crude and gasoline stockpiles.
Data for the week ended Nov. 22 is expected to show a decline of 1.5 million barrels in crude oil stocks and an increase of one million barrels in gasoline stocks, according to a survey of analysts by Platts, the energy information arm of McGraw-Hill Cos.
Crude oil supplies rose by 400,000 barrels for the week ended Nov. 15, the ninth straight weekly increase.
Brent crude, a benchmark for international oils, slipped 12 cents to US$110.88 a barrel on the ICE exchange in London.
In other energy futures trading on Nymex, wholesale gasoline added one cent to US$2.69 a U.S. gallon (3.79 litres), heating oil added one cent to US$3.04 a gallon and natural gas gained three cents to US$3.82 per 1,000 cubic feet.
(TSX:ECA), (TSX:IMO), (TSX:SU), (TSX:HSE), (NYSE:BP), (NYSE:COP), (NYSE:XOM), (NYSE:CVX), (TSX:CNQ), (TSX:TLM), (TSX:COS), (TSX:CVE)