Investing.com - Oil was lower Monday as U.S. drilling activity continued to pick up.
U.S. crude was off 58 cents, or 1.18%, at $48.73 at 08:00 ET. Brent crude shed 47 cents, or 0.91%, to $51.29.
Baker Hughes weekly data Friday showed a rise in the number of rigs operating in the U.S. of 14 to 631.
The was the highest number since September 2015.
U.S. oil output has risen to 9.1 million barrels a day from 8.5 million in June of last year.
Higher U.S. production reduces the impact of agreed output cuts by major producers.
OPEC and non-OPEC producers are cutting output by 1.8 million barrels a day in the first half.
Investors have cut their long futures and options positions.