The two benchmarks fell 2 percent on Monday. They are both now in the middle of $5-per-barrel trading ranges seen since early December.
"The usually fairly volatile oil price has barely budged for two months, the reason being conflicting dynamics in the market," said Hans van Cleef, senior energy economist at ABN AMRO Bank in Amsterdam.
The Organization of the Petroleum Exporting Countries and other exporters including Russia have agreed to cut output by almost 1.8 million barrels per day (bpd) during the first half of 2017 in a bid to rein in a global fuel supply overhang.
The market has largely priced in the production cuts that OPEC and other producers agreed to in November, leaving little room for prices to break out of the range, said Tariq Zahir, managing member of Tyche Capital in New York.
"It would take either a supply outage or serious cuts to move it," he said. "The first month, obviously, OPEC is going to do the best it can, but after that, let's see what the second and third month bring."
Rising production in the United States, where increased drilling activity especially by shale oil producers, has undermined these efforts. U.S. crude output is up 6.5 percent since mid-2016 to 8.98 million bpd, its highest level since April last year.
U.S. shale oil production for March is expected to rise by the most in five months to 4.87 million bpd, its highest rate of since May last year, government data showed on Monday.