"Almost as importantly, there have been some signs that there has been some wavering in terms of demand growth."
Weekly U.S. data on crude production and inventories, plus a monthly report on supply and demand from the Organization of the Petroleum Exporting Countries, should provide a detailed picture of how quickly global crude inventories are falling.
Analysts forecast U.S. crude stocks declined for a fifth week in a row, falling 1.8 million barrels during the week ended May 5, after hitting an all-time high over 535.5 million barrels at the end of March, according to a Reuters poll.
High U.S. gasoline stocks have fed some concern about demand in the United States, where consumer spending expectations hit a three-year low last month and vehicle sales have fallen year-on-year for four months in a row.
Coupled with that is faltering manufacturing activity and a drop in commodity imports in China, the world's second-largest economy and biggest raw materials consumer.
Even though OPEC has stuck to its pledge to cut production, U.S. output has risen by more than 10 percent since mid-2016 to 9.3 million barrels per day, close to the output of Russia and Saudi Arabia.
"U.S. oil production surpassed expectations in terms of an early bottoming and swift uptick, and is set to expand further based on the latest drilling momentum," said Norbert Ruecker, head of macro and commodity research at Julius Baer.
"We see prices between $45-50 per barrel as fundamentally justified. Consequently, we have raised our view to neutral from bearish and closed our short position. An extension of the supply deal beyond June looks likely but its effectiveness will remain questioned."
On the physical markets, barrels of North Sea crude changed hands at their lowest levels since late 2015 on Monday.
— CNBC's Tom DiChristopher contributed to this report.