To help rebalance the market, OPEC sources told Reuters that the supply reduction pact could be extended if all major producers showed "effective cooperation".
For now, inventories remain bloated and supplies high, especially in the United States.
Recent price movements reflect this, with Brent and WTI trading within a $5 per barrel price range this year, in what has become the longest and most range-bound period since a price slump began in mid-2014.
"Despite the headlines, the massive inventory glut in both oil and gasoline continues to thwart any upward momentum," said Stephen Innes, senior trader at OANDA in Singapore.
In the United States, rising output has helped push up crude and fuel stocks to record highs.
In Asia, oil flows into the region remain as high as they were before the production cuts, data in Thomson Reuters Eikon shows, as exporters shield their big customers in a fight for market share.