Ministers on a panel monitoring the pact, comprising Kuwait, Venezuela and Algeria, plus Russian Federation and Oman, were meeting in Vienna after oil prices gained more than 15 percent in the past three months to trade above $56 a barrel.
"We see the market over the next six months going well above $60 for a simple reason. surprisingly good demand", Adi Imsirovic, head of oil trading at Gazprom Marketing and Trading, told the S&P Global Platts APPEC conference in Singapore.
Brent settled 58 cents, or 1 percent, lower at $58.44 a barrel after hitting $59.49, its highest since July 2015 and more than 34 percent above their 2017 low.
Crude inventories rose for a third straight week, building by 4.6 million barrels, about a million more barrels than forecast. "The information reason - a series of hurricanes and their consequences in the United States - has already exhausted itself, and other information reasons for raising oil prices are not expected now", he explained.
A surge in demand for diesel and fuel stock draws after Hurricane Harvey have also helped propel benchmark crude prices to almost $60 a barrel, levels not seen in over two years, analysts said.
The high compliance of producers in jointly curbing output as well as the news of (Turkey's response to) the referendum helped oil prices, said Tomomichi Akuta, senior economist at Mitsubishi UFJ Research and Consulting in Tokyo.
Hedge fund positioning in Brent and especially WTI is less lopsided, with net positions and ratios in both crudes well below the peaks set earlier this year.
The WTI curve has also flattened in the last couple of weeks indicating a bullish market. "OPEC and participating Non-OPEC producing countries recorded the highest conformity ever with their voluntary adjustments in production, achieving a level of 116%" in August, OPEC said in a statement.
Non-OPEC oil producers such as Azerbaijan, Bahrain, Brunei, Equatorial Guinea, Kazakhstan, Malaysia, Mexico, Oman, Russia, Sudan, and South Sudan agreed to reduce output by 558,000 barrels per day starting from January 1, 2017. But he noted demand for US crude appeared to be lower, partly as a result of the aftereffects of Hurricane Harvey. Which in general corresponds to the policy of the United States, which under Trump's rule intend to support its shale companies, and for this objective there is nothing better than rising oil prices.
The wellhead was uncapped, and oil gushed higher overnight with Brent rising almost four percent and WTI three percent.