If current production remains unchanged at 31.5 million barrels a day, markets will still be oversupplied by 700,000 barrels a day in 2016—though that would be less than the glut of 1.8 million a barrel a day OPEC estimates for this year.

The mistaken prognoses highlight the challenges OPEC faces on Friday when the group’s ministers gather in Vienna for a potentially contentious meeting.

Saudi Arabia, which has so far resisted any market intervention to prop up oil prices, will propose the Organization of the Petroleum Exporting Countries (OPEC) cut output by 1 million barrels per day (bpd) next year, Energy Intelligence reported.

"The council (of ministers) ... stressed the kingdom's role in (achieving) the stability of the oil market and its continuous readiness and efforts to cooperate with all OPEC and non-OPEC countries to maintain the stability of the market and prices," the cabinet said.

"To increase Iran's oil production in the global market after the lifting of sanctions, we don't need permission from OPEC (the Organization of the Petroleum Exporting Countries) or any other organization," Iran's oil minister, Bijan Zanganeh was quoted as saying by IRNA on the sidelines of the meeting of the Gas Exporting Countries Forum (GECF) in Tehran.

Canadian producers are struggling to cut the cost of extracting bitumen from the oil sands, and their other wells are failing to match the efficiency gains of U.S. rivals, a Bloomberg Intelligence analysis shows. While output keeps rising in the Permian Basin, the largest U.S. shale play, companies are slowing output from wells in Alberta and have shelved 18 oil- sands projects during the downturn, according to ARC Financial Corp.

OPEC’s board of governors was unable to agree on the group’s long-term strategy plan and won’t present it to oil ministers when they meet on Dec. 4 in Vienna, two OPEC delegates with knowledge of the matter said.

“The drop in prices won’t be a concern for us,” Zanganeh said. “It should be a concern for those who have replaced Iran.” Iran doesn’t expect difficulties selling the additional barrels, and “the market has taken into account our return,” he said.

OPEC’s share of the global oil market will expand from 2020 as prices recover to $80 and supply outside the group stagnates due to spending cuts, according to the International Energy Agency.

Internal OPEC squabbles are on the rise as members argue about the need to support a fair oil price and boost revenues just as they feel more pain from low crude prices.