OPEC on Friday did not set a new oil output ceiling, with major oil producers reluctant to cut the supply.
Though OPEC maintained its production target of 30 million barrels per day, the actual oil output of the cartel has been exceeding 31.5 million barrels per day in the past months. Consequently, global oil prices have been falling, hitting a six-year low recently.
OPEC is now pumping out around 33 percent of the crude in the world, at far lower levels than the past.
The Secretary General of OPEC Abdallah Salem el-Badri said it's hard to say how much oil Tehran would add to the market in 2016, as sanctions against Iran are lifted under the deal it agreed with world major states over its nuclear plan.
OPEC added the output ceiling would be discussed in its next meeting in 2016.
Ahead of the meeting, Iranian Oil Minister Bijan Namdar Zanganeh said Iran could increase its crude output from half a million barrels per day to 1 million barrels per day once the international sanctions are lifted without any foreign investment.
The International Energy Agency (IEA) said OPEC's annual revenue may fall to 550 billion U.S. dollars from an average of more than 1 trillion U.S. dollars in the past five years.
OPEC expects further cooperation with other influential non-OPEC oil exporters such as Russia and the United States, but added there is no sign to cut global oil output.
International oil traders say rising stockpiles will continue to weigh on the oil market and prices may not rally in the next two years.
Jamie Webster, senior director at IHS Energy, told Xinhua that OPEC is not yet ready to cut the oil production. Meanwhile, oil output in the United States, a strong competitor of OPEC, could continue to decline in 2016 possibly causing oil prices to rise in the second half of that year.
