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.

The plan appears to be working. Oil remains 33 percent lower than when OPEC revealed its strategy on Nov. 27, trading for $48.38 a barrel at 10:13 a.m. in London Wednesday. U.S. crude production has retreated about 500,000 barrels a day from the three-decade peak reached in June to 9.1 million a day in the week to Oct. 9, according to data from the Energy Information Administration.

Russia, Kazakhstan and Azerbaijan all have safety cushions of income from oil and gas to help in the hard times of benchmark Brent crude under $50 a barrel.

Saudi Arabia's crude oil exports fell by 278,000 barrels per day in August, despite historically high wellhead production, while volumes of shipped refined oil products rose to a record high, official data showed on Sunday.

World economic growth has been revised down to 3.1% for 2015 and to 3.4% for 2016. While OECD growth remains unchanged at 2.0% for 2015 and 2.1% in 2016, major emerging economies are increasingly facing challenges. China’s and India’s growth forecasts have been revised down by 0.1 percentage points to now stand at 6.8% and 6.4% for China and at 7.4% and 7.6% for India in 2015 and 2016, respectively.

The oil price collapse over the past 16 months has forced the world’s biggest energy companies to cut hundreds of billions of dollars in future spending to bolster their balance sheets. But Ali al-Naimi — oil minister and architect of the Saudi strategy to maintain output and keep prices low to hobble its rivals — voiced a commitment to press on with investments in exploration, production and refining.

EIA estimates that total U.S. crude oil production declined by 120,000 barrels per day (b/d) in September compared with August. Crude oil production is forecast to decrease through mid-2016 before growth resumes late in 2016. Projected U.S. crude oil production averages 9.2 million b/d in 2015 and 8.9 million b/d in 2016.

“We are not in disarray,” Mr. el-Badri said. “We see some light at the end of the tunnel.” He said he thinks oil markets will regain balance within 18 to 24 months.

OPEC expects global demand for its crude, under pressure in recent years because of rising supplies from outside the group, to rise to 30.3 million barrels per day in 2016, about 1 million bpd more than in 2015.