HOUSTON (Reuters) - U.S. oil producers could expand daily output by 1 million barrels next year, or by as little as 100,000 barrels, with the wide gap creating huge uncertainty as OPEC officials gather this week to weigh production curbs.

FILE PHOTO: Chevron oil exploration drilling site near Midland, Texas, U.S. August 22, 2019. Picture taken August 22, 2019. REUTERS/Jessica Lutz/File Photo

Shale output has routinely defied naysayers over the past three years as U.S. production has surged to nearly 13 million barrels per day (bpd), making the nation the world’s largest crude oil producer and a major exporter with an average of just under 3 million bpd so far this year.

But the outlook for 2020 comes with growing skepticism from those inside the industry - and should growth fall short, it could shift the balance of power in world supply back to the Organization of the Petroleum Exporting Countries.

An increase in U.S. crude output by 1 million bpd would satisfy nearly all of the 1.2 million bpd increase in world demand next year, the International Energy Agency expects. [IEA/M]

That would keep a lid on prices, pressure OPEC to extend production cuts and leave shale producers still trying to achieve elusive profits. As a result, most industry executives and consultants said they expect slower U.S. shale growth.

OPEC and its allies, which have cut output by 1.2 million bpd, meet in Vienna on Dec. 5-6 to weigh their next steps. The current supply cuts now run through to March.

“I don't think OPEC has to worry that much more about U.S. shale growth long term,” Pioneer Natural Resources PXD.N Chief Executive Scott Sheffield said last month, noting oil majors are the last companies aggressively drilling in the Permian Basin, the top U.S. shale field.

Producers have reduced the number of oil rigs operating for a record 12th month in a row, sidelining a quarter of the country’s drilling rigs in the past year, according to service firm Baker Hughes.

Shale producers such as Pioneer, Range Resources RRC.N, EQT Corp EQT.N, and Whiting Petroleum WLL.N have reduced production targets and cut staff, aiming to meet investor demands for higher returns and debt reduction.

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“This was a hard decision to make and one we did not take lightly, but ultimately it was a necessary, prudent action,” Range Resources CEO Jeff Ventura told Reuters of his firm’s actions.

The company has sold $1.1 billion in assets, closed offices and reduced staff, using proceeds to buy back shares and reduce debt amid weaker oil prices.

NO LONGER A COTTAGE INDUSTRY

The cuts, however, have only slowed U.S. crude production gains, not halted them. Output gains by larger oil companies and a lag effect from smaller companies’ reductions have wildly varying 2020 output forecasts.

U.S. oil production next year will rise 1 million bpd, U.S. Energy Information Administration predicted, with shale accounting for most of that.

Energy researchers IHS Markit and Wood Mackenzie separately put gains at 440,000 to 450,000 bpd while Goldman Sachs Group estimated a gain of 600,000 bpd.

Global inventories are “a little bit oversupplied,” said Ian Nieboer, an analyst with researcher RS Energy Group, which puts U.S. growth at about 100,000 bpd next year. “It puts a lid on any optimism.”

Oil majors Exxon Mobil Corp XOM.N and Chevron Corp CVX.N have not pulled back from their Permian plans. Exxon is targeting 1 million bpd of production by 2024 in the Permian and Chevron is aiming for 900,000 bpd a year earlier. Top Permian producer Pioneer also recently increased its forecast for this year's oil output and aims for a mid-teens percentage gain over several years.

Oil majors are less susceptible to lower prices and will continue to invest in the Permian, said Muqsit Ashraf, senior managing director for energy at Accenture Strategy, adding that the largest independents also are likely to expand output.

Increased scale will give the majors an edge in the Permian, said Chris Snyder, an oil analyst at Deutsche Bank.

“Historically shale was a cottage industry, with one well drilled at a time and each done differently,” said Snyder. “As we move to this manufacturing approach, that favors the skill sets of majors. They’re excellent project managers,” he said.

“The debate right now in the U.S. market is ‘does growth matter anymore?’ Clearly (producers) are favoring cash production and generation over growth,” said Snyder, alluding to the thousands of wells that have been drilled but not completed and hooked up to pipelines.