U.S. shale oil output is set to surge over the next five years stealing market share from OPEC producers and moving the country, once the world's top oil importer, closer to self-sufficiency, the International Energy Agency (IEA) said March 5.

A landmark deal in 2017 between OPEC and rivals including Russia to curb output to reduce global oversupply materially improved the outlook for other producers as prices rose sharply throughout the year, the IEA said in Oil 2018, an annual report looking at the next five years.

With U.S. supply surging, OPEC will see demand for its crude falling below current production in 2019 and 2020, the report forecast, suggesting a return to oversupply if OPEC output keeps steady.

U.S. oil output has resumed sharp growth over the past year and is expected to rise by 2.7 million barrels per day (bbl/d) to 12.1 million bbl/d by 2023, as growth from shale fields more than offsets declines in conventional supply.

"The United States is set to put its stamp on global oil markets for the next five years," said Fatih Birol, the IEA's executive director, in a statement.

Natural gas liquids will add another 1 million bbl/d to U.S. supply to reach 4.7 million bbl/d by 2023.

With total U.S. liquids production set to reach nearly 17 million bbl/d in 2023, up from 13.2 million in 2017, the United States will be by far the world's top oil liquids producer.

Oil production growth from the U.S., Brazil, Canada and Norway will more than meet global oil demand growth through 2020, the IEA said, adding that more investment would be needed to boost output after that.

Non-OPEC production is set to rise by 5.2 million bbl/d by 2023 to 63.3 million bbl/d with the U.S. alone accounting for nearly 60% of global supply growth.

Growth will be led by the Permian Basin in Texas and New Mexico, where output is expected to double by 2023.

"Despite talk of capital discipline and increased focus on returns rather than growth, U.S. producers regrouped quickly when oil prices stabilized and began to rise," the IEA said.

Production in 2017 rose by 670,000 bbl/d as drillers added 200 rigs "beating all expectations", the IEA said.

Last year, the IEA forecast U.S. shale production to grow by 1.4 million bbl/d by 2022 with oil prices of up to $60/bbl and by up to 3 million bbl with oil at $80/bbl.

OPEC Struggles

By contrast, output from OPEC producers will grow at a much slower pace, the IEA said, adding it expected Venezuelan production declines to accelerate offsetting gains in Iraq.

As a result, OPEC's crude oil capacity will grow by just 750,000 bbl/d by 2023.

With shale and other non-OPEC supply rising, demand for OPEC crude plus withdrawals from inventories will average 31.8 million bbl/d in 2019, the IEA said, 1.8 million bbl/d less than its last medium-term forecast.

This is lower than demand of 32.3 million bbl/d expected in 2018 and below the IEA's latest estimate of OPEC's production of 32.16 million bbl/d.

Demand for OPEC crude will remain below current output in 2020 at 32 million bbl/d, only rising above it in 2021 when the call on OPEC will increase to 32.6 million bbl/d, the IEA said.

With forecast capacity of 36.31 million bbl/d, OPEC will be supplying less than 35% of global demand by 2023 compared to its usual share of around 40%.

Boosted by economic growth in Asia and a resurgent U.S. petrochemicals industry, global oil demand will increase by 6.9 million bbl/d by 2023 to 104.7 million, according to the IEA.

That means demand growth of around 1.1% per year on average.

Despite steep non-OPEC oil production gains, the IEA warned that a decline in mature fields meant more investment was needed across the globe after 2020.

"Upstream investment shows little sign of recovering from its plunge in 2015-2016, which raises concerns about whether adequate supply will be available to offset natural field declines and meet robust demand growth after 2020," it said.