There could be a recalibration of oil market expectations regarding an “ample” global oil supply, Bahrain’s oil minister said Monday, despite expectations that U.S. shale oil production could be hurtling towards 14 million barrels per day in the next few years.

Speaking at a CNBC-moderated panel at the International Petroleum Technology Conference (IPTC) in Saudi Arabia, Bahrain’s Oil Minister Sheikh Mohammed bin Khalifa Al Khalifa said that an abundant supply of oil, currently seen amid rampant U.S. shale production, might not be so reliable as we progress through 2020.

“Going forward, all eyes are on U.S. production again, if there’s going to be an extra million barrels (of production a day), yes, this will suppress oil prices but the current indicators of rig counts … are telling you that maybe that is going to be a challenge,” he told CNBC’s Hadley Gamble, speaking on the panel in Dhahran.

“So, my recommendation is all eyes on U.S. production, if they can hit 14 million (barrels) then yes oil prices will extend a bit further but, eventually, this sentiment that there is ample supply will have to shift, there will be a scarcity impulse in supply and when that happens in the next few years, definitely, it could be as early as the end of this year, we will have to see.”

Al Khalifa cautioned that there had been few major oil discoveries recently and investment was ebbing; “So we are challenged, I think the future is challenged in terms of supply, more than people expect today.”

“We can see that investments are not as bold as they once were, then perhaps that inflection point isn’t that far away,” he added. At that point, he said the challenge would be making sure that other producers “can meet the demand that keeps rising.”

The U.S. Energy Information Administration (EIA) expects American oil production to average 13.2 million barrels a day (b/d) in 2020, an increase of 0.9 million b/d from the 2019 level. However, growth in supply is slowing from the last few years with 2018 growth of 1.6 million b/d and 2019 growth of 1.3 million b/d.

In September 2019, the U.S. exported exported 90,000 b/d more total crude oil and petroleum products than it imported, the first month recorded in U.S. data where it had exported more than it had imported. But in its latest short-term energy outlook released in January, the IEA noted that slowing crude oil production growth will result from a decline in drilling rigs over the past year and that it expected this trend to continue into 2020.

“Despite the decline in rigs, EIA forecasts (oil) production will continue to grow as rig efficiency and well-level productivity rises, offsetting the decline in the number of rigs,” it noted.

Benchmark Brent crude is trading around the $65 dollar mark while West Texas Intermediate (WTI) is trading just below the $60 per barrel level. Prices have been more or less stable since oil producer group OPEC, along with Russia and several other producers, curbed their own production to limit supply and rebalance global oil prices.

They have done this in the face of (and pressure from) massive U.S. shale oil production, however. There are concerns, especially among the OPEC+ alliance as it is now known, that efforts to stabilize prices are being hampered by growing U.S. supply and a shaky outlook for demand.

Jason Bordoff, professor and director at Columbia University’s Center on Global Energy Policy, characterized U.S. shale oil as a “new dynamic of shale in the global market — not just how much of it there is, but how short-cycle it is and how quickly it can respond to market changes,” when speaking on the same energy panel on Monday.

Saudi Arabia’s Energy Minister Prince Abdulaziz bin Salman said that while OPEC kept a close eye on U.S. shale oil inventories, he was more concerned that producers worked together so the energy market ecosystem was not undermined.

“We’re not focused on shale oil particularly. I’d hate to see our endeavor and work in OPEC being challenged by any producer, because at the end of the day we are supporting the industry and we are supporting all producers and we’re welcoming everybody, as long as they are efficient producers,” he said.

Exxon Mobil CEO Darren Woods, who was also on the panel, believed that the challenge that he saw on the supply side of the market was the ability of oil producers to produce efficiently despite volatility in the market.

“Demand will continue to grow in the decades to come because of the important role that energy and oil and gas plays in modern life … from a supply standpoint, this industry goes through lots of cycles … (one of) which is the shale revolution and the supply that came with that, so we’re going to see ups and downs,” he said.

“In the period we find ourselves today with ample supply, the challenge is to make sure you can produce this supply at the lowest cost and that you’re competitive, irrespective of where the volatility in any one year takes you. Certainly, from our perspective, that’s how we think about the business.”

“Our perspective today is that the fundamentals are strong, the demand will be there over time so we have to invest so that we’re in a position to meet that demand,” he added.