The U.S. shale boom, which has sent the nation’s output to a 28-year high, is curbing the impact of the Iraq crisis on the oil market, said Nansen Saleri, former head of reservoir management at Saudi Arabian Oil Co., according to Bloomberg June 19.

Prices would have climbed more this month if techniques such as hydraulic fracturing and horizontal drilling hadn’t bolstered U.S. crude output, said Saleri, who is now CEO of Houston-based consultant Quantum Reservoir Impact. WTI oil, the U.S. benchmark, has climbed $5 to $10 on supply anxiety, he said.

“Were it not for the increase in U.S. production, that’s gained close to 2 million barrels a day, we would see a $20 to $30 rise in prices,” Saleri said in a telephone interview. “The surge in U.S. production is a hugely stabilizing factor.”

WTI for July delivery rose to $107.68 a barrel (bbl) on the New York Mercantile Exchange on June 13, the highest level since Sept. 19. Prices surged 4.1% last week, the most this year, as militants of the Islamic State in Iraq and the Levant (ISIL) seized Mosul, the largest northern city, on June 10. Futures increased 46 cents, or 0.4%, to $106.43 June 19.

Brent for August settlement reached $115.71/bbl June 19 on the London-based ICE Futures Europe Exchange, the highest level since Sept. 6, and settled at $115.06. The European crude, which is used to price more than half of the world’s oil, is typically more sensitive to changes to the global supply and demand balance.

U.S. crude output rose 17,000 bbl/d to 8.477 MMbbl last week, the most since October 1986, Energy Information Administration data showed June 18. Much of the gain has come from shale formations including the Bakken in North Dakota and the Eagle Ford in Texas.

“What’s happening in the U.S. is an indication of what the rest of the industry will be doing five to 10 years from now,” he said. “If you look at North Dakota and West Texas, you’re getting a preview of what will be happening globally a decade from now.”

The rise in U.S. production has made up for the disruptions of Libyan, Iranian and now Iraqi output, Christof Ruhl, the chief economist of BP Plc (NYSE: BCS), said in New York on Bloomberg Television.

“So far nothing has happened to production,” Ruhl said. Police near the Baiji refinery, the nation’s largest, said government forces are now in control after a battle with ISIL. Crude shipments from the south, where most production is located, may accelerate next month, and Kurds are defending the Kirkuk Field in the north.

“The oil production centers of Iraq are relatively safe,” Saleri said. “There are two centers. One, responsible for about 75% of production, is in the Shia heartland of Basra province. The other 25% comes from the Kirkuk area, which is firmly under the control of the Kurds.”

Iraqi production rose 50,000 bbl/d to 3.3 MMbbl in May, according to a Bloomberg survey of oil companies, producers and analysts. Output was up 38% from the same month four years earlier, as investment poured into the country.

“Iraq has been the most promising new theater of oil production,” Saleri said.