BP Plc Chief Executive Officer Tony Hayward said that unconventional gas will transform energy production in the U.S.

“It’s a complete game changer in the U.S., certainly” and alters the U.S. energy outlook “for probably a hundred years,” the head of Europe’s second-largest oil company said in a panel discussion in Davos, Switzerland today. “It is yet to be seen if the same can be applied globally.”

The U.S. overtook Russia as the world’s largest natural-gas producer last year as companies used new technology to tap so- called tight and shale gas trapped between hard rocks. In December, Exxon Mobil Corp. agreed to pay $30 billion for XTO Energy Inc., a shale gas producer in Texas and North Dakota.

Royal Dutch Shell Plc CEO Peter Voser said unconventional gas will have a “global impact.” Sitting on the same panel as Hayward in Davos, Voser said unconventional gas resources are “a big deal and necessary.”

The increase in U.S. output has cut demand for ship-bound liquefied natural gas imports, diverting fuel to Europe and cutting prices. OAO Gazprom, Russia’s gas export monopoly may delay its Shtokman gas export project because increased U.S. production will cut import demand, a report said this week.

Unconventional sources may boost global gas reserves rise 60 percent with potential for discoveries in North Africa, the Middle East, Europe and China, BP, Europe’s biggest oil company by market value, said in October.