Other producers acknowledge they are concerned about supply outstripping demand. EOG’s Mr. Papa said that if recent discoveries prove as successful as companies expect, the industry will need to promote natural gas for both power generation and transportation.

“It’s going to change the dynamics of the gas markets,” Mr. Papa said.

The new supplies could pose problems for importers of liquefied natural gas. U.S. LNG imports are down two-thirds from last year because higher prices in Asia and Europe have attracted shipments to those markets. If new U.S. production keeps prices comparatively low, LNG imports are unlikely to rise.

The U.S. natural-gas industry has a history of booms and busts. Last fall, producers cut back production when predictions of a warm winter drove prices to below $6 per million BTUs.

But experts say the current situation is different. Instead of a single big discovery or a weather-related demand slump leading to a temporary rise in supplies, the industry has found a completely new resource — shale — that could last decades.

Shale — or dense rock formations that are common in many parts of the country and around the world — has long been known to hold natural gas. But production was impractical because the rock isn’t porous enough for the gas to flow.

In the 1990s, however, companies figured out how to crack the shale using pressurized water, releasing the gas. They perfected the technique in the Barnett Shale, a massive shale-gas field around Fort Worth, Texas, that now produces about four billion cubic feet per day of natural gas, 6.5% of total U.S. production and quadruple what it produced in 2004.

The success of the Barnett set off a frantic search for new shale fields, some of them staggeringly large. The recently discovered Haynesville Shale in northwest Louisiana and East Texas has by some estimates 250 trillion cubic feet of recoverable gas, five times as much gas as the Barnett. The massive Marcellus Shale formation in Appalachia could be bigger still. Together, U.S. shale plays could hold as much as 840 trillion cubic feet of gas by one industry estimate — the equivalent of more than 140 billion barrels of oil, more than half the proven reserves of Saudi Arabia.

It is still early, and the actual amounts produced could be lower. Nor will all that gas be available right away. Producing it will require drilling tens of thousands of wells at a cost of billions of dollars. Limited availability of drilling rigs, oil-field workers and pipeline capacity, as well as environmental and regulatory constraints, will restrict how fast production can grow.

But the recent discoveries have put natural-gas producers in a fundamentally different position from their oil-producing peers. Many gas producers are promising double-digit production growth next year. Meanwhile, Chevron Corp. saw production decline 3.4%, and Exxon’s oil production fell 2% in the second quarter from a year earlier, excluding unusual disruptions.

“There’s very little doubt that you can bring this much gas supply on. The reserves are there,” Credit-Suisse analyst Jon Wolff said. “The issue is, does that amount of gas push the price down?”