Shale-gas production now accounts for approximately 7% of annual domestic production, noted John Curtis, a professor at Colorado School of Mines, in a presentation at the recent AAPG annual convention in Denver.

The U.S. Energy Information Administration estimates that shale-gas production will overtake coalbed-methane production by 2025, and will grow from current volumes of more than 1 trillion cubic feet (Tcf) to 2.3 Tcf annually by 2030.

A good part of today’s shale-gas production flows from the Barnett play in North Texas. Indeed, U.S. gas production as a whole grew 9% from first-quarter 2007 to first-quarter 2008, in large part driven by the Barnett.

Various forecasts call for shale-gas supply to grow to 10% or more of daily U.S. production. Some experts have even pegged shale-gas contributions at levels as high as 50%. Among the many constraints are environmental and regulatory issues and pipeline capacities.

But one factor that does not appear to limit future supply is the sheer size of the technically recoverable resource.

The industry’s understanding of the shale-gas resource base has grown tremendously in the past few years. From older plays such as the Ohio shale in Appalachia to the Antrim in Michigan, the shale-gas universe now encompasses such powerhouses as the Barnett, Fayetteville and Woodford shales in the Midcontinent.

Today, the Haynesville, in East Texas and North Louisiana, and the burgeoning Marcellus, in New York, Pennsylvania and West Virginia, are delivering on their great promise. And, plays like the Eagle Ford in South Texas continue to emerge.

“The good news is that the technically recoverable resource base is sufficient to support increases from the 10% level on up,” said Curtis.

Curtis, based in Golden, Colorado, directs the Potential Gas Agency, the organization that provides guidance and technical support to the volunteer geoscientists comprising the Potential Gas Committee. The PGC’s year-end 2008 report estimated that U.S. potential natural gas resources have surged by 35%, largely due to huge new supplies of shale gas.

Highlights of the report include an increase in potential resources that is the largest in the PGC’s 44-year history. Estimated gas resources rose to 1,836 Tcf in 2008 from 1,321 Tcf in 2006 when the last report was issued.

When added to the Department of Energy’s proved gas reserves of 238 Tcf as of year-end 2007, the nation contains total available future supply of 2,074 Tcf, an increase of 542 Tcf over the previous evaluation.

Upon hearing these higher numbers, America’s Natural Gas Alliance chairman David Trice said, “This is just the latest in a string of authoritative reports confirming the abundance of natural gas in America.”

T. Boone Pickens, founder of the pro-gas Pickens Plan, also lauded the report’s findings. Pickens said, “There’s plenty of natural gas in the U.S. Now more than ever we need to take action to enact energy reform that will immediately reduce oil imports.”

Finally, according to The New York Times: “The finding raises the possibility that natural gas could emerge as a critical transition fuel that could help to battle global warming.”