Is motherlode down there?

Geologists have confirmed the presence of very large deposits of natural gas deep underground in northcentral Pennsylvania.

The gas is contained 6,000 to 7,000 feet down in a geological formation called the Marcellus Shale, which extends all the way from Tennessee northward into New York State.

New exploration techniques, called horizontal drilling, can now recover gas deposits that were unrecoverable a short time ago.

State University of New York professor Gary Lash and his partner, Penn State professor Terry Engelder, say a gas boom could be imminent.

"The U.S. Geological Survey has predicted two trillion cubic feet of natural gas in this Marcellus deposit," Lash said. "Our estimates are perhaps as high as 500 trillion cubic feet."

Lash explained that the gas is trapped in microscopic spaces in rock formations. After drilling straight down to a certain depth, the drill is turned sideways in order to drill perpendicular to naturally occurring vertical fractures in the rock.

"Then," said Lash, "what they do is they pump fluids down into the well to pressurize the rocks, causing them to crack, and that allows the gas to migrate upward through a complex piping system."

It takes from 660,000 to one million gallons of water for each well.

Engelder and Lash have spent 30 years and an estimated $3 million on research.

Pennsylvania alone counts an estimated 35,000 to 40,000 active gas wells and is adding about 4,000 a year. Most of those wells tap gas that sits 2,000 to 3,000 feet below the surface.

Once the deeper wells are drilled and running, drawing the available gas from the Marcellus Shale is likely to last more than a decade.