Deep drilling: At Range Resources’ site in Washington County, PA, a specially designed rig is used to drill more than a thousand meters down and gradually turn 90° to follow the gas-rich shale deposit. The rig will drill half a dozen wells at the site. Beside it is a pond holding debris and mud from a well.
The first sign that there’s something unusual about the flat black rocks strewn across the shore of Lake Erie comes when Gary Lash smashes two of them together. They break easily and fall into shards that give off the faint odor of hydrocarbons, similar to the smell of kerosene. But for Lash, a geologist and professor at nearby SUNY Fredonia, smashing the rocks is a simple trick designed to catch the attention of a visitor. The black outcroppings that protrude from the nearby bluff onto the narrow beach are what really interest him.
To Lash’s expert eyes, the wide band of black shale, which runs roughly parallel to the beach, reveals hundreds of millions of years of geological history. The shale formed more than 350 million years ago when organic muck settled at the bottom of the shallow sea that covered much of what is now the eastern United States; it was once buried more than two kilometers underground but has gradually risen to the surface. Now, the exposed rock shows telltale patterns of breaks and splits. “We’ve demonstrated that these fractures could only have formed as a result of the generation of hydrocarbons,” says Lash.
This formation is the edge of vast deposits of black shale that stretch under tens of millions of acres below western New York, much of western and northern Pennsylvania, and parts of Ohio, West Virginia, Maryland, and Kentucky. The oldest and deepest layer is called the Marcellus shale, and if geologists like Lash are correct, it holds enough natural gas to help change the way the United States uses energy for decades to come.
Experts now believe that the country has far more natural gas at its disposal than anyone thought three or four years ago. The revised estimates are largely due to advanced drilling techniques that make it economically feasible to extract the fuel from shale. And while the Marcellus is the most recently discovered and possibly the largest shale-gas deposit, others are scattered throughout the country. The U.S. consumes about 23 trillion cubic feet (TCF) of natural gas a year, according to the Department of Energy’s Energy Information Agency (EIA). The Potential Gas Committee (PGC), an organization headquartered at the Colorado School of Mines, put the country’s potential natural-gas resources at 1,836 TCF in a biennial assessment released in June. That’s 39 percent higher than its estimate of two years earlier. Add to that the 238 TCF that the EIA has calculated in “proved reserves” (the gas that can be produced given existing economic conditions) and the PGC pegs the future supply at 2,074 TCF. In other words, there is enough natural gas to supply the country for 90 years at current consumption rates. Even if we used natural gas to totally replace coal in generating electricity, domestic supplies would last for 50 years.
Almost all the newfound resources are in shale deposits, which are now estimated to contain 616 TCF of recoverable gas, says John Curtis, a professor of geology and geological engineering at the Colorado School of Mines and director of the Potential Gas Agency, which provides technical assistance to the PGC. Supplies in the Appalachian basin alone are calculated at 227 TCF, with the Marcellus accounting for the bulk of that. And Curtis says he expects that even more shale gas will “be in the mix” in the committee’s next assessment.
Indeed, some geologists believe that gas supplies in the Marcellus and other shale deposits might be even more abundant than the PGC estimates. In January 2008, Lash and Terry Engelder, a colleague at Pennsylvania State University, calculated the amount of recoverable gas in the Marcellus deposit at 50 TCF. But initial drilling efforts in the region have gone so well that Engelder now puts the recoverable supply of gas at 489 TCF. If that’s correct, it makes the Marcellus the second-largest natural-gas field in the world; only a massive offshore reserve shared by Iran and Qatar is larger.
Natural gas offers advantages over other fossil fuels. It burns cleaner than coal, producing much less carbon dioxide. Since coal-fired power generation is responsible for a third of U.S. carbon dioxide emissions, replacing at least some of that coal with gas could significantly reduce such pollution. And using natural gas to replace gasoline and diesel fuel in vehicles could reduce the country’s reliance on foreign oil.