In its most recent biennial assessment, the Potential Gas Committee said the United States possesses far more natural gas resources than previously thought. The reason can be summed up in two words: shale plays.
New drilling technologies have unlocked vast amounts of natural gas from shale formations throughout the country. The result is the largest jump in resources in the Potential Gas Committee’s 44-year history. America now has natural gas to supply the nation well into the 22nd century. And that assessment doesn’t account for future technological advances.
These shale plays are possible because of a procedure called hydraulic fracturing, or fracture stimulation. “Fracking” has been performed more than 1 million times since the 1940s without a single verified case of groundwater contamination, according to the Interstate Oil and Gas Compact Commission, which represents energy-producing states. The process has been improved upon continuously since then.
Hydraulic fracturing works like this: Several thousand feet below the earth’s surface, a mixture composed primarily of water and sand is pumped under high pressure into a shale formation containing natural gas. The mixture creates fractures in the shale. The sand keeps those fractures open, allowing natural gas to rush into the wellbore.
This process typically takes place at least a mile below groundwater sources. For instance, in the Barnett Shale of north Texas, the shale formation lies in depths ranging from 6,500 to 9,200 feet deep. By comparison, most water wells in that area are drilled to depths ranging between 150 and 700 feet. Many layers of rock separate the aquifer from the area where fracking takes place.
Devon pioneered the marriage of hydraulic fracturing and horizontal drilling in the Barnett Shale. Our success prompted the development of subsequent U.S. shale basins, including the Haynesville, the Marcellus, the Fayetteville and the Woodford. As with the Barnett, those shale formations also lie deep below the water table. None of these massive sources of natural gas could have been fully developed if not for hydraulic fracturing.