Shale gas is found in many parts of the United States. These deposits occur in shale “plays” – a set of discovered, undiscovered or possible natural gas accumulations that exhibit similar geological characteristics. Shale plays are located within large-scale basins or accumulations of sedimentary rocks, often hundreds of miles across, that also may contain other oil and gas resources.

Shale gas production is, at present, occurring in 16 states. 

Natural gas is a fossil energy source that formed deep beneath the earth’s surface. Natural gas contains many different compounds. The largest component of natural gas is methane, a compound with one carbon atom and four hydrogen atoms (CH4). Natural gas also contains smaller amounts of natural gas liquids (NGL; which are also hydrocarbon gas liquids), and nonhydrocarbon gases, such as carbon dioxide and water vapor. We use natural gas as a fuel and to make materials and chemicals

Natural gas formed millions to 100’s of millions of years ago and over long periods of time when the remains of plants and animals built up in thick layers on the earth’s surface and ocean floors, sometimes mixed with sand, silt, and calcium carbonate. Over time, these layers were buried under sand, silt, and rock. Pressure and heat changed some of this carbon and hydrogen-rich material into coal, some into oil (petroleum), and some into natural gas.

In some places, natural gas leaking into the air from cracks in the earth can be ignited by lightning or a fire. When people first saw this burning natural gas, they experimented with it and learned they could use it for heat and light.

Because natural gas is colorless, odorless, and tasteless, natural gas companies add mercaptan to natural gas to give it a distinct and unpleasant odor to help detect leaks in natural gas pipelines. Mercaptan is a harmless chemical that smells like rotten eggs.

Major U.S. cities may be leaking far more methane into the atmosphere than government estimates suggest.

New measurements found that up to twice as much gas is being released from six cities on the East Coast than estimates recorded by EPA. Those cities are Washington, D.C.; Philadelphia; Boston; New York; Providence, R.I.; and Baltimore.  

Their combined methane emissions are higher than those at some of the nation’s biggest natural gas production centers, including the Four Corners region and the Bakken Shale in the Dakotas.