A Drilling Rig Near Downtown Fort Worth

A drilling rig near downtown Fort Worth
Wet Natural Gas Proved Reserves by Area, 2009
map of Wet Natural Gas Proved Reserves by Area, 2009
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Source: U.S. Energy Information Administration, U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2009 Annual Report

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Did You Know?

In 1821, William Hart dug the first well specifically to produce natural gas in the United States in the Village of Fredonia on the banks of Canadaway Creek in Chautauqua County, New York. It was 27 feet deep, excavated with shovels by hand, and its gas pipeline was hollowed-out logs sealed with tar and rags.

Underground Reservoirs Hold Oil and Gas

A "reservoir" is a place where large volumes of methane, the major component of natural gas, can be trapped in the subsurface of the Earth at places where the right geological conditions occurred at the right times. Reservoirs are made up of porous and permeable rocks that can hold significant amounts of oil and gas within their pore spaces.

What Are Proved Reserves?

Proved reserves of natural gas are estimated quantities that analyses of geological and engineering data have demonstrated to be economically recoverable in future years from known reservoirs.

Proved reserves are added each year with successful exploratory wells and as more is learned about fields where current wells are producing. For this reason those reserves constantly change and should not be considered a finite amount of resources available. Application of new technologies can convert categories of previously uneconomic natural gas resources into proved reserves. U.S. proved reserves of natural gas have increased in every year since 1999, a trend accelerated by shale gas drilling.

How Much Natural Gas Reserves Are in the United States?

U.S. natural gas proved reserves, estimated as "wet" gas which includes natural gas plant liquids, increased by 11% in 2009 to 284 trillion cubic feet (Tcf), the highest level since 1971. Major improvements in shale gas exploration and production technologies drove the increase in U.S. natural gas proved reserves.

What Are Undiscovered Technically Recoverable Resources?

In addition to proved natural gas reserves, there are large volumes of natural gas classified as undiscovered technically recoverable resources. Undiscovered technically recoverable resources are expected to exist because the geologic settings are favorable despite the relative uncertainty of their specific location. Undiscovered technically recoverable resources are also assumed to be producible over some time period using existing recovery technology.

According to the EIA Annual Energy Outlook 2011, the United States possesses 2,543 trillion cubic feet (Tcf) of potential natural gas resources. Natural gas from shale resources, considered uneconomical just a few years ago, accounts for 862 Tcf of this resource estimate. At the 2010 rate of U.S. consumption (about 24.1 Tcf per year), 2,543 Tcf of natural gas is enough to supply over 100 years of use.