The Barnett Shale is a geological formation located in the Bend Arch-Fort Worth Basin. The formation underlies the city of Fort Worth and underlies 5,000 square miles.

Some experts believe the Barnett Shale may have the largest producible reserves of any onshore natural gas field in the U.S. The field is proven to have 2.5 trillion cubic feet of natural gas, and is widely estimated to contain as much as 30 trillion cubic feet of natural gas resources. Oil also has been found in lesser quantities.

The Barnett Shale is known as a "tight" gas reservoir, meaning the gas is not easily extracted. The shale is very hard, and it was virtually impossible to produce gas in commercial quantities from this formation until recent improvements were made in hydraulic fracturing technology and horizontal drilling.