Gas reserves are located in areas called gas supply regions which contain one or more gas supply basins. Basins are large-scale geologic depressions, often hundreds of miles across, which contain natural gas resources. The major conventional regions supplying North America include the Gulf Coast, Permian, Fort Worth, San Juan, Rocky Mountain, Mid-Continent, Pacific Coast, Eastern, and Appalachian in the U.S. and the Western Canada and Scotian Shelf in Canada. The largest conventional producing regions currently include the Gulf Coast, Western Canada, Permian, Mid-Continent, and the Rockies. Areas that contain shale gas are commonly called shale plays. The largest shale plays that produce unconventional gas include Bakken, Barnett, Eagle Ford, Fayetteville, Haynesville-Bossler, Marcellus, Niobrara, and Utica.
The onshore Gulf Coast, Permian, Mid-Continent, Pacific Coast, and Eastern regions are more mature supply sources, meaning that much of the easy-to-find or easy-to produce gas has already been exploited. Regions with more recent development and significant undeveloped gas resources include deeper offshore Gulf of Mexico, Fort Worth, the Rockies, and the Appalachian basin. Mexico also has gas supply regions including offshore Gulf of Mexico, and various basins in eastern and northeastern Mexico. Additional significant reserves exist in northern Alaska, and the MacKenzie Delta in Canada but pipeline facilities do not currently exist to bring this gas to markets.
Numerous additional supply regions exist around the world including various countries in South America, Central Asia, the Middle East, and Africa, plus Norway, the U.K., the Netherlands, Russia, and Australia.