Definitions, Sources and Explanatory Notes

Category:	Natural Gas Storage
Topic:	Underground Storage Capacity

Definitions

Key Terms	Definition
Aquifer Storage Field	A sub-surface facility for storing natural gas, consisting of water-bearing sands topped by an impermeable cap rock.
Depleted Reservoir Storage Field	A sub-surface natural geological reservoir, usually a depleted gas or oil field, used for storing natural gas.
Natural Gas	A gaseous mixture of hydrocarbon compounds, the primary one being methane.
Salt Dome Storage Field (Salt Cavern)	A storage facility that is a cavern hollowed out in either a salt "bed" or "dome" formation.
Storage Capacity	The present developed maximum operating capacity.
Working Gas Capacity	The volume of total natural gas storage capacity that contains natural gas available for withdrawal.

For definitions of related energy terms, refer to the EIA Energy Glossary.

Sources

	Form EIA-191M, "Monthly Underground Gas Storage Report" and Form EIA-191A, "Annual Underground Gas Storage Report" . Natural Gas Survey Forms and Instructions

Explanatory Notes

Totals may not equal sum of components because of independent rounding. Geographic coverage is the 50 States and the District of Columbia. Prior to January 2013, Alaska data were not included in U.S. totals. Beginning with the January 2012 data, Form EIA-191A is no longer used as a source for natural gas storage capacity data. Capacity data are now collected from the Form EIA-191M.