Definitions, Sources and Explanatory Notes

 Category:   Natural Gas Summary
 Topic:   U.S. Monthly Supply & Disposition

  Definitions

Key Terms Definition
Balancing Item Represents the difference between the sum of the components of natural gas supply and the sum of the components of natural gas disposition. These differences maybe due to quantities lost or to the effects of data reporting problems. Reporting problems include differences due to the net result of conversions of flow data metered at varying temperature and pressure bases and converted to a standard temperature and pressure base; the effect of variations in company accounting and billing practices; differences between billing cycle and calendar period time frames; and imbalances resulting from the merger of data reporting systems which vary in scope, format, definitions, and type of respondents.
Consumption The use of natural gas as a source of heat or power or as a raw material input to a manufacturing process.
Dry Production The process of producing consumer-grade natural gas. Natural gas withdrawn from reservoirs is reduced by volumes used at the production (lease) site and by processing losses. Volumes used at the production site include (1) the volume returned to reservoirs in cycling, repressuring of oil reservoirs, and conservation operations; and (2) gas vented and flared. Processing losses include (1) nonhydrocarbon gases (e.g., water vapor, carbon dioxide, helium, hydrogen sulfide, and nitrogen) removed from the gas stream; and (2) gas converted to liquid form, such as lease condensate and plant liquids. Volumes of dry gas withdrawn from gas storage reservoirs are not considered part of production. Dry natural gas production equals marketed production less extraction loss.
Exports Natural Gas deliveries out of the Continental United States and Alaska to foreign countries.
Extraction Loss The reduction in volume of natural gas due to the removal of natural gas liquid constituents such as ethane, propane, and butane at natural gas processing plants.
Gross Withdrawals Full well-stream volume, including all natural gas plant liquids and all nonhydrocarbon gases, but excluding lease condensate. Also includes amounts delivered as royalty payments or consumed in field operations.
Imports Natural Gas received in the Continental United States (including Alaska) from a foreign country.
Marketed Production Gross withdrawals less gas used for repressuring, quantities vented and flared, and nonhydrocarbon gases removed in treating or processing operations. Includes all quantities of gas used in field and processing plant operations.
Net Imports The amount by which imports exceed exports.
Net Storage Withdrawals The amount by which storage withdrawals exceed storage additions.
Storage Additions Volumes of gas injected or otherwise added to underground natural gas reservoirs or liquefied natural gas storage.
Storage Withdrawals Total volume of gas withdrawn from underground storage or from liquefied natural gas storage over a specified amount of time.
Supplemental Gaseous Fuels Supplies Synthetic natural gas, propane-air, coke oven gas, refinery gas, biomass gas, air injected for Btu stabilization, and manufactured gas commingled and distributed with natural gas.

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

  Sources

Dry Production: Form EIA-895, "Monthly and Annual Quantity and Value of Natural Gas Production Report" .   Supplemental Gaseous Fuel Supplies: Form EIA-176, "Annual Report of Natural and Supplemental Gas Supply and Disposition" .   Net Imports: 1994 and earlier years: EIA, Form FPC-14, "Annual Report for Importers and Exporters of Natural Gas." 1995 to current: "Quarterly Natural Gas Import and Export Sales and Price Report" , and EIA estimates of dry natural gas imports. Net Storage Withdrawals: 1979 and prior data from the American Gas Association, Committee on Underground Storage, The Storage of Gas in the United States and Canada. 1980 to current data from Form EIA-191, "Monthly Underground Gas Storage Report" .   Consumption: 1973-1975: Bureau of Mines, Minerals Yearbook, "Natural Gas" chapter. 1976-1978: EIA, Energy Data Reports, Natural Gas Annual. 1979: EIA, Natural Gas Production and Consumption, 1979. 1980-1989: Form EIA-176, "Annual Report of Natural and Supplemental Gas Supply and Disposition" and Form EIA-759, "Monthly Power Plant Report" . 1990: Form EIA-176, "Annual Report of Natural and Supplemental Gas Supply and Disposition" ,Form EIA-759, "Monthly Power Plant Report" and Form EIA-64A, "Annual Report of the Origin of Natural Gas Liquids Production" . 1991-1995: Form EIA-176, "Annual Report of Natural and Supplemental Gas Supply and Disposition" ,Form EIA-759, "Monthly Power Plant Report" Form EIA-64A, "Annual Report of the Origin of Natural Gas Liquids Production" and EIA-627, "Annual Quantity and Value of Natural Gas Report." 1996-2000: Form EIA-895, "Monthly and Annual Quantity and Value of Natural Gas Production Report" ,Form EIA-857, "Monthly Report of Natural Gas Purchases and Deliveries to Consumers"; Form EIA-910, "Monthly Natural Gas Marketer Survey." , Form EIA-759, "Monthly Power Plant Report" , EIA computations, and Natural Gas Annual 2000. 2001-current Form EIA-895, "Monthly and Annual Quantity and Value of Natural Gas Production Report" , Form EIA-857, "Monthly Report of Natural Gas Purchases and Deliveries to Consumers"; Form EIA-910, "Monthly Natural Gas Marketer Survey." and Form EIA-759, "Monthly Power Plant Report" .  

  • Background on "Natural Gas Monthly" data
  • Background on "Natural Gas Annual" data
  • Natural Gas Survey Forms and Instructions

  •   Explanatory Notes

  • Extraction loss is collected only on an annual basis. Monthly extraction loss is estimated from monthly marketed production by assuming that the preceding annual percentage remains constant for the next twelve months.
  • Dry gas production is equal to marketed production (wet) minus extraction loss.
  • Supplemental gaseous fuels data are collected only on an annual basis except for the Dakota Gasification Co. coal gasification facility which provides data each month. The ratio of annual supplemental fuels (excluding Dakota Gasification Co.) to the sum of dry gas production, net imports and net withdrawals from storage is calculated. This ratio is applied to the monthly sum of these three elements. The Dakota Gasification Co. monthly value is added to the result to produce the monthly supplemental fuels estimate.
  • Total consumption consists of pipeline fuel use, lease and plant fuel use, and deliveries to end-use consuming sectors.
  • Totals may not equal sum of components because of independent rounding.
    Storage
  • Net storage withdrawals data through 2006 include underground storage and liquefied natural gas storage. Data for January 2007 forward include underground storage only.
  • All monthly data concerning underground storage are published from the Form EIA-191M, "Monthly Underground Gas Storage Report." A new Form EIA-191 became effective in January 1994. Injection and withdrawal data are from the Form EIA-191M survey.
  • The final monthly and annual storage and withdrawal data include both underground and liquefied natural gas (LNG) storage. Annual data on LNG additions and withdrawals are taken from Form EIA-191M. Monthly data are estimated by computing the ratio of each month's underground storage additions and withdrawals to annual underground storage additions and withdrawals and applying it to annual LNG data.
  • There are three principal types of underground storage facilities in operation in the United States today: salt caverns (caverns hollowed out in salt "bed" or "dome" formations), depleted fields (depleted reservoirs in oil and/or gas fields), and aquifer reservoirs (water-only reservoirs conditioned to hold natural gas). A storage facility's daily deliverability or withdrawal capability is the amount of gas that can be withdrawn from it in a 24-hour period. Salt cavern storage facilities generally have high deliverability because all of the working gas in a given facility can be withdrawn in a relatively short period of time. (A typical salt cavern cycle is 10 days to deplete working gas, and 20 days to refill working gas.) By contrast, depleted field and aquifer reservoirs are designed and operated to withdraw all working gas over the course of an entire heating season (about 150 days). Further, while both traditional and salt cavern facilities can be switched from withdrawal to injection operations during the heating season, this is usually more quickly and easily done in salt cavern facilities, reflecting their greater operational flexibility.
    Imports and Exports
  • EIA reduced the reported volume of gas imported by pipeline from Canada by the amount of natural gas liquids removed from the saturated natural gas carried by Alliance Pipeline. Alliance moves saturated natural gas from the border to a processing plant in Illinois. After the adjustment, volumes of imported natural gas on this pipeline are on the same physical basis as other reported volumes of pipeline imports.
  • Prices for LNG imports are reported as “landed,” received at the terminal, or “tailgate,” after regasification at the terminal. Generally the reporting of LNG import prices varies by point of entry, and the average prices are calculated from a combination of both types of prices. The price of LNG exports to Japan is the “landed” price, defined as received at the terminal in Japan.
  • Annual and monthly data are published from the Office of Fossil Energy, U.S. Department of Energy, Natural Gas Imports and Exports.
  • Totals may not equal sum of components due to independent rounding.