Definitions, Sources and Explanatory Notes

 Category:   Natural Gas Production
 Topic:   Gross Withdrawals and Production

  Definitions

Key Terms Definition
Coalbed Methane Methane is generated during coal formation and is contained in the coal microstructure. Typical recovery entails pumping water out of the coal to allow the gas to escape. Methane is the principal component of natural gas. Coalbed methane can be added to natural gas pipelines without any special treatment.
Dry Natural Gas 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 Natural gas withdrawn from reservoirs is reduced by volumes used at the production (lease) site and by processing losses.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 Volumes of dry gas withdrawn from gas storage reservoirs are not considered part of production.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.
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.
Flared Gas disposed of by burning in flares usually at the production sites or at gas processing plants.
Gas Well A well completed for the production of natural gas from one or more gas zones or reservoirs. Such wells contain no completions for the production of crude oil.
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.
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.
Nonhydrocarbon Gases Typical nonhydrocarbon gases that may be present in reservoir natural gas, such as carbon dioxide, helium, hydrogen sulfide, and nitrogen.
Oil Well (Casinghead) Gas Natural gas produced along with crude oil from oil wells. It contains either dissolved or associated gas or both.
Production The volume of natural gas withdrawn from reservoirs less (1) the volume returned to such reservoirs in cycling, repressuring of oil reservoirs, and conservation operations; less (2) shrinkage resulting from the removal of lease condensate; and less (3) nonhydrocarbon gases where they occur in sufficient quantity to render the gas unmarketable. Volumes of gas withdrawn from gas storage reservoirs and native gas, which has been transferred to the storage category, are not considered production. Flared and vented gas is also considered production. (This differs from "Marketed Production" which excludes flared and vented gas.)
Repressuring The injection of gas into oil or gas reservoir formations to effect greater ultimate recovery.
Shale Gas Natural gas produced from organic (black) shale formations.
Vented Gas released into the air on the production site or at processing plants.

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

  Sources

1967-1975: Figures based on reports received from State agencies and Bureau of Mines estimates. 1976-1979: Appropriate State agencies' responses to informal data requests and the United state Geological Survey (USGS). 1980-1981: Form EIA-627, "Annual Quantity and Value of Natural Gas Report," and the USGS. 1982-1995: Form EIA-627, "Annual Quantity and Value of Natural Gas Report," and the United State Minerals Management Service; West Virginia, 1995 and 2000: EIA, U.S. Crude Oil, natural Gas, and Natural Gas Liquids Reserves, Annual Report, and EIA computations. 1996-2006: Form EIA-895M, "Monthly Quantity and Value of Natural Gas Production Report" . 2007-2010: Form EIA-895A, "Annual Quantity and Value of Natural Gas Production Report" , Form EIA-914, "Monthly Natural Gas Production Report" , Form EIA-816, "Monthly Natural Gas Liquids Report" , Form EIA-64A, "Annual Report of the Origin of Natural Gas Liquids Production" , the U.S Bureau of Ocean Energy Management, Regulation, and Enforcement (formerly the U.S. Mineral Management Service), HPDI, BENTEK Energy LLC and industry reports. Gross withdrawals data by state for 2011-forward were obtained directly from the states. Gross production data from shale and coalbed methane were obtained from LCI.

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

  •   Explanatory Notes

  • Monthly preliminary (from January 2011 to present) state-level data for the production series, except marketed production, are not available until after the final annual reports for these series are collected and processed. Final annual data are generally available in the third quarter of the following year.
  • For 1967 through 1970, Arizona, Florida, Missouri, and Tennessee are included in Alabama's volumes. Beginning with monthly data for January 2006, "Other States" volumes include all of the natural gas producing states except: Alaska, Louisiana, New Mexico, Oklahoma, Texas, Wyoming, and the Gulf of Mexico. "Other States" volumes prior to January 2006 include: Arkansas, Illinois, Kentucky, Maryland, Missouri, Nebraska, Nevada, New York, Ohio, Pennsylvania, South Dakota, Tennessee, Virginia, and West Virginia. Data for 2008 to the current month are estimated. Federal Offshore Gulf of Mexico production volumes are presented as a separate data series beginning in 2001. For Alabama, Louisiana and Texas all data through 2000 include Federal Offshore production.
  • Nonhydrocarbon gases removed increased significantly in 1996 due to production increases in the Bravo Dome.
  • Beginning with 1965 data, all volumes are shown on a pressure base of 14.73 psia at 60 degres Fahrenheit. For prior years, the pressure base is 14.65 psia at 60 degrees Fahrenheit.
  • Form EIA-895, “Annual Quantity and Value of Natural Gas Production Report”, for years prior to 2007, coalbed and shale production data are included in gas well totals. Coalbed and shale production volumes are broken out separately for 2007 forward using data from LCI. Producing reservoirs may not be consistently classified in some areas; different interpretations of how to classify shale and non-shale formations are possible.
    Nonhydrocarbon Gases Removed
  • Annual data on nonhydrocarbon gases removed from marketed production-carbon dioxide, helium, hydrogen sulfide, and nitrogen are reported by state agencies on the voluntary Form EIA-895A through 2010. For 2011 forward, data were obtained directly from the states.
  • Beginning with report year 1990, states filing the Form EIA-627, "Annual Quantity and Value of Natural Gas Report," were asked to supply monthly breakdowns of all data previously reported on an annual basis. The sums of the reported figures were used to calculate monthly volumes. In 1997, the Form EIA-627 was discontinued. States were requested to file an annual schedule on the monthly Form EIA-895. In 2011, monthly production data by state were obtained directly from the states, with the exception of Pennsylvania, where it was only available bi-annually. For Pennsylvania, quarterly shale data from LCI was used to estimate a monthly pattern for gross production obtained from the state.
    Marketed Production
  • Through 2010, natural gas production annual data were collected from 33 gas-producing states on Form EIA-895A which included gross withdrawals, vented and flared, repressuring, nonhydrocarbon gases removed, fuel used on leases, marketed production (wet), and extraction loss. In 2011 forward, the same data were obtained directly from the states. In instances where vented and flared, repressuring, nonhydrocarbon gases removed and fuel used on leases data were unavailable, EIA estimated these quantities by using the historic ratio of gross production to these items from previous years for each state. The U.S. Bureau of Safety and Environmental Enforcement also supplies data on the quantity and value of natural gas production on the Gulf of Mexico and Outer Continental Shelf.
  • Average wellhead prices through 2010 were calculated from volumes and values reported in Part IV of the Form EIA-895A. These data are shown as "Reported Wellhead Value." From January 2011 forward, monthly and annual wellhead prices are estimated according to the methodology described in Appendix A of the Natural Gas Monthly.
  • In many states, the marketed production volumes are larger than the reported wellhead value volumes. Differences in these volumes generally result from differences in definition and reporting requirements for separate data systems in the state. For example, while production quantities of federal, tribal, and state royalty gas are included in marketed production, some state reporting rules exclude these quantities from reported wellhead value volumes.
  • All monthly data are considered preliminary until after publication of the Natural Gas Annual for the year in which the report month falls. Preliminary monthly data are published from reports from the Form EIA-914, "Monthly Natural Gas Production Report". Volumetric data are converted, as necessary, to a standard 14.73 psia pressure base.
  • Final monthly data are the sums of monthly data reported on the Form EIA-895A annual schedule.
    Natural Gas Processed and Extraction Loss
  • Annual data on nonhydrocarbon gases removed from marketed production–carbon dioxide, helium, hydrogen sulfide, and nitrogen– were reported by state agencies on the voluntary Form EIA-895A through 2010 and were obtained directly from the states or estimated by EIA for 2011-forward.
  • Extraction loss is the reduction in the volume of natural gas available for disposition resulting from the removal of natural gas liquid constituents at natural gas processing plants. It represents that portion of the "raw" gas stream that is transferred from the natural gas supply chain to the petroleum and natural gas liquids supply chain. Extraction loss does not include the reduction in volume resulting from the removal of nonhydrocarbon constituents or gas used as fuel, vented, flared, or otherwise disposed of within natural gas processing plants. Extraction loss also results in a reduction in the total heat (Btu) content of the natural gas stream equal to the heat content of the liquids extracted.
  • The Form EIA-64A, "Annual Report of the Origin of Natural Gas Liquids Production," collects data on the volume of natural gas received for processing, the total quantity of natural gas liquids produced, and the resulting shrinkage (defined as extraction loss in this report) from all natural gas processing- and cycling-plant operators. The quantity of natural gas received and liquids produced are reported by state of origin of the natural gas. Shrinkage volumes are calculated and reported by plant operators based upon the chemical composition of the liquids extracted using standard conversion factors specified in the form instructions
  • To estimate the quantities of individual products extracted in each state, data from the Form EIA-64A survey were used to determine the total liquids production, and data from the Form EIA-816, "Monthly Natural Gas Liquids Report," survey were used to estimate the quantities of the individual products contained in those total liquids.
  • The Form EIA-816 captures information on the quantity of individual components (i.e., ethane, propane, normal butane, isobutane, and pentanes plus) produced or contained in mixes of plant liquids as determined by chemical analysis. The volumetric ratios of the individual components to the total liquids, as calculated from the 12 monthly Form EIA-816 reports for each state, were applied to the annual total liquids production, as reported on the Form EIA-64A, to estimate the quantities of individual components removed at gas-processing plants.
  • The heat (Btu) content of liquids extracted is not reported on the Form EIA-64A. Therefore, in order to estimate the extraction loss heat content, data reported on the Form EIA-816 were used to determine the individual products contained in the total liquids reported on Form EIA-64A.
  • The heat (Btu) content of extracted liquids was estimated by applying conversion factors to the estimated quantities of products extracted in each state. These conversion factors, in million Btu per barrel of liquid produced, were ethane, 3.082; propane, 3.836; normal butane, 4.326; isobutane,3.974; and pentane plus, 4.620. It should be noted that, at the state level, extraction losses are not necessarily related to state production.
  • Extraction loss annual data are calculated from filings of Form EIA-64A.
  • Preliminary extraction loss data are derived from data reported on Form EIA-816.
  • Extraction loss volumes for Gulf of Mexico Federal production are included in the total extraction loss volumes for the States of Alabama, Louisiana, and Texas.
  • Monthly data are revised after the publication of the Natural Gas Annual. Final monthly data are estimated by allocating annual extraction loss data to each month based on its total natural gas marketed production.