Definitions, Sources and Explanatory Notes

 Category:   Natural Gas Exploration & Reserves
 Topic:   Natural Gas Plant Liquids Proved Reserves

  Definitions

Key Terms Definition
Natural Gas Liquids Those hydrocarbons in natural gas which are separated from the gas through the processes of absorption, condensation, adsorption, or other methods in gas processing or cycling plants. Generally such liquids consist of propane and heavier hydrocarbons and are commonly referred to as condensate, natural gasoline, or liquefied petroleum gases. Where hydrocarbon components lighter than propane are recovered as liquids, these components are included with natural gas liquids.
Natural Gas Processing Plant A facility designed to recover natural gas liquids from a stream of natural gas which may or may not have passed through lease separators and/or field separation facilities. Another function of the facility is to control the quality of the processed natural gas stream. Cycling plants are considered natural gas processing plants.
Plant Liquids Those volumes of natural gas liquids recovered in natural gas processing plants.
Proved Reserves Proved reserves of natural gas as of December 31 of the report year are the estimated quantities which analysis of geological and engineering data demonstrate with reasonable certainty to be recoverable in future years from known reservoirs under existing economic and operating conditions.

Reservoirs are considered proved if economic producibility is supported by actual production or conclusive formation test (drill stem or wire line), or if economic producibility is supported by core analyses and/or electric or other log interpretations.

The area of a gas reservoir considered proved includes: (1) that portion delineated by drilling and defined by gas -- oil and/or gas -- water contacts, if any; and (2) the immediately adjoining portions not yet drilled, but which can be reasonably judged as economically productive on the basis of available geological and engineering data. In the absence of information on fluid contacts, the lowest known structural occurrence of hydrocarbons is considered to be the lower proved limit of the reservoir.

Volumes of natural gas placed in underground storage are not to be considered proved reserves.

For natural gas, wet after lease seperation, an appropriate reduction in the reservoir gas volume has been made to cover the removal of the liquefiable portions of the gas in lease and/or field separation facilities and the exclusion of nonhydrocarbon gases where they occur in sufficient quantity to reder the gas unmarketable.

For dry natural gas, an appropriate reduction in the gas volume has been made to cover the removal of the liquefiable portions of the gas in lease and/or field separation facilities, and in natural gas processing plants, and the exclusion of nonhydrocarbon gases where they occur in sufficient quantity to render the gas unmarketable.

It is not necessary that production, gathering, or transportation facilities be installed or operative for a reservoir to be considered proved. It is to be assumed that compression will be initiated if and when economically justified.

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

  Sources

Form EIA-23, "Annual Survey of Domestic Oil and Gas Reserves".
Form EIA-64A, "Annual Report of the Origin of Natural Gas Liquids Production"

  • Natural Gas Survey Forms and Instructions

  •   Explanatory Notes

  • Shale production volumes are broken out separately using data from LCI Energy Insight (LCI). Natural gas production from coalbed methane is also derived from LCI.
  • Related data and background information are published in the U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves Annual Report.