Natural Gas

SIEC section 3 (not further disaggregated into divisions, groups or classes below the section level). One of the ten top-level sections of the Standard International Energy Product Classification (SIEC); see that page for the classification’s scope rules, coding system and full Table 3.1 code list.

3 / 30 / 300 / 3000 Natural gas

A mixture of gaseous hydrocarbons, primarily methane, but generally also including ethane, propane and higher hydrocarbons in much smaller amounts, and some non-combustible gases such as nitrogen and carbon dioxide [IRES, Ch. III, SIEC 3000, PDF p. 44, 2018].

Remark: Most natural gas is separated from both non-associated gas, originating from fields producing hydrocarbons only in gaseous form, and associated gas, produced in association with crude oil. The separation process yields marketable natural gas by removing or reducing hydrocarbons other than methane to acceptable levels; the natural gas liquids (NGL) removed in the process are distributed separately. Natural gas also includes methane recovered from coal mines (colliery gas) or coal seams (coal seam gas) and shale gas; when distributed it may also contain methane from anaerobic fermentation or the methanation of biomass. Natural gas may be liquefied (LNG) by reducing its temperature, to simplify storage and transportation when production sites are remote from consumption centres and pipeline transportation is not economically practicable [IRES, Ch. III, SIEC 3000, PDF pp. 44–45, 2018].

Natural gas is classified separately from landfill gas even though both consist mainly of methane: the distinction rests on source and production method, landfill gas arising from anaerobic fermentation of waste rather than from underground gas fields — see SIEC Classification System for this and other physically-similar-but-distinct SIEC examples [IRES, Ch. III, para. 3.14, PDF p. 36, 2018].

Chapter VI’s reference list of data items collects associated gas/non-associated gas/colliery and coal seam gas as a production breakdown (data items 3.1.1–3.1.3), and defines extraction losses (gas flared, vented, reinjected) and natural gas storage capacity as data items in their own right — see Data Items on Energy Flows and Stocks and Production, Storage and Transmission Capacity [IRES, Ch. VI, paras 6.45–6.49, 6.62–6.66, PDF pp. 92–95, 2018].

Related

• SIEC Classification System — SIEC’s scope rules, coding system and full Table 3.1 code list, of which this section is one entry; also covers the natural gas/landfill gas distinction in more detail
• Energy Products — the general energy-product definition and SIEC scope-precision rules this classification operationalizes
• Oil Shale/Oil Sands — the preceding SIEC fuel section
• Oil — the next SIEC fuel section; natural gas liquids (NGL), removed from natural gas during processing, are classified there
• Data Items on Energy Flows and Stocks — the extraction-loss data items (flaring, venting, reinjection)
• Production, Storage and Transmission Capacity — the natural gas storage-capacity data items