To support the industry and stakeholders in the use of consistent terminology, Ipieca, IOGP, GIE and MARCOGAZ prepared this methane emissions glossary covering the whole natural gas value chain.

Intended for policymakers and regulators working on methane regulation in Europe, this glossary will be updated to reflect new legislation and technologies.

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There are currently 5 names in this directory beginning with the letter D.

Detection threshold
The minimum quantity or concentration of a gas (e.g. methane) which is reliably detectable by detection equipment. This is sometimes called a minimum detection limit (MDL). [8]

Equipment (active or passive) related to the physical gas system and needed in order to keep the normal operation of the network. [12] (Note - Please see definition of Granularity terms below)

Directed Inspection and Maintenance (DI&M)
Programme to confirm that equipment (e.g. pneumatic devices) are operating per design and emissions remain within specified ranges. (Note - DI&M can be a complement to LDAR programmes)

Supply of gas through local or regional pipeline networks to its customers, usually ending with the customer meter, and so excluding end-use.

Distribution System Operator (DSO)
A natural or legal person who carries out the function of distribution and is responsible for operating, ensuring the maintenance of, and, if necessary, developing the distribution system in a given area and, where applicable, its interconnections with other systems, and for ensuring the long-term ability of the system to meet reasonable demands for the distribution of gas. [1]


[1] Directive 2009/73/EC of the European Parliament and of the Council of 13 July 2009

[2] EN-12186 – Gas infrastructure – Gas pressure regulating stations for transmission and distribution – Functional requirements

[3] EN-12327 – Gas infrastructure – Pressure testing, commissioning and decommissioning procedures – Functional requirements

[4] EN-12583 – Gas Infrastructure – Compressor stations – Functional requirements

[5] EN-15446 – Fugitive and diffuse emissions of common concern to industry sectors – Measurement of fugitive emission of vapours generating equipment and piping leaks

[6] GIE & MARCOGAZ Report “Potential ways the gas industry can contribute to the reduction of methane emissions”

[7] IPIECA/API/IOGP (2020). Oil and gas industry guidance on voluntary sustainability reporting

[8] IPIECA Methane Glossary

[9] ISO 14532 – Natural gas — Vocabulary

[10] JCGM-100 – Evaluation of measurement data – Guide to the expression of uncertainty in measurement. s.l.: Committee for Guides in Metrology (JCGM/WG 1), 2008

[11] MARCOGAZ – Assessment of methane emissions for gas Transmission and Distribution system operators, 2019 Assessment+of+methane+emissions+for+gas+Transmission+and+Distribution+system+ operator.pdf?t=1602849054

[12] MARCOGAZ – Guidance for using the MARCOGAZ methane emissions reporting template – DSO, TSO, LNG receiving terminals and UGS

[13] MGP Reducing methane emissions: Equipment leaks

[14] MGP Reducing methane emissions: Identification, detection, measurement and quantification

[15] MGP Reducing methane emissions: Transmission, storage, LNG terminals and distribution

[16] Oil and Gas Methane Partnership Technical Guidance Documents

[17] Regulation (EC) No 715/2009 of the European Parliament and of the Council of 13 July 2009

[18] US EPA – ‘Method 21: Determination of volatile organic compound leaks’