ISO/TR 7262:2022
(Main)Natural gas — Coalbed methane quality designation and the applicability of ISO/TC 193 current standards
Natural gas — Coalbed methane quality designation and the applicability of ISO/TC 193 current standards
This document surveys the quality designation of CBM all around the world, and analyses whether ISO/TC 193 standards for sampling, test and calculation methods are applicable to CBM.
Gaz naturel — Désignation de la qualité du méthane de houille et applicabilité des normes en vigueur ISO/TC 193
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TECHNICAL ISO/TR
REPORT 7262
First edition
2022-01
Natural gas — Coalbed methane
quality designation and the
applicability of ISO/TC 193 current
standards
Gaz naturel — Désignation de la qualité du méthane de houille et
applicabilité des normes en vigueur ISO/TC 193
Reference number
ISO/TR 7262:2022(E)
© ISO 2022
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ISO/TR 7262:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
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ISO/TR 7262:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols, abbreviations and units . 4
4.1 Symbols and units . 4
4.2 Abbreviations . 4
5 Applicability of sampling standard . 4
6 Applicability of test and calculation standard . 5
6.1 General . 5
6.2 Gas composition . 5
6.2.1 General . 5
6.2.2 Major components . 5
6.2.3 Minor components . 7
6.2.4 Trace constituents . 8
6.3 Gas properties . 10
6.3.1 General . 10
6.3.2 Calorific value, relative density and Wobbe number . 10
6.3.3 Water dew point and water content . 11
6.3.4 Hydrogen dew point and Hydrocarbon liquid content . 11
6.4 Solid particulate matter . 12
Annex A (informative) Technical requirements and test methods for CBM .13
Annex B (informative) The issue of particulate matter in CBM .16
Bibliography .19
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ISO/TR 7262:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 193, Natural gas, Subcommittee SC 1,
Analysis of natural gas.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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ISO/TR 7262:2022(E)
Introduction
Coalbed Methane (CBM) is an unconventional form of natural gas and refers to methane-rich gases that
naturally exist in coal seams and surrounding rocks, see also Reference [31]. It is defined as a methane-
rich gas naturally occurring in coal seams (and surrounding rock) typically comprising of 80 % to 95 %
methane with lower proportions of ethane, propane, nitrogen and carbon dioxide (see ISO 18875).
At present, CBM is explored and developed in the United States, Canada, Australia, Russia, India, China
and a few other countries.
Typical CBM contains 80 % to 95 % or more methane and a small portion of ethane, propane, nitrogen
and carbon dioxide, but the composition of coalbed methane varies widely around the world. This
document aims to promote communication and coordination among countries and support the smooth
progress of unconventional natural gas exploration, development, production and custody transfer.
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TECHNICAL REPORT ISO/TR 7262:2022(E)
Natural gas — Coalbed methane quality designation and
the applicability of ISO/TC 193 current standards
1 Scope
This document surveys the quality designation of CBM all around the world, and analyses whether
ISO/TC 193 standards for sampling, test and calculation methods are applicable to CBM.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 14532, Natural gas — Vocabulary
ISO 18875, Coalbed methane exploration and development — Terms and definitions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14532, ISO 18875 and the
following apply.
NOTE Specific coalbed methane or coal gas mine terms are given in national documents, such as
[30]
GB/T 31537 .
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
normal reference conditions
reference conditions of pressure, temperature, and humidity (state of saturation) equal to 101,325 kPa
and 273,15 K for a gas in the dry state
[SOURCE: ISO 14532:2014, 2.6.1.3]
3.2
ISO standard reference conditions
reference conditions of pressure, temperature, and humidity (state of saturation) equal to 101,325 kPa
and 288,15 K for a real gas in the dry state
[SOURCE: ISO 14532:2014, 2.6.1.4]
3.3
direct sampling
sampling in situations where there is a direct connection between the natural gas to be sampled and
the analytical unit
[SOURCE: ISO 14532:2014, 2.3.1.1]
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3.4
indirect sampling
sampling in situations where there is no direct connection between the natural gas to be sampled and
the analytical unit
[SOURCE: ISO 14532:2014, 2.3.1.2]
3.5
representative sample
sample having the same composition as the natural gas sample when the latter is considered as
ahomogeneous whole
[SOURCE: ISO 14532:2014, 2.3.4.2]
3.6
gas chromatographic method
GC method
method of analysis by which the components of a gas mixture are separated using gas chromatography
Note 1 to entry: The sample is passed in a stream of carrier gas through a column that has different retention
properties relative to the components of interest. Different components pass through the column at different
rates and are detected as they elute from the column at different times.
[SOURCE: ISO 14532:2014, 2.2.2.1]
3.7
main component
major component
component whose content influences physical properties
[SOURCE: ISO 14532:2014, 2.5.2.2.1]
3.8
trace component
trace constituent
component present at very low levels
[SOURCE: ISO 14532:2014, 2.5.2.2.3]
3.9
total sulfur
total amount of sulfur found in coal bed methane
[SOURCE: ISO 14532:2014, 2.5.2.3.14]
3.10
compression factor
ratio of the volume of an arbitrary mass of gas at a specified pressure and temperature to the volume of
the same mass of gas under the same conditions as calculated from the ideal-gas law
[SOURCE: ISO 14532:2014, 2.6.2.2]
3.11
density
mass of gas divided by its volume at specified conditions of pressure and temperature
[SOURCE: ISO 14532:2014, 2.6.3.1]
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3.12
relative density
ratio of the mass of a gas contained within an arbitrary volume to the mass of dry air of standard
composition that would be contained in the same volume at the same reference conditions
[SOURCE: ISO 14532:2014, 2.6.3.2]
Note 1 to entry: The relative density is also defined in ISO 6976.
3.13
Wobbe index
calorific value on a volumetric basis at specified reference conditions, divided by the square root of the
relative density at the same specified metering reference conditions
[SOURCE: ISO 14532:2014, 2.6.4.3]
3.14
water dew point
temperature at a specified pressure at which water vapour condensation initiates
Note 1 to entry: For any pressure lower than the specified pressure, there is no condensation of water vapours at
this water dew point temperature.
[SOURCE: ISO 14532:2014, 2.6.5.1.1]
3.15
water content
mass concentration of the total amount of water contained in a gas
Note 1 to entry: Water content is expressed in units mass per unit volume.
Note 2 to entry: For gas below the water dew point, this means water in the form of both liquid and vapour; but
for gas above the water dew point, this means only water vapour.
Note 3 to entry: Water content can be also expressed as mole or volume fraction.
[SOURCE: ISO 14532:2014, 2.6.5.1.2]
3.16
hydrocarbon dew point
HCDP
temperature at a specified pressure at which hydrocarbon vapour condensation initiates
Note 1 to entry: In chemical thermodynamics, the “true” hydrocarbon dew point is the temperature (at a stated
pressure) at which the fugacity of the gas and liquid phases is identical. Since measurement of the dew point
involves reduction of the system temperature, this equates to the temperature at which the first appearance of
the liquid phase occurs. At this point, the quantity of liquid phase is infinitesimally small. Since no instrument or
observer is able to detect this infinitesimally small amount, the measured value by a chilled mirror instrument
(measured hydrocarbon dew point) differs from the “true” hydrocarbon dew point. Depending on the gas
composition and the sensitivity of the detection system of the automatic hydrocarbon-dew-point chilled-mirror
instrument or the observer (manual chilled mirror instrument), the measured hydrocarbon dew point can be
considerably lower than the “true” hydrocarbon dew point.
[SOURCE: ISO 14532:2014, 2.6.5.2.1]
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ISO/TR 7262:2022(E)
3.17
potential hydrocarbon liquid content
PHLC
property of natural gas defined as the amount of the condensable liquid (in milligrams) at the pressure,
p, and temperature, T, per unit volume of gas at normal conditions, that is, at a temperature of 0 °C and
a pressure of 101,325 kPa obtained by passing a representative sample of the gas through an apparatus
where it is first brought to the pressure, p, and then cooled to the temperature, T
Note 1 to entry: It is necessary to take care that only gas, not a two-phase mixture, has been withdrawn from the
pipeline.
[SOURCE: ISO 14532:2014, 2.6.5.2.3]
4 Symbols, abbreviations and units
4.1 Symbols and units
Symbol Meaning and units
d Relative density
(kJ/mol)
H Molar basis calorific value
c
(MJ/kg)
H Mass basis calorific value
m
3
H Volumetric basis calorific value (MJ/m )
V
M Mass per mole (kg/kmol)
p (Absolute) pressure (kPa)
T Celsius temperature (°C)
T Thermodynamic (absolute) temperature (K)
abs
3
V (Gas) volume (m )
3
W Wobbe index (number) (MJ/m )
Z Compression factor
3
ρ Density (kg/m )
4.2 Abbreviations
Abbreviations Meaning
CBM Coalbed methane
5 Applicability of sampling standard
ISO 10715 provides concise guidelines for the collection, conditioning and handling of representative
samples of processed natural gas streams. It also contains guidelines for sampling strategy, probe
location and the handling and design of sampling equipment. According to ISO 10715, the factors
affecting sampling representativeness include sampling material and equipment, sample containers,
sampling method, heavy hydrocarbon condensate and flow characteristics of gas sources.
[5]
NOTE Specific CBM sampling standards exist at national level .
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ISO/TR 7262:2022(E)
CBM is a kind of unconventional natural gas, which falls into the category of natural gas. It is basically
free of heavy hydrocarbon and organic sulfur compounds. The composition of CBM is simpler than that
of natural gas.
Therefore, ISO 10715 is applicable to the direct and indirect sampling of CBM.
6 Applicability of test and calculation standard
6.1 General
This clause deals with the various parameters which may be referred to in a designation of the quality
of CBM. The parameters actually selected will depend upon the purpose for which the designation is
required and it is unlikely that all the parameters listed in this document will be used.
6.2 Gas composition
6.2.1 General
CBM is composed primarily of methane and ethane with smaller amounts of propane, butane and of
non-combustible gases, carbon dioxide and nitrogen, the approximate content of each component is
shown in Table 1. The relevant ISO/TC 193 test standards for major and minor components and trace
constituents and whether these standards are applicable to CBM are shown in Table 2, 3 and 4.
Limits are not given in this document, but limits on CBM components or properties are given in Chinese
[26] [27]
national standard GB/T 26569:2011 and GB/T 26127:2010 , Chinese energy industry standard
[28] [29]
NB/T 10035:2006, Australian standard AS 4564-2011 , New Zealand Standard NZS 5442:2008
(for more information, see Annex A and Bibliography).
Table 1 — Approximate content of each component of CBM
Component Unit Approximate content range
Methane mol% 50 to 99
Ethane mol% 0,1 to 5
Propane mol% 0 to 1
Butanes mol% 0 to 1
Pentanes mol% 0 to 0,5
Nitrogen mol% 0,1 to 40
Carbon dioxide mol% 0,1 to 15
Hydrogen mol% 0 to 0,1
Oxygen mol% 0 to 5
Carbon monoxide mol% 0 to 1
Helium mol% 0 to 0,5
Argon mol% 0 to 0,5
3
Sulfur hydrogen mg/m 0 to 20
3
Total sulfur mg/m 0 to 20
6.2.2 Major components
Table 2 presents the main components of coalbed methane.
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ISO/TR 7262:2022(E)
Table 2 — Major components of CBM
Whether applicable to
Component Unit Relevant ISO/TC 193 standards
CBM
Methane mol% ISO 6974 (all parts), ISO 23978 Yes
Ethane mol% ISO 6974 (all parts),ISO 23978 Yes
Propane mol% ISO 6974 (all parts), ISO 23978 Yes
Butanes mol% ISO 6974 (all parts) Yes
Pentanes mol% ISO 6974 (all parts) Yes
Nitrogen mol% ISO 6974 (all parts), ISO 23978 Not exactly
Carbon dioxide mol% ISO 6974 (all parts), ISO 6975, ISO 23978 Not exactly
a) Methane
ISO 6974-4, ISO 6974-5, ISO 6974-6, and ISO 23978 are suitable for the determination of methane in the
range of 75 % to 100 %, 34 % to 100 %, 40 % to 100 %, and 50 % to 100 %, respectively.
Generally, the methane content in CBM is basically above 80 %, also above 50 % in some CBM with high
nitrogen or oxygen content. There is no case in which methane content in CBM is lower than 34 %.
Therefore, ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are able to meet and applicable to the
determination of methane content in CBM. ISO 6974-1, ISO 6974-2, and ISO 6974-3 are also applicable to
the determination of methane content in CBM.
b) Ethane
ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are suitable for the determination of ethane in the
range of 0,001 % to 10 %, 0,1 % to 23 %, 0,002 % to 15 %, and 0,02 % to 20 %, respectively.
Generally, the ethane content in CBM is basically lower than 5 %, and in a few exceptions, not higher
than 23 %.
Therefore, ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are able to meet and applicable to the
determination of ethane content in CBM. ISO 6974-1, ISO 6974-2 and ISO 6974-3 are also applicable to
the determination of ethane content in CBM.
c) Propane
ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are suitable for the determination of propane in the
range of 0,001 % to 3 %, 0,05 % to 10 %, 0,001 % to 5 % and 0,02 % to 10 %, respectively.
Generally, the propane content in CBM is basically lower than 1 %, and in a few exceptions, not higher
than 10 %.
Therefore, ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are able to meet and applicable to the
determination of propane content in CBM. ISO 6974-1, ISO 6974-2 and ISO 6974-3 are also applicable to
the determination of propane content in CBM.
d) Butanes
ISO 6974-4, ISO 6974-5 and ISO 6974-6 are suitable for the determination of butanes in the range of
0,001 % to 1 %, 0,01 % to 2 % and 0,000 1 % to 1 % respectively.
Generally, the butanes content in CBM is basically lower than 1 %, usually not higher than 2 %.
Therefore, ISO 6974-4, ISO 6974-5, and ISO 6974-6 are able to meet and applicable to the determination
of butanes content in CBM. ISO 6974-1, ISO 6974-2, and ISO 6974-3 are also applicable to the
determination of butanes content in CBM.
e) Pentanes
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ISO/TR 7262:2022(E)
ISO 6974-4, ISO 6974-5, and ISO 6974-6 are suitable for the determination of pentanes in the ranges of
0,001 % to 0,5 %, 0,005 % to 0.35 %, and 0,000 1 % to 0,5 %, respectively.
Generally, CBM does not contain pentanes. Pentanes are contained in some CBM but the content is
basically below 0,5 %.
Therefore, ISO 6974-4, ISO 6974-5 and ISO 6974-6 are able to meet and applicable to the determination
of pentanes content in CBM. ISO 6974-1, ISO 6974-2, and ISO 6974-3 are also applicable to the
determination of pentanes content in CBM.
f) Nitrogen
ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are suitable for the determination of nitrogen in the
ranges of 0,001 % to 15 %, 0,1 % to 22 %, 0,007 % to 40 %, and 0,02 % to 10 %, respectively.
Nitrogen content in CBM varies greatly. It’s common from less than 0,1 % to 40 %. In some CBM, the
nitrogen content is as high as 50 % or so.
Therefore, ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are basically able to meet and applicable to
the determination of nitrogen content in CBM in most cases. ISO 6974-1, ISO 6974-2, and ISO 6974-3 are
also applicable to the determination of nitrogen content in CBM. However, when the nitrogen content
in CBM is above 40 %, its concentration exceeds the upper detection limit of ISO 6974. In this case, the
applicability of ISO 6974 (all parts) to CBM detection needs to be tested and verified.
g) Carbon dioxide
ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are suitable for the determination of carbon dioxide
in the range of 0,001 % to 10 %, 0,05 % to 15 %, 0,001 % to 10 % and 0,02 % to 30 %, respectively.
Carbon dioxide content in CBM also varies greatly. It’s common from less than 0,1 % to 15 %. In a few
cases, the carbon dioxide content in CBM is higher than15 %.
Therefore, ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are basically able to meet and applicable
to the determination of carbon dioxide content in CBM in most cases. ISO 6974-1, ISO 6974-2, and
ISO 6974-3 are also applicable to the determination of carbon dioxide content in CBM. However, when
the carbon dioxide content in CBM is above 15 %, its concentration exceeds the upper detection limit of
ISO 6974. In this case, the applicability of ISO 6974 (all parts) to CBM detection needs to be tested and
verified.
6.2.3 Minor components
Table 3 presents the minority parts of coalbed methane.
Table 3 — Minor components of CBM
Component Unit Relevant ISO/TC 193 standards Whether applicable to CBM
Hydrogen mol% ISO 6974-6, ISO 6975 Yes
Oxygen mol% ISO 6974-6, ISO 6975 Not exactly
Carbon monoxide mol% ISO 6974-6 Yes
Helium mol% ISO 6974-6, ISO 6975 Yes
Argon mol% ISO 6975 Yes
a) Hydrogen
The scopes of ISO 6974-4 and ISO 6974-5 do not include the determination of hydrogen. Both ISO 6974-6
and ISO 6975 are suitable for the determination of hydrogen in the range of 0,001 % to 0,5 %.
Generally, the hydrogen content in CBM is not higher than 0,1 %.
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Therefore, ISO 6974-6 and ISO 6975 are applicable to the determination of hydrogen content in CBM.
ISO 6974-1, ISO 6974-2, and ISO 6974-3 are also applicable to the determination of hydrogen content in
CBM.
b) Oxygen
The scopes of ISO 6974-4 and ISO 6974-5 do not include the determination of oxygen. ISO 6974-6 and
ISO 6975 are suitable for the determination of oxygen in the range of 0,007 % to 5 %, and 0,001 % to
0,5 %, respectively.
Generally, the oxygen content in CBM is not higher than 5 %. The cases that the oxygen content exceeds
5 % may be due to the introduction of air during exploration and development.
Therefore, ISO 6974-6 and ISO 6975 are applicable to the determination of oxygen content in CBM in the
range of 0,001 % to 5 %. ISO 6974-1, ISO 6974-2, and ISO 6974-3 are also applicable to the determination
of oxygen content in CBM. However, when the oxygen content in CBM is above 5 %, its concentration
exceeds the upper detection limit of ISO 6974. In this case, ISO 6974 (all parts) are not applicable to CBM
any more.
It is suggested that an international, special standard for oxygen content determination will be
developed, so as to accurately determine higher oxygen content in conventional and unconventional
natural gas. New test methods for oxygen are developed at the same time to further improve the
standard system.
Note 1 to entry It is necessary to warn that if the oxygen content in natural gas is high, there can be safety
problems related to explosion and so on.
c) Carbon monoxide
The scopes of ISO 6974-4 and ISO 6974-5 do not include the determination of carbon monoxide.
ISO 6974-6 is suitable for the determination of carbon monoxide in the range of 0,001 % to 1 %.
A small amount of CBM contains carbon monoxide which is less than 1 %.
Therefore, ISO 6974-6 is applicable to the determination of carbon monoxide content in CBM. ISO 6974-1,
ISO 6974-2, and ISO 6974-3 are also applicable to the determination of carbon monoxide content in CBM.
d) Helium
The scopes of ISO 6974-4 and ISO 6974-5 do not include the determination of helium. ISO 6974-6 and
ISO 6975 are suitable for the determination of helium in the range of 0,002 % to 0,5 % and 0,001 % to
0,5 %, respectively.
Generally, the helium content in CBM is less than 0,5 %.
Therefore, ISO 6974-6 and ISO 6975 are applicable to the determination of helium content in CBM.
ISO 6974-1, ISO 6974-2, and ISO 6974-3 are also applicable to the determination of helium content in
CBM.
e) Argon
The scopes of ISO 6974-4, ISO 6974-5 and ISO 6974-6 do not include the determination of argon.
ISO 6975 is suitable for the determination of argon in the range of 0,001 % to 0,5 %.
Generally, the argon content in CBM is less than 0,5 %.
Therefore, ISO 6975 is applicable to the determination of argon content in CBM.
6.2.4 Trace constituents
The traces that can usually be found in coalbed methane are listed in Table 4.
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ISO/TR 7262:2022(E)
Table 4 — Trace constituents of CBM
Constituent Unit Relevant ISO/TC 193 standards Whether applicable to CBM
3
Hydrogen sulfide mg/m ISO 19739, ISO 23978 Yes
3
Total sulfur mg/m ISO 16960, ISO 20729 Yes
3
Mercury μg/m ISO 6978-1, ISO 6978-2 Yes
a) Hydrogen sulfide
There are several methods for the determination of sulfur compounds described in annexes of
ISO 19739, of Which Annex C “GC method using capillary column and FPD“ and Annex H “GC method
using capillary column and SCD” are both suitable for the determination of hydrogen sulfide in the
3 3
range of 0,5 mg/m to 600 mg/m . Annex D “GC method using ED” and Annex E “GC method using MSD”
3 3
are both suitable for the determination of hydrogen sulfide in the range of 0,1 mg/m to 100 mg/m .
Annex F “GC method using AED”, Annex G “GC methods using column switching and FPD”, and Annex I
“GC method using capillary column and PFPD” are all applicable to the determination of hydrogen
sulfide, but do not specify the detection ranges.
ISO 23978 are suitable for the determination of hydrogen sulfide in the range of 0,02 % to 10 %.
3 3
Generally, the hydrogen sulfide content in CBM is less than 6 mg/m ,and about 20 mg/m when it is
higher.
Therefore, ISO 19739 and ISO 23978 are applicable to the determination of hydrogen sulfide in CBM.
b) Total sulfur
ISO 16960 and ISO 20729 are suitable for the determination of total sulfur content in CBM in the range
3 3 3 3
of 1 mg/m to 200 mg/m and 1 mg/m to 150 mg/m , respectively.
3 3
Generally, the total sulfur content in CBM is less than 6 mg/m , and about 20 mg/m w
...
TECHNICAL ISO/TR
REPORT 7262
First edition
Natural gas — Coalbed methane
quality designation and the
adaptability of actual ISO/TC 193
standards
Gaz naturel — Désignation de la qualité du méthane de houille et
applicabilité des normes en vigueur ISO/TC 193
PROOF/ÉPREUVE
Reference number
ISO/TR 7262:2021(E)
© ISO 2021
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ISO/TR 7262:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
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ISO/TR 7262:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols, abbreviations and units . 4
4.1 Symbols and units . 4
4.2 Abbreviations . 4
5 Applicability of sampling standard . 4
6 Applicability of test and calculation standard . 5
6.1 General . 5
6.2 Gas composition . 5
6.2.1 General . 5
6.2.2 Major components . 5
6.2.3 Minor components . 7
6.2.4 Trace constituents . 8
6.3 Gas properties . 10
6.3.1 General . 10
6.3.2 Calorific value, relative density and Wobbe number . 10
6.3.3 Water dew point and water content . 11
6.3.4 Hydrogen dew point and Hydrocarbon liquid content . 11
6.4 Solid particulate matter . 12
Annex A (informative) Technical requirements and test methods for CBM .13
Annex B (informative) The issue of particulate matter in CBM .16
Bibliography .19
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ISO/TR 7262:2021(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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Analysis of natural gas.
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ISO/TR 7262:2021(E)
Introduction
Coalbed Methane (CBM) is an unconventional form of natural gas and refers to methane-rich gases that
naturally exist in coal seams and surrounding rocks, see also Reference [31]. It is defined as a methane-
rich gas naturally occurring in coal seams (and surrounding rock) typically comprising of 80 % to 95 %
methane with lower proportions of ethane, propane, nitrogen and carbon dioxide (see ISO 18875).
At present, CBM is explored and developed in the United States, Canada, Australia, Russia, India, China
and a few other countries.
Typical CBM contains 80 % to 95 % or more methane and a small portion of ethane, propane, nitrogen
and carbon dioxide, but the composition of coalbed methane varies widely around the world. This
document aims to promote communication and coordination among countries and support the smooth
progress of unconventional natural gas exploration, development, production and custody transfer.
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TECHNICAL REPORT ISO/TR 7262:2021(E)
Natural gas — Coalbed methane quality designation and
the adaptability of actual ISO/TC 193 standards
1 Scope
This document surveys the quality designation of CBM all around the world, and analyses whether
ISO/TC 193 standards for sampling, test and calculation methods are applicable to CBM.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 14532, Natural gas — Vocabulary
ISO 18875, Coalbed methane exploration and development — Terms and definitions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14532, ISO 18875 and the
following apply.
NOTE Specific coalbed methane or coal gas mine terms are given in national documents, such as
[30]
GB/T 31537 .
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
normal reference conditions
reference conditions of pressure, temperature, and humidity (state of saturation) equal to 101,325 kPa
and 273,15 K for a gas in the dry state
[SOURCE: ISO 14532:2014, 2.6.1.3]
3.2
ISO standard reference conditions
reference conditions of pressure, temperature, and humidity (state of saturation) equal to 101,325 kPa
and 288,15 K for a real gas in the dry state
[SOURCE: ISO 14532:2014, 2.6.1.4]
3.3
direct sampling
sampling in situations where there is a direct connection between the natural gas to be sampled and
the analytical unit
[SOURCE: ISO 14532:2014, 2.3.1.1]
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3.4
indirect sampling
sampling in situations where there is no direct connection between the natural gas to be sampled and
the analytical unit
[SOURCE: ISO 14532:2014, 2.3.1.2]
3.5
representative sample
sample having the same composition as the natural gas sample when the latter is considered as
ahomogeneous whole
[SOURCE: ISO 14532:2014, 2.3.4.2]
3.6
gas chromatographic method
GC method
method of analysis by which the components of a gas mixture are separated using gas chromatography
Note 1 to entry: The sample is passed in a stream of carrier gas through a column that has different retention
properties relative to the components of interest. Different components pass through the column at different
rates and are detected as they elute from the column at different times.
[SOURCE: ISO 14532:2014, 2.2.2.1]
3.7
main component
major component
component whose content influences physical properties
[SOURCE: ISO 14532:2014, 2.5.2.2.1]
3.8
trace component
trace constituent
component present at very low levels
[SOURCE: ISO 14532:2014, 2.5.2.2.3]
3.9
total sulfur
total amount of sulfur found in coal bed methane
[SOURCE: ISO 14532:2014, 2.5.2.3.14]
3.10
compression factor
ratio of the volume of an arbitrary mass of gas at a specified pressure and temperature to the volume of
the same mass of gas under the same conditions as calculated from the ideal-gas law
[SOURCE: ISO 14532:2014, 2.6.2.2]
3.11
density
mass of gas divided by its volume at specified conditions of pressure and temperature
[SOURCE: ISO 14532:2014, 2.6.3.1]
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3.12
relative density
ratio of the mass of a gas contained within an arbitrary volume to the mass of dry air of standard
composition that would be contained in the same volume at the same reference conditions
[SOURCE: ISO 14532:2014, 2.6.3.2]
Note 1 to entry: The relative density is also defined in ISO 6976.
3.13
Wobbe index
calorific value on a volumetric basis at specified reference conditions, divided by the square root of the
relative density at the same specified metering reference conditions
[SOURCE: ISO 14532:2014, 2.6.4.3]
3.14
water dew point
temperature at a specified pressure at which water vapour condensation initiates
Note 1 to entry: For any pressure lower than the specified pressure, there is no condensation of water vapours at
this water dew point temperature.
[SOURCE: ISO 14532:2014, 2.6.5.1.1]
3.15
water content
mass concentration of the total amount of water contained in a gas
Note 1 to entry: Water content is expressed in units mass per unit volume.
Note 2 to entry: For gas below the water dew point, this means water in the form of both liquid and vapour; but
for gas above the water dew point, this means only water vapour.
Note 3 to entry: Water content can be also expressed as mole or volume fraction.
[SOURCE: ISO 14532:2014, 2.6.5.1.2]
3.16
hydrocarbon dew point
HCDP
temperature at a specified pressure at which hydrocarbon vapour condensation initiates
Note 1 to entry: In chemical thermodynamics, the “true” hydrocarbon dew point is the temperature (at a stated
pressure) at which the fugacity of the gas and liquid phases is identical. Since measurement of the dew point
involves reduction of the system temperature, this equates to the temperature at which the first appearance of
the liquid phase occurs. At this point, the quantity of liquid phase is infinitesimally small. Since no instrument or
observer is able to detect this infinitesimally small amount, the measured value by a chilled mirror instrument
(measured hydrocarbon dew point) differs from the “true” hydrocarbon dew point. Depending on the gas
composition and the sensitivity of the detection system of the automatic hydrocarbon-dew-point chilled-mirror
instrument or the observer (manual chilled mirror instrument), the measured hydrocarbon dew point can be
considerably lower than the “true” hydrocarbon dew point.
[SOURCE: ISO 14532:2014, 2.6.5.2.1]
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3.17
potential hydrocarbon liquid content
PHLC
property of natural gas defined as the amount of the condensable liquid (in milligrams) at the pressure,
p, and temperature, T, per unit volume of gas at normal conditions, that is, at a temperature of 0 °C and
a pressure of 101,325 kPa obtained by passing a representative sample of the gas through an apparatus
where it is first brought to the pressure, p, and then cooled to the temperature, T
Note 1 to entry: It is necessary to take care that only gas, not a two-phase mixture, has been withdrawn from the
pipeline.
[SOURCE: ISO 14532:2014, 2.6.5.2.3]
4 Symbols, abbreviations and units
4.1 Symbols and units
Symbol Meaning and units
d Relative density
(kJ/mol)
H Molar basis calorific value
c
(MJ/kg)
H Mass basis calorific value
m
3
H Volumetric basis calorific value (MJ/m )
V
M Mass per mole (kg/kmol)
p (Absolute) pressure (kPa)
T Celsius temperature (°C)
T Thermodynamic (absolute) temperature (K)
abs
3
V (Gas) volume (m )
3
W Wobbe index (number) (MJ/m )
Z Compression factor
3
ρ Density (kg/m )
4.2 Abbreviations
Abbreviations Meaning
CBM Coalbed methane
5 Applicability of sampling standard
ISO 10715 provides concise guidelines for the collection, conditioning and handling of representative
samples of processed natural gas streams. It also contains guidelines for sampling strategy, probe
location and the handling and design of sampling equipment. According to ISO 10715, the factors
affecting sampling representativeness include sampling material and equipment, sample containers,
sampling method, heavy hydrocarbon condensate and flow characteristics of gas sources.
[5]
NOTE Specific CBM sampling standards exist at national level .
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ISO/TR 7262:2021(E)
CBM is a kind of unconventional natural gas, which falls into the category of natural gas. It is basically
free of heavy hydrocarbon and organic sulfur compounds. The composition of CBM is simpler than that
of natural gas.
Therefore, ISO 10715 is applicable to the direct and indirect sampling of CBM.
6 Applicability of test and calculation standard
6.1 General
This clause deals with the various parameters which may be referred to in a designation of the quality
of CBM. The parameters actually selected will depend upon the purpose for which the designation is
required and it is unlikely that all the parameters listed in this document will be used.
6.2 Gas composition
6.2.1 General
CBM is composed primarily of methane and ethane with smaller amounts of propane, butane and of
non-combustible gases, carbon dioxide and nitrogen, the approximate content of each component is
shown in Table 1. The relevant ISO/TC 193 test standards for major and minor components and trace
constituents and whether these standards are applicable to CBM are shown in Table 2, 3 and 4.
Limits are not given in this document, but limits on CBM components or properties are given in Chinese
[26] [27]
national standard GB/T 26569:2011 and GB/T 26127:2010 , Chinese energy industry standard
[28] [29]
NB/T 10035:2006, Australian standard AS 4564-2011 , New Zealand Standard NZS 5442:2008
(for more information, see Annex A and Bibliography).
Table 1 — Approximate content of each component of CBM
Component Unit Approximate content range
Methane mol% 50 to 99
Ethane mol% 0,1 to 5
Propane mol% 0 to 1
Butanes mol% 0 to 1
Pentanes mol% 0 to 0,5
Nitrogen mol% 0,1 to 40
Carbon dioxide mol% 0,1 to 15
Hydrogen mol% 0 to 0,1
Oxygen mol% 0 to 5
Carbon monoxide mol% 0 to 1
Helium mol% 0 to 0,5
Argon mol% 0 to 0,5
3
Sulfur hydrogen mg/m 0 to 20
3
Total sulfur mg/m 0 to 20
6.2.2 Major components
Table 2 presents the main components of coalbed methane.
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Table 2 — Major components of CBM
Whether applicable to
Component Unit Relevant ISO/TC 193 standards
CBM
Methane mol% ISO 6974 (all parts), ISO 23978 Yes
Ethane mol% ISO 6974 (all parts),ISO 23978 Yes
Propane mol% ISO 6974 (all parts), ISO 23978 Yes
Butanes mol% ISO 6974 (all parts) Yes
Pentanes mol% ISO 6974 (all parts) Yes
Nitrogen mol% ISO 6974 (all parts), ISO 23978 Not exactly
Carbon dioxide mol% ISO 6974 (all parts), ISO 6975, ISO 23978 Not exactly
a) Methane
ISO 6974-4, ISO 6974-5, ISO 6974-6, and ISO 23978 are suitable for the determination of methane in the
range of 75 % to 100 %, 34 % to 100 %, 40 % to 100 %, and 50 % to 100 %, respectively.
Generally, the methane content in CBM is basically above 80 %, also above 50 % in some CBM with high
nitrogen or oxygen content. There is no case in which methane content in CBM is lower than 34 %.
Therefore, ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are able to meet and applicable to the
determination of methane content in CBM. ISO 6974-1, ISO 6974-2, and ISO 6974-3 are also applicable to
the determination of methane content in CBM.
b) Ethane
ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are suitable for the determination of ethane in the
range of 0,001 % to 10 %, 0,1 % to 23 %, 0,002 % to 15 %, and 0,02 % to 20 %, respectively.
Generally, the ethane content in CBM is basically lower than 5 %, and in a few exceptions, not higher
than 23 %.
Therefore, ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are able to meet and applicable to the
determination of ethane content in CBM. ISO 6974-1, ISO 6974-2 and ISO 6974-3 are also applicable to
the determination of ethane content in CBM.
c) Propane
ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are suitable for the determination of propane in the
range of 0,001 % to 3 %, 0,05 % to 10 %, 0,001 % to 5 % and 0,02 % to 10 %, respectively.
Generally, the propane content in CBM is basically lower than 1 %, and in a few exceptions, not higher
than 10 %.
Therefore, ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are able to meet and applicable to the
determination of propane content in CBM. ISO 6974-1, ISO 6974-2 and ISO 6974-3 are also applicable to
the determination of propane content in CBM.
d) Butanes
ISO 6974-4, ISO 6974-5 and ISO 6974-6 are suitable for the determination of butanes in the range of
0,001 % to 1 %, 0,01 % to 2 % and 0,000 1 % to 1 % respectively.
Generally, the butanes content in CBM is basically lower than 1 %, usually not higher than 2 %.
Therefore, ISO 6974-4, ISO 6974-5, and ISO 6974-6 are able to meet and applicable to the determination
of butanes content in CBM. ISO 6974-1, ISO 6974-2, and ISO 6974-3 are also applicable to the
determination of butanes content in CBM.
e) Pentanes
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ISO 6974-4, ISO 6974-5, and ISO 6974-6 are suitable for the determination of pentanes in the ranges of
0,001 % to 0,5 %, 0,005 % to 0.35 %, and 0,000 1 % to 0,5 %, respectively.
Generally, CBM does not contain pentanes. Pentanes are contained in some CBM but the content is
basically below 0,5 %.
Therefore, ISO 6974-4, ISO 6974-5 and ISO 6974-6 are able to meet and applicable to the determination
of pentanes content in CBM. ISO 6974-1, ISO 6974-2, and ISO 6974-3 are also applicable to the
determination of pentanes content in CBM.
f) Nitrogen
ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are suitable for the determination of nitrogen in the
ranges of 0,001 % to 15 %, 0,1 % to 22 %, 0,007 % to 40 %, and 0,02 % to 10 %, respectively.
Nitrogen content in CBM varies greatly. It’s common from less than 0,1 % to 40 %. In some CBM, the
nitrogen content is as high as 50 % or so.
Therefore, ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are basically able to meet and applicable to
the determination of nitrogen content in CBM in most cases. ISO 6974-1, ISO 6974-2, and ISO 6974-3 are
also applicable to the determination of nitrogen content in CBM. However, when the nitrogen content
in CBM is above 40 %, its concentration exceeds the upper detection limit of ISO 6974. In this case, the
applicability of ISO 6974 (all parts) to CBM detection needs to be tested and verified.
g) Carbon dioxide
ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are suitable for the determination of carbon dioxide
in the range of 0,001 % to 10 %, 0,05 % to 15 %, 0,001 % to 10 % and 0,02 % to 30 %, respectively.
Carbon dioxide content in CBM also varies greatly. It’s common from less than 0,1 % to 15 %. In a few
cases, the carbon dioxide content in CBM is higher than15 %.
Therefore, ISO 6974-4, ISO 6974-5, ISO 6974-6 and ISO 23978 are basically able to meet and applicable
to the determination of carbon dioxide content in CBM in most cases. ISO 6974-1, ISO 6974-2, and
ISO 6974-3 are also applicable to the determination of carbon dioxide content in CBM. However, when
the carbon dioxide content in CBM is above 15 %, its concentration exceeds the upper detection limit of
ISO 6974. In this case, the applicability of ISO 6974 (all parts) to CBM detection needs to be tested and
verified.
6.2.3 Minor components
Table 3 presents the minority parts of coalbed methane.
Table 3 — Minor components of CBM
Component Unit Relevant ISO/TC 193 standards Whether applicable to CBM
Hydrogen mol% ISO 6974-6, ISO 6975 Yes
Oxygen mol% ISO 6974-6, ISO 6975 Not exactly
Carbon monoxide mol% ISO 6974-6 Yes
Helium mol% ISO 6974-6, ISO 6975 Yes
Argon mol% ISO 6975 Yes
a) Hydrogen
The scopes of ISO 6974-4 and ISO 6974-5 do not include the determination of hydrogen. Both ISO 6974-6
and ISO 6975 are suitable for the determination of hydrogen in the range of 0,001 % to 0,5 %.
Generally, the hydrogen content in CBM is not higher than 0,1 %.
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Therefore, ISO 6974-6 and ISO 6975 are applicable to the determination of hydrogen content in CBM.
ISO 6974-1, ISO 6974-2, and ISO 6974-3 are also applicable to the determination of hydrogen content in
CBM.
b) Oxygen
The scopes of ISO 6974-4 and ISO 6974-5 do not include the determination of oxygen. ISO 6974-6 and
ISO 6975 are suitable for the determination of oxygen in the range of 0,007 % to 5 %, and 0,001 % to
0,5 %, respectively.
Generally, the oxygen content in CBM is not higher than 5 %. The cases that the oxygen content exceeds
5 % may be due to the introduction of air during exploration and development.
Therefore, ISO 6974-6 and ISO 6975 are applicable to the determination of oxygen content in CBM in the
range of 0,001 % to 5 %. ISO 6974-1, ISO 6974-2, and ISO 6974-3 are also applicable to the determination
of oxygen content in CBM. However, when the oxygen content in CBM is above 5 %, its concentration
exceeds the upper detection limit of ISO 6974. In this case, ISO 6974 (all parts) are not applicable to CBM
any more.
It is suggested that an international, special standard for oxygen content determination will be
developed, so as to accurately determine higher oxygen content in conventional and unconventional
natural gas. New test methods for oxygen are developed at the same time to further improve the
standard system.
Note 1 to entry It is necessary to warn that if the oxygen content in natural gas is high, there can be safety
problems related to explosion and so on.
c) Carbon monoxide
The scopes of ISO 6974-4 and ISO 6974-5 do not include the determination of carbon monoxide.
ISO 6974-6 is suitable for the determination of carbon monoxide in the range of 0,001 % to 1 %.
A small amount of CBM contains carbon monoxide which is less than 1 %.
Therefore, ISO 6974-6 is applicable to the determination of carbon monoxide content in CBM. ISO 6974-1,
ISO 6974-2, and ISO 6974-3 are also applicable to the determination of carbon monoxide content in CBM.
d) Helium
The scopes of ISO 6974-4 and ISO 6974-5 do not include the determination of helium. ISO 6974-6 and
ISO 6975 are suitable for the determination of helium in the range of 0,002 % to 0,5 % and 0,001 % to
0,5 %, respectively.
Generally, the helium content in CBM is less than 0,5 %.
Therefore, ISO 6974-6 and ISO 6975 are applicable to the determination of helium content in CBM.
ISO 6974-1, ISO 6974-2, and ISO 6974-3 are also applicable to the determination of helium content in
CBM.
e) Argon
The scopes of ISO 6974-4, ISO 6974-5 and ISO 6974-6 do not include the determination of argon.
ISO 6975 is suitable for the determination of argon in the range of 0,001 % to 0,5 %.
Generally, the argon content in CBM is less than 0,5 %.
Therefore, ISO 6975 is applicable to the determination of argon content in CBM.
6.2.4 Trace constituents
The traces that can usually be found in coalbed methane are listed in Table 4.
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Table 4 — Trace constituents of CBM
Constituent Unit Relevant ISO/TC 193 standards Whether applicable to CBM
3
Hydrogen sulfide mg/m ISO 19739, ISO 23978 Yes
3
Total sulfur mg/m ISO 16960, ISO 20729 Yes
3
Mercury μg/m ISO 6978-1, ISO 6978-2 Yes
a) Hydrogen sulfide
There are several methods for the determination of sulfur compounds described in annexes of
ISO 19739, of Which Annex C “GC method using capillary column and FPD“ and Annex H “GC method
using capillary column and SCD” are both suitable for the determination of hydrogen sulfide in the
3 3
range of 0,5 mg/m to 600 mg/m . Annex D “GC method using ED” and Annex E “GC method using MSD”
3 3
are both suitable for the determination of hydrogen sulfide in the range of 0,1 mg/m to 100 mg/m .
Annex F “GC method using AED”, Annex G “GC methods using column switching and FPD”, and Annex I
“GC method using capillary column and PFPD” are all applicable to the determination of hydrogen
sulfide, but do not specify the detection ranges.
ISO 23978 are suitable for the determination of hydrogen sulfide in the range of 0,02 % to 10 %.
3 3
Generally, the hydrogen sulfide content in CBM is less than 6 mg/m ,and about 20 mg/m when it is
higher.
Therefore, ISO 19739 and ISO 23978 are applicable to the determination of hydrogen sulfide in CBM.
b) Total sulfur
ISO 16960 and ISO 20729 are suitable for the determination of total sulfur content in CBM in the range
...
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