ISO 18875:2015

INTERNATIONAL ISO
STANDARD 18875
First edition
2015-12-15
Coalbed methane exploration and
development — Terms and definitions
Exploration et développement du méthane de houille — Termes et
définitions
Reference number
ISO 18875:2015(E)
©
ISO 2015

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ISO 18875:2015(E)

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ii © ISO 2015 – All rights reserved

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ISO 18875:2015(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Terms relating to geology and exploration . 1
3 Terms relating to engineering and construction . 5
4 Terms relating to development and production. 8
Bibliography .11
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ISO 18875:2015(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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The committee responsible for this document is ISO/TC 263, Coalbed methane (CBM).
iv © ISO 2015 – All rights reserved

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INTERNATIONAL STANDARD ISO 18875:2015(E)
Coalbed methane exploration and development — Terms
and definitions
1 Scope
This International Standard provides terminology on geology and exploration, engineering construction,
field development and production in coalbed methane industry. This International Standard does not
contain surface gathering.
2 Terms relating to geology and exploration
2.1
coalbed methane
CBM
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
Note 1 to entry: In common international use, this term refers to methane recovered from un-mined coal seams
using surface boreholes.
2.2
adsorption
enrichment of the absorptive gas at the external and accessible internal surfaces of a solid material
(coal matrix)
[SOURCE: ISO 15901-2:2006, 3.2]
2.3
desorption
opposite of adsorption (2.2), in which adsorbed gases leave the surface of a solid material (coal matrix)
Note 1 to entry: The liberation can be spontaneous but can be accelerated by physical actions.
[SOURCE: ISO 3529-1:1981, 1.13.2]
2.4
gas content
volume of gas per unit mass of coal, usually expressed in cubic meter of gas per ton of coal under
standard temperature and pressure (STP) conditions
3
Note 1 to entry: Unit is m /t or cm³/g. STP conditions are 100 000 Pa and 0 °C (273,15 K).
2.5
CBM content
volume of hydrocarbon gas per unit mass of coal, usually expressed in cubic meter of gas per ton of coal
under standard temperature and pressure (STP) conditions
3
Note 1 to entry: Unit is m /t or cm³/g. STP conditions are 100 000 Pa and 0 °C (273,15 K).
2.6
CBM reservoir
coal seams and surrounding rock with hydrocarbon resources that can potentially be extracted for
commercial purposes
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ISO 18875:2015(E)

2.7
initial reservoir pressure
P
i
initial gas pressure measured in a reservoir, prior to the start of production
[SOURCE: WWW.GLOSSARY.OILFIELD.SLB.COM]
2.8
pressure gradient
pressure change with distance ratio of fluid pressure in the middle of the coal seam and reservoir depth
rate of pressure change with respect to depth of coalbed methane reservoir in unit depth, MPa/m,
increasing pressure value of coalbed methane reservoir in unit depth, MPa/m
2.9
abandonment pressure
lowest pressure at which commercial production can be maintained under present economic and
technical conditions expressed by flowing bottom hole pressure (FBHP)
2.10
adsorption isotherm
relationship between the amount of gas adsorbed and the equilibrium pressure of the gas at
constant temperature
Note 1 to entry: Normally described by the Langmuir equation Vads=VL · (p/(PL+p)).
[SOURCE: ISO 15901-2:2006, 3.5]
2.11
Langmuir volume
VL
maximum adsorbed gas content per unit mass of coal at infinite pressure under particular
temperature conditions
2.12
Langmuir pressure
P
L
pressure at which half of the Langmuir volume exists within the coal under particular temperature
conditions
2.13
adsorption time
time in hour or day taken for 63,2% of the total absorbed gas to desorb from the matrix
2.14
adsorption saturation
ratio of measured gas content to the maximum adsorbed gas content in theory per unit mass of coal
under particular CBM reservoir pressure and temperature conditions
2.15
critical desorption pressure
pressure in which the gas begins to desorb from the coal matrix as the CBM reservoir pressure declines
2.16
shrinkage
contraction coefficient
decrease in volume of coal matrix after gas desorption expressed as a percentage of the initial volume
[SOURCE: ISO 14616:1997, 2.2 — modified]
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ISO 18875:2015(E)

2.17
diffusion coefficient
rate of gas diffusion through a material
2
Note 1 to entry: Expressed in m /s.
Note 2 to entry: Express flow ability of coalbed methane depending on concentration.
[SOURCE: ISO 9346:2007,3.34]
2.18
dual porosity system
rock characterized by primary porosity from original deposition and secondary porosity from some
other mechanism [cleat (2.20) or fracture (2.19)] and in which all flow to the well effectively occurs in
one porosity system, and most of the fluid is stored in the other
[SOURCE: WWW.GLOSSARY.OILFIELD.SLB.COM — modified]
2.19
fracture
natural fractures in a formation resulting from external stress, usually being associated with a
displacement
2.20
cleat
natural fractures (2.19) in a coal seam usually being associated with coalification (2.21)
Note 1 to entry: Normally in a form as two groups of parallel fractures orthogonal with each other the group with
better fracture continuity is called surface cleat (face cleat), the other group limited by surface cleat is called end
cleat (butt cleat).
2.21
coalification
process by which deposited and compacted plant remains are transformed into coal
Note 1 to entry: Includes diagenesis and metamorphism.
[SOURCE: ISO 1213-2:1992, 3.29]
2.22
coal rank
position of a coal in the coalification series from lignite coal (low rank) to anthracite (high rank),
indicating maturity in terms of chemical and physical properties
[SOURCE: ISO 7404-1:1994, 2.1.3]
2.23
CBM exploration
initial phase in coalbed methane operations that includes generation of a prospect or play or both, and
drilling of an exploration well
[SOURCE: WWW.GLOSSARY.OILFIELD.SLB.COM]
2.24
CBM resources
naturally occurring concentrations or reservoirs of coalbed methane in coal seams and surrounding
rock in such forms and amounts that economic extraction is currently or potentially feasible
[SOURCE: WWW.EIA.GOV/TOOLS/GLOSSARY]
2.25
original CBM in place
volume of coalbed methane in a reservoir prior to production
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ISO 18875:2015(E)

2.26
recovery factor
ratio of recoverable amount of hydrocarbon initially in place
[SOURCE: WWW.GLOSSARY.OILFIELD.SLB.COM]
2.27
reserve
portion of the demonstrated reserve base that is estimated to be recoverable at the time of determination
Note 1 to entry: Derived by applying a recovery factor to that component of the identified resource designated as
the demonstrated reserve base.
2.28
CBM resource abundance
amount of hydrocarbons in unit area
2.29
zone evaluation
screening of various zones to decide on one or more favorable zone through comprehensive
geological research
2.30
prospecting well
wildcat well
well drilled for the purpose of discovering a new field or reservoir in the new frontier
[SOURCE: http://www.mpgpetroleum.com/glossary.html]
2.31
appraisal well
wells drilled after gas has been discovered, in order to establish the limits of the accumulation in terms
of both the area extent and thickness of the reservoir and the volume of hydrocarbons it contains, and
in order to obtain fluid samples to investigate the distribution of fluid properties in the reservoir
2.32
dirt band
parting
layer of mineral matter lying parallel to the bedding plane in a seam of coal
[SOURCE: ISO 1213-2:1992]
2.33
ash
residue obtained by incineration of a solid mineral fuel under specified conditions
[SOURCE: ISO 1213-2:1992]
2.34
volatile matter
loss in mass, corrected for moisture, when a solid mineral fuel is heated out of contact with air under
specified conditions
[SOURCE: ISO 1213-2:1992]
2.35
proximate analysis
analysis of a solid mineral fuel reported in terms of moisture, volatile matter (2.34), ash (2.33) and fixed
carbon
[SOURCE: ISO 1213-2:1992, 3.134]
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