ASTM D7569/D7569M-10(2015)e1
(Practice)Standard Practice for Determination of Gas Content of Coal—Direct Desorption Method
Standard Practice for Determination of Gas Content of Coal—Direct Desorption Method
SIGNIFICANCE AND USE
5.1 Canister desorption is a widely used technique to measure the gas content of coal. The gas content data when normalized to volume/weight and multiplied by coal mass is used to estimate the gas in place in an area around the cored well.
SCOPE
1.1 This practice describes methods for the direct determination of the gas content of coal by desorption using samples obtained by drill coring methods from the surface. It sets out guidelines for the equipment construction, sample preparation and testing procedure, and method of calculation.
1.2 Indirect methods for the determination of the gas content of coal (not covered in this practice) are based on either the gas absorption characteristics of coal under a given pressure and temperature condition or other empirical data that relate the gas content of coal to such other parameters as coal rank, depth of cover, or gas emission rate.
1.3 This practice covers the following two direct methods, which vary only in the time allowed for the gas to desorb from the core, or sidewall core, before final crushing:
1.3.1 The slow desorption method in which volumetric readings of gas content are taken frequently (for example, every 10 to 15 min) during the first few hours, followed by hourly measurements for several hours, and then measurements on 24-h intervals until no or very little gas is being desorbed for an extended period of time.
1.3.2 The fast desorption method in which after initial desorbed gas measurements to obtain data for lost gas calculations are taken, the canister is opened and the sample is transferred to the coal crusher. The remaining gas volume is measured on a crushed sample.
1.4 This practice is confined to the direct method using core, or sidewall core obtained from drilling. The practice can be applied to drill cuttings samples; however, the use of cuttings is not recommended because the results may be misleading and are difficult to compare to the results obtained from core desorption. The interpretation of the results does not fall within the scope of the practice.
1.5 Units—The values stated in either SI units or inch-pound units are to be regarded separately as the standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
´1
Designation: D7569/D7569M − 10 (Reapproved 2015)
Standard Practice for
Determination of Gas Content of Coal—Direct Desorption
Method
This standard is issued under the fixed designation D7569/D7569M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Designation was corrected editorially in February 2015.
1. Scope 1.5 Units—The values stated in either SI units or inch-
pound units are to be regarded separately as the standard. The
1.1 This practice describes methods for the direct determi-
values stated in each system may not be exact equivalents;
nation of the gas content of coal by desorption using samples
therefore,eachsystemshallbeusedindependentlyoftheother.
obtained by drill coring methods from the surface. It sets out
Combining values from the two systems may result in noncon-
guidelines for the equipment construction, sample preparation
formance with the standard.
and testing procedure, and method of calculation.
1.2 Indirect methods for the determination of the gas con- 1.6 This standard does not purport to address all of the
tentofcoal(notcoveredinthispractice)arebasedoneitherthe
safety concerns, if any, associated with its use. It is the
gas absorption characteristics of coal under a given pressure
responsibility of the user of this standard to establish appro-
and temperature condition or other empirical data that relate
priate safety and health practices and determine the applica-
the gas content of coal to such other parameters as coal rank,
bility of regulatory limitations prior to use.
depth of cover, or gas emission rate.
1.3 This practice covers the following two direct methods, 2. Referenced Documents
which vary only in the time allowed for the gas to desorb from
2.1 ASTM Standards:
the core, or sidewall core, before final crushing:
D121 Terminology of Coal and Coke
1.3.1 The slow desorption method in which volumetric
D167 Test Method for Apparent and True Specific Gravity
readings of gas content are taken frequently (for example,
and Porosity of Lump Coke
every 10 to 15 min) during the first few hours, followed by
D1412 Test Method for Equilibrium Moisture of Coal at 96
hourly measurements for several hours, and then measure-
to 97 Percent Relative Humidity and 30°C
ments on 24-h intervals until no or very little gas is being
D2799 Test Method for Microscopical Determination of the
desorbed for an extended period of time.
Maceral Composition of Coal
1.3.2 The fast desorption method in which after initial
desorbed gas measurements to obtain data for lost gas calcu- D3172 Practice for Proximate Analysis of Coal and Coke
lations are taken, the canister is opened and the sample is D3173 Test Method for Moisture in the Analysis Sample of
transferred to the coal crusher. The remaining gas volume is
Coal and Coke
measured on a crushed sample.
D3174 Test Method forAsh in theAnalysis Sample of Coal
and Coke from Coal
1.4 Thispracticeisconfinedtothedirectmethodusingcore,
D3176 Practice for Ultimate Analysis of Coal and Coke
or sidewall core obtained from drilling. The practice can be
D3180 Practice for Calculating Coal and Coke Analyses
applied to drill cuttings samples; however, the use of cuttings
from As-Determined to Different Bases
isnotrecommendedbecausetheresultsmaybemisleadingand
D3302 Test Method for Total Moisture in Coal
are difficult to compare to the results obtained from core
D5192 Practice for Collection of Coal Samples from Core
desorption.Theinterpretationoftheresultsdoesnotfallwithin
the scope of the practice. E1272 Specification for Laboratory Glass Graduated Cylin-
ders
This practice is under the jurisdiction of ASTM Committee D05 on Coal and
Coke and is the direct responsibility of Subcommittee D05.21 on Methods of
Analysis. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Feb. 1, 2015. Published February 2015. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2010. Last previous edition approved as D7569–10. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
D7569_D7569-10R15E01. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D7569/D7569M − 10 (2015)
2.2 Australian Standard: 3.1.8 canister, n—container that can be sealed into which a
AS 3980 Guide to the determination of gas content of coal sample is placed to allow desorption to occur.
coal—Direct desorption method
3.1.8.1 Discussion—The reduction in pressure to atmo-
spheric pressure (at surface) causes the sample to release gas
2.3 ISO Standard:
into the canister. By measuring the amount of gas released and
ISO 6706 Plastics laboratory ware—Graduated measuring
the weight of the sample, the gas content can be determined.
cylinders
Gas content is conventionally reported in units of cubic
2.4 DIN Standard:
3 3
centimetres/gram (cm /g), cubic metres/tonne (m /ton), or
DIN 12681 Plastics laboratory ware—Graduated measuring
standard cubic feet/ton (scf/ton). (1)
cylinders
3.1.9 continuous coring, v—referstocontinuouscoringwith
3. Terminology
wireline recovery. (1)
3.1 Definitions:
3.1.10 conventional core, n—“large” diameter core (8.9 cm
3.1.1 For additional definitions of terms used in this
[3.5 in.] diameter or larger) in which the core barrel is
practice, refer to Terminology D121.
recoveredtothesurfaceafterdrillingafixedintervalbypulling
3.1.2 absolute permeability, n—permeability of a rock to a
the drill string. (1)
particular fluid when the rock is 100 % saturated with the
6 3.1.11 core, n—in drilling, a cylindrical section of rock
flowing fluid. (1)
(coal) that is usually 5 to 10 cm in diameter taken as part of the
3.1.3 absorbed gas, n—gas that is molecularly dissolved
interval penetrated by a core bit and brought to the surface for
within a liquid phase or has penetrated into the lattice structure
geologic examination, representative sampling, and laboratory
of a solid. (1)
analyses. (D121, D5192)
3.1.4 actual lost gas time, n—lost gas time determined from
3.1.12 cuttings, n—in drilling, rock fragments that break
the time at which the sample being recovered reaches a depth
away because of the action of the drill bit and are transported
where the hydrostatic pressure of the drilling fluid column
to the surface by the drilling circulation system (mud or air).
equals the original (immediately before sampling) reservoir
3.1.12.1 Discussion—Cuttings may be screened and col-
pressureinthesampletothetimeatwhichthesampleissealed
lected from the circulation medium for lithologic characteriza-
in a desorption canister.
tion or analytical tests. (2)
3.1.4.1 Discussion—Essentially, the actual lost gas time is
3.1.13 delivery tube, n—flexible tube connecting a desorp-
the amount of time between when the core starts its trip to the
tion canister to a volumetric displacement apparatus. (1)
surface and when it is sealed in the canister. (1)
3.1.5 adsorption, n—attachment, through physical or 3.1.14 desorption, n—detachment of adsorbed molecules
chemical bonding, of fluid phase molecules to an interfacial
from an interfacial surface (see adsorption). (1)
surface.
3.1.15 desorption data analysis software, n—software used
3.1.5.1 Discussion—The adsorbed phase molecules are se-
for analyzing desorption data. (1)
questered at the interfacial surface in a metastable equilibrium
3.1.16 desorption rate, n—volumetric rate at which gas
state, the stability of which is strongly affected by changes in
desorbs from a sample. (1)
temperature and pressure. (1)
3.1.17 diffusion, n—process whereby particles of liquids or
3.1.6 adsorption isotherm, n—quantitative relationship, at
gases move from a region of higher to lower concentration
constant temperature, describing how the concentration of
independent of the pressure gradient. (1)
adsorbed phase molecules at an interfacial surface varies as a
function of increasing system pressure. (1)
3.1.18 diffusivity, n—ratio of the diffusion coefficient to the
3.1.7 as-received basis, n—analytical data calculated to the square of a typical diffusion distance. (1)
moisture condition of the sample as it arrived at the laboratory
3.1.19 direct desorption method, n—method for represent-
and before any processing or conditioning.
ing desorption of gas from coal or other materials in which gas
3.1.7.1 Discussion—If the sample has been maintained in a
storage as a result of adsorption is significant.
sealed state so that there has been no gain or loss, the
3.1.19.1 Discussion—It mathematically presumes constant
as-received basis is equivalent to the moisture basis as
temperature diffusion from a sphere initially at uniform gas
sampled. (D3180, D5192, D1412, D3302)
concentration. The solution of the basic equation adopted
suggests that the measured desorbed gas volume is propor-
tional to the square root of time since the start of desorption
Available from Standards Australia Limited, 286 Sussex St., Sydney, NSW,
(time zero). The direct method is the most widely used method
2000, Australia, GPO Box 476, Sydney, NSW, 2001 Australia or via the website:
www.standards.org.au. for estimating lost gas volume. (1)
Available from the International Organization for Standardization (ISO), 1, rue
3.1.20 dry, ash-free basis, n—datacalculatedtoatheoretical
de Varembé, Case Postale 56, CH-1211 Geneva 20, Switzerland or via the website:
http://www.iso.org/. base of no moisture or ash associated with the sample.
Available from Deutsches Institut für Normung e. V., 10772 Berlin or via the
3.1.20.1 Discussion—Numerical values as established by
website: http://www2.din.de.
Test Methods D3173 and D3174 are used for converting the
The boldface numbers in parentheses refer to the list of references at the end of
this standard. as-determined data to a moisture- and ash-free basis. (D3180)
´1
D7569/D7569M − 10 (2015)
3.1.21 fast desorption method, n—after initial measure- 3.1.33 manometer, n—see volumetric displacement appara-
ments to obtain the basis for lost gas calculations, the canister tus.
is opened and the sample is transferred to a coal-crushing
3.1.34 measured gas volume, n—measured volume of gas
device that is modified so that the remaining desorbed gas
that is released from a sample into a desorption canister,
volume from the crushed coal sample can be measured.
reported at standard temperature and pressure conditions. (1)
(AS 3980)
3.1.35 mesopores, n—pores in the coal larger than 2 nm and
3.1.22 free gas, n—unabsorbed gas within the pores and
less than 50 nm. (3)
natural fractures. (1)
3.1.36 micropores, n—pores with a width of less than 2 nm.
3.1.23 gas-in-place, n—amount of gas present in a seam or
(3)
an interval of discrete thickness or in multiple seams or
3.1.37 modified direct method, n—modification of the direct
intervals determined from the gas content, bulk density,
method by the U.S. Bureau of Mines according to Diamond
thickness, and drainage area.
and Levine (4) and Diamond and Schatzel (5) to account
3.1.23.1 Discussion—Estimates of gas-in-place usually re-
precisely for changes in the concentration of gaseous species
flect total gas content, which in addition to methane, may
during desorption, with particular applications to situations in
include other gases such as carbon dioxide or nitrogen. (1)
which small amounts of gas are evolved. (1)
3.1.24 gas saturated, adv—state in which the gas content
3.1.38 quick connect fittings, n—pipe fittings designed for
(determined from direct or indirect desorption measurements)
easy and rapid connection and disconnection.
is equal to the gas storage capacity (determined from
isotherms). (1) 3.1.39 raw basis, n—basis for gas content calculation
wherebythegasvolumeisdividedbytheactualsampleweight
3.1.25 gas storage capacity, n—maximum amount of gas or
regardless of the moisture content or the presence of non-coal
gas mixtures (normalized according to the relevant basis) that
in the canister sample. (1)
can be held by a sample at various reservoir pressures,
reservoir temperature, and a specific moisture (water) content. 3.1.40 residual gas volume, n—volume of the total sorbed
(1) gas that remains in the sample after desorption into a canister
has effectively ceased (after termination of canister desorp-
3.1.26 head space volume, n—void space in a canister
tion).
containing a sample.
3.1.40.1 Discussion—Residual gas volume, as defined and
3.1.26.1 Discussion—Canister desorption measurements are
reported, can be very different for slow desorption and fast
corrected for the effect of expansion or contraction of gases in
desorption methods. Early termination of desorption followed
thecanisterheadspaceinresponsetotemperatureandpressure
bysamplecrushingwillobviouslylowerdesorbedquantitiesof
fluctuations. (1)
gas and increase the residual values. Maceral composition,
3.1.27 indirect method for the determination of the gas
lithotype composition, and the coal bench being sampled may
content of coal, n—method based on either the gas absorption
all affect permeability on small-scale samples. (1)
characteristics of coal under a given pressure and temperature
3.1.41 sidewall core, n—small diameter core taken down-
condition or other empirical data that relate the gas content of
hole by wireline methods using percussion or mechanical
coal to such other parameters as coal rank, depth of cover, or
methods to drill into the side of the borehole.
gas emission rate.
3.1.41.1 Discussion—The percussion method cores by ex-
3.1.28 in-situ basis, adj—a basis in which gas content is
plosively firing hollow core barrels into a coal seam and then
determined from a plot of gas content versus bulk density
retrieving the coal plug to the surface. The mechanical method
(determined from open-hole high-resolution bulk density log
uses hollow rotary drills to core into the coal seam, pull the
data). (1)
core plugs back into the tool, and then they are retrieved.
3.1.29 isotherm (sorption isotherm), n—quantitative
3.1.42 slow desorption method, n—volumetric readings of
relationship, at constant temperature, that describes how the
canister gas content are taken frequently (for example, every
concentration of adsorbed phase molecules at an interfacial
10 to 15 min) during the first few hours, followed by hourly
...
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
´1
Designation: D7569/D7569M − 10 (Reapproved 2015)
Standard Practice for
Determination of Gas Content of Coal—Direct Desorption
Method
This standard is issued under the fixed designation D7569/D7569M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Designation was corrected editorially in February 2015.
1. Scope 1.5 Units—The values stated in either SI units or inch-
pound units are to be regarded separately as the standard. The
1.1 This practice describes methods for the direct determi-
values stated in each system may not be exact equivalents;
nation of the gas content of coal by desorption using samples
therefore, each system shall be used independently of the other.
obtained by drill coring methods from the surface. It sets out
Combining values from the two systems may result in noncon-
guidelines for the equipment construction, sample preparation
formance with the standard.
and testing procedure, and method of calculation.
1.2 Indirect methods for the determination of the gas con-
1.6 This standard does not purport to address all of the
tent of coal (not covered in this practice) are based on either the
safety concerns, if any, associated with its use. It is the
gas absorption characteristics of coal under a given pressure
responsibility of the user of this standard to establish appro-
and temperature condition or other empirical data that relate
priate safety and health practices and determine the applica-
the gas content of coal to such other parameters as coal rank,
bility of regulatory limitations prior to use.
depth of cover, or gas emission rate.
1.3 This practice covers the following two direct methods, 2. Referenced Documents
which vary only in the time allowed for the gas to desorb from
2.1 ASTM Standards:
the core, or sidewall core, before final crushing:
D121 Terminology of Coal and Coke
1.3.1 The slow desorption method in which volumetric
D167 Test Method for Apparent and True Specific Gravity
readings of gas content are taken frequently (for example,
and Porosity of Lump Coke
every 10 to 15 min) during the first few hours, followed by
D1412 Test Method for Equilibrium Moisture of Coal at 96
hourly measurements for several hours, and then measure-
to 97 Percent Relative Humidity and 30°C
ments on 24-h intervals until no or very little gas is being
D2799 Test Method for Microscopical Determination of the
desorbed for an extended period of time.
Maceral Composition of Coal
1.3.2 The fast desorption method in which after initial
D3172 Practice for Proximate Analysis of Coal and Coke
desorbed gas measurements to obtain data for lost gas calcu-
lations are taken, the canister is opened and the sample is D3173 Test Method for Moisture in the Analysis Sample of
transferred to the coal crusher. The remaining gas volume is Coal and Coke
measured on a crushed sample.
D3174 Test Method for Ash in the Analysis Sample of Coal
and Coke from Coal
1.4 This practice is confined to the direct method using core,
D3176 Practice for Ultimate Analysis of Coal and Coke
or sidewall core obtained from drilling. The practice can be
D3180 Practice for Calculating Coal and Coke Analyses
applied to drill cuttings samples; however, the use of cuttings
from As-Determined to Different Bases
is not recommended because the results may be misleading and
D3302 Test Method for Total Moisture in Coal
are difficult to compare to the results obtained from core
desorption. The interpretation of the results does not fall within D5192 Practice for Collection of Coal Samples from Core
the scope of the practice. E1272 Specification for Laboratory Glass Graduated Cylin-
ders
This practice is under the jurisdiction of ASTM Committee D05 on Coal and
Coke and is the direct responsibility of Subcommittee D05.21 on Methods of
Analysis. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Feb. 1, 2015. Published February 2015. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2010. Last previous edition approved as D7569–10. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
D7569_D7569-10R15E01. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D7569/D7569M − 10 (2015)
2.2 Australian Standard: 3.1.8 canister, n—container that can be sealed into which a
AS 3980 Guide to the determination of gas content of coal sample is placed to allow desorption to occur.
coal—Direct desorption method
3.1.8.1 Discussion—The reduction in pressure to atmo-
spheric pressure (at surface) causes the sample to release gas
2.3 ISO Standard:
into the canister. By measuring the amount of gas released and
ISO 6706 Plastics laboratory ware—Graduated measuring
the weight of the sample, the gas content can be determined.
cylinders
Gas content is conventionally reported in units of cubic
2.4 DIN Standard:
3 3
centimetres/gram (cm /g), cubic metres/tonne (m /ton), or
DIN 12681 Plastics laboratory ware—Graduated measuring
standard cubic feet/ton (scf/ton). (1)
cylinders
3.1.9 continuous coring, v—refers to continuous coring with
3. Terminology
wireline recovery. (1)
3.1 Definitions:
3.1.10 conventional core, n—“large” diameter core (8.9 cm
3.1.1 For additional definitions of terms used in this
[3.5 in.] diameter or larger) in which the core barrel is
practice, refer to Terminology D121.
recovered to the surface after drilling a fixed interval by pulling
3.1.2 absolute permeability, n—permeability of a rock to a
the drill string. (1)
particular fluid when the rock is 100 % saturated with the
6 3.1.11 core, n—in drilling, a cylindrical section of rock
flowing fluid. (1)
(coal) that is usually 5 to 10 cm in diameter taken as part of the
3.1.3 absorbed gas, n—gas that is molecularly dissolved
interval penetrated by a core bit and brought to the surface for
within a liquid phase or has penetrated into the lattice structure
geologic examination, representative sampling, and laboratory
of a solid. (1)
analyses. (D121, D5192)
3.1.4 actual lost gas time, n—lost gas time determined from
3.1.12 cuttings, n—in drilling, rock fragments that break
the time at which the sample being recovered reaches a depth
away because of the action of the drill bit and are transported
where the hydrostatic pressure of the drilling fluid column
to the surface by the drilling circulation system (mud or air).
equals the original (immediately before sampling) reservoir
3.1.12.1 Discussion—Cuttings may be screened and col-
pressure in the sample to the time at which the sample is sealed
lected from the circulation medium for lithologic characteriza-
in a desorption canister.
tion or analytical tests. (2)
3.1.4.1 Discussion—Essentially, the actual lost gas time is
3.1.13 delivery tube, n—flexible tube connecting a desorp-
the amount of time between when the core starts its trip to the
tion canister to a volumetric displacement apparatus. (1)
surface and when it is sealed in the canister. (1)
3.1.5 adsorption, n—attachment, through physical or
3.1.14 desorption, n—detachment of adsorbed molecules
chemical bonding, of fluid phase molecules to an interfacial from an interfacial surface (see adsorption). (1)
surface.
3.1.15 desorption data analysis software, n—software used
3.1.5.1 Discussion—The adsorbed phase molecules are se-
for analyzing desorption data. (1)
questered at the interfacial surface in a metastable equilibrium
3.1.16 desorption rate, n—volumetric rate at which gas
state, the stability of which is strongly affected by changes in
desorbs from a sample. (1)
temperature and pressure. (1)
3.1.17 diffusion, n—process whereby particles of liquids or
3.1.6 adsorption isotherm, n—quantitative relationship, at
gases move from a region of higher to lower concentration
constant temperature, describing how the concentration of
independent of the pressure gradient. (1)
adsorbed phase molecules at an interfacial surface varies as a
function of increasing system pressure. (1)
3.1.18 diffusivity, n—ratio of the diffusion coefficient to the
square of a typical diffusion distance. (1)
3.1.7 as-received basis, n—analytical data calculated to the
moisture condition of the sample as it arrived at the laboratory
3.1.19 direct desorption method, n—method for represent-
and before any processing or conditioning.
ing desorption of gas from coal or other materials in which gas
3.1.7.1 Discussion—If the sample has been maintained in a
storage as a result of adsorption is significant.
sealed state so that there has been no gain or loss, the
3.1.19.1 Discussion—It mathematically presumes constant
as-received basis is equivalent to the moisture basis as
temperature diffusion from a sphere initially at uniform gas
sampled. (D3180, D5192, D1412, D3302)
concentration. The solution of the basic equation adopted
suggests that the measured desorbed gas volume is propor-
tional to the square root of time since the start of desorption
Available from Standards Australia Limited, 286 Sussex St., Sydney, NSW,
(time zero). The direct method is the most widely used method
2000, Australia, GPO Box 476, Sydney, NSW, 2001 Australia or via the website:
www.standards.org.au. for estimating lost gas volume. (1)
Available from the International Organization for Standardization (ISO), 1, rue
3.1.20 dry, ash-free basis, n—data calculated to a theoretical
de Varembé, Case Postale 56, CH-1211 Geneva 20, Switzerland or via the website:
http://www.iso.org/. base of no moisture or ash associated with the sample.
Available from Deutsches Institut für Normung e. V., 10772 Berlin or via the
3.1.20.1 Discussion—Numerical values as established by
website: http://www2.din.de.
6 Test Methods D3173 and D3174 are used for converting the
The boldface numbers in parentheses refer to the list of references at the end of
this standard. as-determined data to a moisture- and ash-free basis. (D3180)
´1
D7569/D7569M − 10 (2015)
3.1.21 fast desorption method, n—after initial measure- 3.1.33 manometer, n—see volumetric displacement appara-
ments to obtain the basis for lost gas calculations, the canister tus.
is opened and the sample is transferred to a coal-crushing
3.1.34 measured gas volume, n—measured volume of gas
device that is modified so that the remaining desorbed gas
that is released from a sample into a desorption canister,
volume from the crushed coal sample can be measured.
reported at standard temperature and pressure conditions. (1)
(AS 3980)
3.1.35 mesopores, n—pores in the coal larger than 2 nm and
3.1.22 free gas, n—unabsorbed gas within the pores and
less than 50 nm. (3)
natural fractures. (1)
3.1.36 micropores, n—pores with a width of less than 2 nm.
3.1.23 gas-in-place, n—amount of gas present in a seam or
(3)
an interval of discrete thickness or in multiple seams or
3.1.37 modified direct method, n—modification of the direct
intervals determined from the gas content, bulk density,
method by the U.S. Bureau of Mines according to Diamond
thickness, and drainage area.
and Levine (4) and Diamond and Schatzel (5) to account
3.1.23.1 Discussion—Estimates of gas-in-place usually re-
precisely for changes in the concentration of gaseous species
flect total gas content, which in addition to methane, may
during desorption, with particular applications to situations in
include other gases such as carbon dioxide or nitrogen. (1)
which small amounts of gas are evolved. (1)
3.1.24 gas saturated, adv—state in which the gas content
3.1.38 quick connect fittings, n—pipe fittings designed for
(determined from direct or indirect desorption measurements)
easy and rapid connection and disconnection.
is equal to the gas storage capacity (determined from
isotherms). (1) 3.1.39 raw basis, n—basis for gas content calculation
whereby the gas volume is divided by the actual sample weight
3.1.25 gas storage capacity, n—maximum amount of gas or
regardless of the moisture content or the presence of non-coal
gas mixtures (normalized according to the relevant basis) that
in the canister sample. (1)
can be held by a sample at various reservoir pressures,
reservoir temperature, and a specific moisture (water) content. 3.1.40 residual gas volume, n—volume of the total sorbed
(1) gas that remains in the sample after desorption into a canister
has effectively ceased (after termination of canister desorp-
3.1.26 head space volume, n—void space in a canister
tion).
containing a sample.
3.1.40.1 Discussion—Residual gas volume, as defined and
3.1.26.1 Discussion—Canister desorption measurements are
reported, can be very different for slow desorption and fast
corrected for the effect of expansion or contraction of gases in
desorption methods. Early termination of desorption followed
the canister head space in response to temperature and pressure
by sample crushing will obviously lower desorbed quantities of
fluctuations. (1)
gas and increase the residual values. Maceral composition,
3.1.27 indirect method for the determination of the gas
lithotype composition, and the coal bench being sampled may
content of coal, n—method based on either the gas absorption
all affect permeability on small-scale samples. (1)
characteristics of coal under a given pressure and temperature
3.1.41 sidewall core, n—small diameter core taken down-
condition or other empirical data that relate the gas content of
hole by wireline methods using percussion or mechanical
coal to such other parameters as coal rank, depth of cover, or
methods to drill into the side of the borehole.
gas emission rate.
3.1.41.1 Discussion—The percussion method cores by ex-
3.1.28 in-situ basis, adj—a basis in which gas content is
plosively firing hollow core barrels into a coal seam and then
determined from a plot of gas content versus bulk density
retrieving the coal plug to the surface. The mechanical method
(determined from open-hole high-resolution bulk density log
uses hollow rotary drills to core into the coal seam, pull the
data). (1)
core plugs back into the tool, and then they are retrieved.
3.1.29 isotherm (sorption isotherm), n—quantitative
3.1.42 slow desorption method, n—volumetric readings of
relationship, at constant temperature, that describes how the
canister gas content are taken frequently (for example, every
concentration of adsorbed phase molecules at an interfacial
10 to 15 min) during the first few hours, followed by hourly
surface varies as a fu
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
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Designation: D7569 − 10 D7569/D7569M − 10 (Reapproved 2015)
Standard Practice for
Determination of Gas Content of Coal—Direct Desorption
Method
This standard is issued under the fixed designation D7569;D7569/D7569M; the number immediately following the designation indicates
the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Designation was corrected editorially in February 2015.
1. Scope
1.1 This practice describes methods for the direct determination of the gas content of coal by desorption using samples obtained
by drill coring methods from the surface. It sets out guidelines for the equipment construction, sample preparation and testing
procedure, and method of calculation.
1.2 Indirect methods for the determination of the gas content of coal (not covered in this practice) are based on either the gas
absorption characteristics of coal under a given pressure and temperature condition or other empirical data that relate the gas
content of coal to such other parameters as coal rank, depth of cover, or gas emission rate.
1.3 This practice covers the following two direct methods, which vary only in the time allowed for the gas to desorb from the
core, or sidewall core, before final crushing:
1.3.1 The slow desorption method in which volumetric readings of gas content are taken frequently (for example, every 10 to
15 min) during the first few hours, followed by hourly measurements for several hours, and then measurements on 24-h intervals
until no or very little gas is being desorbed for an extended period of time.
1.3.2 The fast desorption method in which after initial desorbed gas measurements to obtain data for lost gas calculations,
calculations are taken, the canister is opened and the sample is transferred to the coal crusher. The remaining gas volume is
measured on a crushed sample.
1.4 This practice is confined to the direct method using core, or sidewall core obtained from drilling. The practice can be applied
to drill cuttings samples; however, the use of cuttings is not recommended because the results may be misleading and are difficult
to compare to the results obtained from core desorption. The interpretation of the results does not fall within the scope of the
practice.
1.5 Units—The values stated in either SI units or inch-pound units are to be regarded separately as the standard. The values
stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining
values from the two systems may result in nonconformance with the standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D121 Terminology of Coal and Coke
D167 Test Method for Apparent and True Specific Gravity and Porosity of Lump Coke
D1412 Test Method for Equilibrium Moisture of Coal at 96 to 97 Percent Relative Humidity and 30°C
D2799 Test Method for Microscopical Determination of the Maceral Composition of Coal
D3172 Practice for Proximate Analysis of Coal and Coke
D3173 Test Method for Moisture in the Analysis Sample of Coal and Coke
This practice is under the jurisdiction of ASTM Committee D05 on Coal and Coke and is the direct responsibility of Subcommittee D05.21 on Methods of Analysis.
Current edition approved Sept. 1, 2010Feb. 1, 2015. Published October 2010February 2015. Originally approved in 2010. Last previous edition approved as D7569–10.
DOI: 10.1520/D7569–10.10.1520/D7569_D7569-10R15E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D7569/D7569M − 10 (2015)
D3174 Test Method for Ash in the Analysis Sample of Coal and Coke from Coal
D3176 Practice for Ultimate Analysis of Coal and Coke
D3180 Practice for Calculating Coal and Coke Analyses from As-Determined to Different Bases
D3302 Test Method for Total Moisture in Coal
D5192 Practice for Collection of Coal Samples from Core
E1272 Specification for Laboratory Glass Graduated Cylinders
2.2 Australian Standard:
AS 3980 Guide to the determination of gas content of coal—Direct desorption method
2.3 ISO Standard:
ISO 6706 Plastics laboratory ware—Graduated measuring cylinders
2.4 DIN Standard:
DIN 12681 Plastics laboratory ware—Graduated measuring cylinders
3. Terminology
3.1 Definitions:
3.1.1 For additional definitions of terms used in this practice, refer to Terminology D121.
3.1.2 absolute permeability, n—permeability of a rock to a particular fluid when the rock is 100 % saturated with the flowing
fluid. (1)
3.1.3 absorbed gas, n—gas that is molecularly dissolved within a liquid phase or has penetrated into the lattice structure of a
solid. (1)
3.1.4 actual lost gas time, n—lost gas time determined from the time at which the sample being recovered reaches a depth where
the hydrostatic pressure of the drilling fluid column equals the original (immediately before sampling) reservoir pressure in the
sample to the time at which the sample is sealed in a desorption canister.
Available from Standards Australia Limited, 286 Sussex St., Sydney, NSW, 2000, Australia, GPO Box 476, Sydney, NSW, 2001 Australia or via the website:
www.standards.org.au.
Available from the International Organization for Standardization (ISO), 1, rue de Varembé, Case Postale 56, CH-1211 Geneva 20, Switzerland or via the website:
http://www.iso.org/.
Available from Deutsches Institut für Normung e. V., 10772 Berlin or via the website: http://www2.din.de.
The boldface numbers in parentheses refer to the list of references at the end of this standard.
3.1.4.1 Discussion—
Essentially, the actual lost gas time is the amount of time between when the core starts its trip to the surface and when it is sealed
in the canister. (1)
3.1.5 adsorption, n—attachment, through physical or chemical bonding, of fluid phase molecules to an interfacial surface.
3.1.5.1 Discussion—
The adsorbed phase molecules are sequestered at the interfacial surface in a metastable equilibrium state, the stability of which
is strongly affected by changes in temperature and pressure. (1)
3.1.6 adsorption isotherm, n—quantitative relationship, at constant temperature, describing how the concentration of adsorbed
phase molecules at an interfacial surface varies as a function of increasing system pressure. (1)
3.1.7 as-received basis, n—analytical data calculated to the moisture condition of the sample as it arrived at the laboratory and
before any processing or conditioning.
3.1.7.1 Discussion—
If the sample has been maintained in a sealed state so that there has been no gain or loss, the as-received basis is equivalent to
the moisture basis as sampled. (D3180, D5192, D1412, D3302)
3.1.8 canister, n—container that can be sealed into which a coal sample is placed to allow desorption to occur.
3.1.8.1 Discussion—
The reduction in pressure to atmospheric pressure (at surface) causes the sample to release gas into the canister. By measuring the
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D7569/D7569M − 10 (2015)
amount of gas released and the weight of the sample, the gas content can be determined. Gas content is conventionally reported
3 3
in units of cubic centimetres/gram (cm /g), cubic metres/tonne (m /ton), or standard cubic feet/ton (scf/ton). (1)
3.1.9 continuous coring, v—refers to continuous coring with wireline recovery. (1)
3.1.10 conventional core, n—“large” diameter core (8.9 cm or 3.5 in. [3.5 in.] diameter or larger) in which the core barrel is
recovered to the surface after drilling a fixed interval by pulling the drill string. (1)
3.1.11 core, n—in drilling, a cylindrical section of rock (coal) that is usually 5 to 10 cm in diameter taken as part of the interval
penetrated by a core bit and brought to the surface for geologic examination, representative sampling, and laboratory analyses.
(D121, D5192)
3.1.12 cuttings, n—in drilling, rock fragments that break away because of the action of the drill bit and are transported to the
surface by the drilling circulation system (mud or air).
3.1.12.1 Discussion—
Cuttings may be screened and collected from the circulation medium for lithologic characterization or analytical tests. (2)
3.1.13 delivery tube, n—flexible tube connecting a desorption canister to a volumetric displacement apparatus. (1)
3.1.14 desorption, n—detachment of adsorbed molecules from an interfacial surface (see adsorption). (1)
3.1.15 desorption data analysis software, n—software used for analyzing desorption data. (1)
3.1.16 desorption rate, n—volumetric rate at which gas desorbs from a sample. (1)
3.1.17 diffusion, n—process whereby particles of liquids or gases move from a region of higher to lower concentration
independent of the pressure gradient. (1)
3.1.18 diffusivity, n—ratio of the diffusion coefficient to the square of a typical diffusion distance. (1)
3.1.19 direct desorption method, n—method for representing desorption of gas from coal or other materials in which gas storage
as a result of adsorption is significant.
3.1.19.1 Discussion—
It mathematically presumes constant temperature diffusion from a sphere initially at uniform gas concentration. The solution of
the basic equation adopted suggests that the measured desorbed gas volume is proportional to the square root of time since the start
of desorption (time zero). The direct method is the most widely used method for estimating lost gas volume. (1)
3.1.20 dry, ash-free basis, n—data calculated to a theoretical base of no moisture or ash associated with the sample.
3.1.20.1 Discussion—
Numerical values as established by Test Methods D3173 and D3174 are used for converting the as-determined data to a moisture-
and ash-free basis. (D3180)
3.1.21 fast desorption method, n—after initial measurements to obtain the basis for lost gas calculations, the canister is opened
and the sample is transferred to a coal-crushing device that is modified so that the remaining desorbed gas volume from the crushed
coal sample can be measured.
(AS 3980)
3.1.22 free gas, n—unabsorbed gas within the pores and natural fractures. (1)
3.1.23 gas-in-place, n—amount of gas present in a seam or an interval of discrete thickness or in multiple seams or intervals
determined from the gas content, bulk density, thickness, and drainage area.
3.1.23.1 Discussion—
Estimates of gas-in-place usually reflect total gas content, which in addition to methane, may include othersother gases such as
carbon dioxide or nitrogen. (1)
3.1.24 gas saturated, adv—state in which the gas content (determined from direct or indirect desorption measurements) is equal
to the gas storage capacity (determined from isotherms). (1)
3.1.25 gas storage capacity, n—maximum amount of gas or gas mixtures (normalized according to the relevant basis) that can
be held by a sample at various reservoir pressures, reservoir temperature, and a specific moisture (water) content. (1)
3.1.26 head space volume, n—void space in a canister containing a sample.
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D7569/D7569M − 10 (2015)
3.1.26.1 Discussion—
Canister desorption measurements are corrected for the effect of expansion or contraction of gases in the canister head space in
response to temperature and pressure fluctuations. (1)
3.1.27 indirect method for the determination of the gas content of coal, n—method based on either the gas absorption
characteristics of coal under a given pressure and temperature condition or other empirical data that relate the gas content of coal
to such other parameters as coal rank, depth of cover, or gas emission rate.
3.1.28 in-situ basis, adj—a basis in which gas content is determined from a plot of gas content versus bulk density (determined
from open-hole high-resolution bulk density log data). (1)
3.1.29 isotherm (sorption isotherm), n—quantitative relationship, at constant temperature, that describes how the concentration
of adsorbed phase molecules at an interfacial surface varies as a function of system pressure. (1)
3.1.30 lost gas time, n—time between when the sample gas pressure falls below the reservoir pressure during sample recovery
(time zero) and the time when the sample is sealed in a desorption canister. (1)
3.1.31 lost gas volume, n—volume of gas that is released from a sample (generally under conditions of decreasing temperature
and pressure) before it can be placed in a canister and measured (between the time when the sample gas pressure falls below the
reservoir pressure during sample recovery and the time when the sample is sealed in a desorption canister). (1)
3.1.32 macropore, n—pores in the coal larger than 50 nm. (3)
3.1.33 manometer, n—see volumetric displacement apparatus.
3.1.34 measured gas volume, n—measured volume of gas that is released from a sample into a desorption canister, reported at
standard temperature and pressure conditions. (1)
3.1.35 mesopores, n—pores in the coal larger than 2 nm and less than 50 nm. (3)
3.1.36 micropores, n—pores with a width of less than 2 nm. (3)
3.1.37 modified direct method, n—modification of the direct method by the U.S. Bureau of Mines according to Diamond and
Levine (4) and Diamond and Schatzel (5) to account precisely for changes in the concentration of gaseous species during
desorption, with particular applications to situations in which small amounts of gas are evolved. (1)
3.1.38 quick connect fittings, n—pipe fittings designed for easy and rapid connection and disconnection.
3.1.39 raw basis, n—basis for gas content calculation whereby the gas volume is divided by the actual sample weight regardless
of the moisture content or the presence of non-coal in the canister sample. (1)
3.1.40 residual gas volume, n—volume of the total sorbed gas that remains in the sample after desorption into a canister has
effectively ceased (after termination of canister deso
...
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