ASTM D5192-2008 Standard Practice for Collection of Coal Samples from Core.pdf

1、Designation: D 5192 08Standard Practice forCollection of Coal Samples from Core1This standard is issued under the fixed designation D 5192; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in pare

2、ntheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice describes procedures for collecting andhandling a coal sample from a core recovered from a borehole.1.2 The values stated in SI units

3、are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practi

4、ces and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 121 Terminology of Coal and CokeD 388 Classification of Coals by RankD 1412 Test Method for Equilibrium Moisture of Coal at 96to 97 Percent Relative Humidity and 30CD 2013 Practic

5、e for Preparing Coal Samples for AnalysisD 2796 Terminology Relating to Megascopic Descriptionof Coal and Coal Seams and Microscopical Descriptionand Analysis of Coal3D 4371 Test Method for Determining the Washability Char-acteristics of CoalD 4596 Practice for Collection of Channel Samples of Coali

6、n a Mine3. Terminology3.1 DefinitionsFor additional definitions of terms, refer toTerminology D 121.3.1.1 borehole, nthe circular hole through soil and rockstrata made by boring.3.1.2 caves or washouts, nzones of increased hole diam-eter caused by rock fragments that fall from the walls of aborehole

7、 and can block the hole or contaminate the cuttingsand which erode or abrade the sidewall of the borehole by theaction of the drilling. These zones can affect the accuracy ofcertain geophysical logs (especially density). Corrections toother geophysical logs can be made if a caliper log is available.

8、The most common causes of caves or washouts include soft orfractured lithologies, the presence of water-producing zones,and the downhole pressure of the drilling medium (fluid or air)that often causes differential erosion of various strata within theborehole.3.1.3 concretion, nin a geological sense,

9、 a mass of min-eral matter found in rock of a composition different from itsown and produced by deposition from aqueous solution in therock.3.1.4 core, nin drilling, a cylindrical section of rock (coal)that is usually 5 to 10 cm in diameter, taken as part of theinterval penetrated by a core bit and

10、brought to the surface forgeologic examination, representative sampling, and laboratoryanalyses.3.1.5 core barrels, ntwo nested tubes above the bit of acore drill, the outer rotating with the bit, the inner receiving andpreserving a continuous section or core of the material pen-etrated. The followi

11、ng two types of inner barrels are commonlyused.3.1.5.1 split-tube barrel, na type of inner barrel consistingof two longitudinal halves of pipe bound together by reinforcedtape at intervals along the barrel length that allows easy accessto a relatively intact core (by cutting the tape). (This is thep

12、referred barrel type for coal exploration, when available.)3.1.5.2 solid-tube barrel, na type of inner barrel consist-ing of a single solid-walled length of pipe in which removal ofthe core is accomplished by mechanical or hydraulic pressureat one end of the pipe thus extruding the core onto a core

13、tray.(The core is likely to be less intact than when a split-tube barrelis used.)3.1.6 core sample, nthat part of a core of rock or coalobtained so as to accurately represent a thickness of a unitpenetrating by drilling.3.1.7 geophysical log, na graphic record of the measuredor computed physical cha

14、racteristics of the rock section en-countered in a borehole, plotted as a continuous function ofdepth. Measurements are made by a sonde, which contains thedetectors, as it is withdrawn from the borehole by a wire line.Several measurements are usually made simultaneously, and1This practice is under t

15、he jurisdiction of ASTM Committee D05 on Coal andCoke and is the direct responsibility of Subcommittee D05.18 on Classification ofCoals.Current edition approved May 1, 2008. Published May 2008. Originallyapproved in 1991. Last previous edition approved in 2007 as D 5192 07.2For referenced ASTM stand

16、ards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Cons

17、hohocken, PA 19428-2959, United States.the resulting curves are displayed side by side on the commondepth scale. A common suite of logs used in coal explorationinclude caliper, density (gamma-gamma), natural gamma, andresistivity.3.1.7.1 caliper log, na continuous mechanical measure-ment of the diam

18、eter and thus the rugosity of the borehole. Thetool identifies zones where swelling or cavings (washouts)have occurred during drilling. The tools value is in allowingqualitative or quantitative corrections to be made to othergeophysical logs which are affected by borehole size (espe-cially density).

19、3.1.7.2 density log (gamma-gamma log), nmeasures elec-tron density within lithologic units which is related to theirbulk density. The wireline tool records the intensity of gammaradiation (in counts per second) from a nuclear source withinthe tool after it has been attenuated and backscattered bylit

20、hologies within the borehole. Due to the distinctly lowdensity of coals, the density log is essential in coal explorationfor identifying coal seams and coal-seam partings. The bias/resolution of density logs can be affected by source-detectorspacing (closer spacing increases resolution), borehole si

21、ze andirregularities (see caves or washouts), and the presence ofcasing and logging speed.3.1.7.3 natural gamma-ray log, na record of the naturalradioactivity of the lithologies encountered in the boreholeenvironment. During recording of geophysical logs, theamount of natural radiation is recorded a

22、nd presented in eithercounts per second (CPS) or American Petroleum Institute(API) units. Unlike many other log types, a representativenatural gamma log can be obtained where borehole or fluidconditions, or both, are not optimal or where casing is present.The natural gamma log is most often used in

23、the coalenvironment for identifying classic lithologies and differenti-ating coal seams and coal-seam partings.3.1.7.4 resistivity log, na measure of the voltage differen-tial of strata along the walls of a borehole when electricalcurrent is passed through the strata. The resistivity log requiresa f

24、luid-filled hole to constantly provide a conductive mediumbetween electrodes on the tool. The spacing between theelectrodes determines the precision of the bed boundaryrelationships in much the same manner as with the density log.The resistivity log is useful primarily in conjunction with otherlog t

25、ypes. The logs are affected by casing, logging speed,electrode spacing, formation porosity, and resistivity changesin the borehole fluid.3.1.8 floor, nthe rock material immediately underlying acoal bed.3.1.9 roof, nthe rock material immediately overlying acoal bed.3.1.10 sonde, nan elongate cylindri

26、cal tool assembly usedin a borehole to acquire a geophysical log.4. Summary of Practice4.1 At selected sites in a deposit of coal, a borehole is drilledand the core containing the coal and surrounding strata of rockis recovered.4.2 The coal core is cleaned of drilling fluid, if necessary,properly de

27、scribed, and packaged so that loss of moisture isminimized. From this core, coal and roof and floor material ofinterest are collected for analysis and testing.5. Significance and Use5.1 A properly collected sample that includes the total coalbed interval provides a sample that is a representative cr

28、osssection of the coal bed at the point of sampling. Core samplesare taken for subsequent testing needed for evaluation of coalquality and characterization for commercial evaluations, forplanning of mining operations to maintain coal quality, for thedetermination of coal rank in accordance with Clas

29、sificationD 388, and for geologic coal resource studies.NOTE 1Because of the potential for lateral variability, a sample maynot represent the quality of the coal bed at another sample point. Thereliability of the data generated from core samples is dependent on thenumber and spacing of the sample po

30、ints and the variability of the coalcharacteristics in a given area.5.2 Moisture determined directly from a core sample shallbe considered questionable in any core sample because ofpossible contamination from drilling fluids and groundwater. Ifa more representative estimate of the inherent moisture

31、contentof the core sample (with the exception of certain low-rankcoals) is desired, the sample should be analyzed according toTest Method D 1412.6. Apparatus6.1 Steel Measuring Tape, not less than 10 m (30 ft) long.6.2 Rock Hammer, Chisel, or Pick, with file for sharpening.6.3 Water Source, to provi

32、de fresh, clean water for rinsingdrilling mud from cut surface of the core.6.4 Waterproof Marking Pencils that are visible on coal,such as a yellow lumber crayon.6.5 Polyethylene Bags, Tubing, or Sheets, 0.1 mm (4 mil) orthicker.6.6 Core Tray, constructed of wood, plastic, or metal, ontowhich to ext

33、rude the core from the core barrel.6.7 Boxes for Core Storage, constructed of wood, plastic, orcoated cardboard or if the core is to remain stratigraphicallyoriented, use containers such as polyvinyl chloride (PVC) pipe.6.8 Tags and Waterproof Marking Pens, for sample identi-fication and for marking

34、 depths, orientation, and so forth, onthe plastic sheeting.6.9 Notebook and Pencil, or other means for record keeping.6.10 Waterproof Container, to hold sample tag.6.11 Geophysical Logging Unit (optional), consisting ofrecording equipment and sondes for high-resolution densityand caliper logs and po

35、ssibly gamma and resistivity logs.7. Planning for Sampling7.1 Obtain information such as geologic, topographic, andland ownership for locating suitable sites for drilling. Choosesites that will best satisfy the purpose of sampling.7.2 A core approximately 47 mm (1.87 in.) in diameteryields a suffici

36、ent sample for most purposes. Minimum samplemass requirements for analytical tests, such as washabilitytesting, may dictate a sample mass that can only be obtainedfrom larger diameter cores or multiple separate cores.NOTE 2The diameter and length of the core (or number of separateD5192082cores) requ

37、ired to obtain a desired mass of sample may be estimated fromthe density of coal, approximately 1.3 to 1.35 g/cm3. The selecteddiameter of the core can have an effect on the representativeness ofsubsamples obtained from the core sample for various types of testing. Asan example in washability testin

38、g, the diameter of the core should be atleast three times the largest dimension of the topsize of any subsamples tobe obtained from the core sample. For information on determining thewashability characteristics of coal, see Test Method D 4371 and the reportby Wizzard.4A larger diameter core can also

39、 be necessary to obtain a morerepresentative sample if the quality of the coal varies greatly from layer tolayer in the seam.7.3 Increment SamplingWhere differences of coal qualityparameters exist among different layers or benches in the samecoal seam or where the seam is thick, it is best to sample

40、 andanalyze the seam in vertical increments.7.3.1 Compositing5Data obtained from the separateanalyses of the vertical core increments can be composited bycalculation, preferably by sample mass if sufficient informationsuch as core length and density has been measured for eachincrement.Alternatively,

41、 a composite sample of the entire seamcan be produced by combining representative splits of theincrements by increment thickness for the determination ofwhole core characteristics. The use of an ash/density relation-ship for the specific geographic area and seam being studiedcan be helpful in valida

42、ting direct density measurements.Extreme care and cross-checking should be exercised whencombining a sample composite for analysis or when calculatinga composite analysis from the analysis of increments. Somecoal quality parameters are not additive in a linear fashion andcannot be accurately determi

43、ned by calculated compositing.Fusion temperatures of ash and Hardgrove grindability andGieseler fluidity indices are examples of physical propertiesthat are nonadditive and best determined on whole samples.7.4 Sampling Plans for Different Purposes:7.4.1 Variations in the purpose of sampling and in c

44、ondi-tions encountered in the field may preclude the establishmentof rigid procedures covering every sampling situation. There-fore, formulate a plan taking into account the conditions ofdrilling, the purpose of the sampling, and the known charac-teristics of the coal seam. Characteristics include l

45、ateral orvertical variations in coal quality and occurrences of persistentmineral parting or concretions within a seam.7.4.2 Sampling Plan for Classification According to Rank:7.4.2.1 A minimum of three, but preferably five or more,whole-seam samples are required to characterize the rank ofthe coal

46、in a given area in accordance with ClassificationD 388.7.4.2.2 All roof and floor rock, all mineral partings morethan 10 mm (38 in.) thick, and mineralized lenses or concre-tions (such as sulfur balls) more than 13 mm (12 in.) thick and50 mm (2 in.) wide shall be excluded from the sample.Angularor w

47、edge-shaped mineral lenses or concretions that are notcontinuous shall be excluded from the samples if the volumeexceeds that of a parting 10 mm thick. (Refer to PracticeD 4596.)NOTE 3In most cases a single whole-seam sample is used to identifythe one rank of coal present in the seam. However, when

48、more than onerank is thought to be present, it is acceptable to collect incrementalsamples to identify and define the coals of differing ranks.8. Core Recovery8.1 Recovery for Classification According to Rank andSome Other PurposesThe recovery of 100 % of the entireseam is not possible on every core

49、 under even the best of fieldconditions. However, useful information such as apparent rankcan many times be obtained from cores where less than 100 %of the seam has been recovered. When portions of the intervalhave been lost, the following information should be recorded:(1) the percent recovery and (2) the estimated location andthickness of the lost intervals. Use of data from cores thatrepresent less than 100 % of the total seam thickness shall beidentified as such and used with caution.8.2 Determining Recovery From Comparison of Geophysi-cal Logs and Core5