Difference between revisions of "Thermal maturation"

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  | part    = Predicting the occurrence of oil and gas traps
 
  | part    = Predicting the occurrence of oil and gas traps
 
  | chapter = Applied paleontology
 
  | chapter = Applied paleontology
  | frompg  = 17-1
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  | frompg  = 17-40
  | topg    = 17-65
+
  | topg    = 17-41
 
  | author  = Robert L. Fleisher, H. Richard Lane
 
  | author  = Robert L. Fleisher, H. Richard Lane
 
  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch17/ch17.htm
 
  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch17/ch17.htm
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  | isbn    = 0-89181-602-X
 
  | isbn    = 0-89181-602-X
 
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Many of the elements of basin modeling programs—maturation of source rocks, reservoir diagenesis, and [[porosity]] evolution—are affected by thermal and burial history.<ref name=ch17r91>van Gizjel, P., 1980, Characterization and identification of kerogen and bitumen and determination of thermal maturation by means of qualitative and quantitative microscopical techniques, in How to Assess Maturation and Paleotemperatures: SEPM Short Course Notes, p. 1–56.</ref><ref name=ch17r70>Pradier, B., Bertrand, P., Martinez, L., Laggoun-Defarge, F., 1991, Fluorescence of organic matter and thermal maturity assessment: Organic Geochemistry, vol. 17, no. 4, p. 511–524., 10., 1016/0146-6380(91)90115-Z</ref> Thermal maturation data used to model these parameters are usually derived from fossils.
+
Thermal maturity is the extent of heat-driven reactions that alter the composition of organic matter (e.g., conversion of sedimentary organic matter to [[petroleum]] or [[cracking]] of oil to [[gas]].) Different geochemical scales, such as [[vitrinite reflectance]], [[pyrolysis]] T<sub>max</sub>, and [[biomarker]] maturity ratios can be used to indicate the level of thermal maturity of organic matter.<ref name=Petersetal_2012>Peters, Kenneth E., David J. Curry, and Marek Kacewicz, 2012, [http://archives.datapages.com/data/specpubs/hedberg4/INTRODUCTION/INTRODUCTION.HTM An overview of basin and petroleum system modeling: Definitions and concepts], ''in'' Peters, Kenneth E., David J. Curry, and Marek Kacewicz, eds., Basin modeling: New horizons in research and applications: [http://store.aapg.org/detail.aspx?id=1106 AAPG Hedberg Series no. 4], p. 1-16.</ref>
 +
 
 +
Many of the elements of basin modeling programs—maturation of source rocks, reservoir [[diagenesis]], and [[porosity]] evolution—are affected by thermal and burial history.<ref name=ch17r91>van Gizjel, P., 1980, Characterization and identification of kerogen and bitumen and determination of thermal maturation by means of qualitative and quantitative microscopical techniques, in How to Assess Maturation and Paleotemperatures: SEPM Short Course Notes, p. 1–56.</ref><ref name=ch17r70>Pradier, B., Bertrand, P., Martinez, L., Laggoun-Defarge, F., 1991, Fluorescence of organic matter and thermal maturity assessment: Organic Geochemistry, vol. 17, no. 4, p. 511–524, DOI: 10.1016/0146-6380(91)90115-Z.</ref> Thermal maturation data used to model these parameters are usually derived from fossils.
  
 
The following table shows which fossil material changes appearance due to thermal stress and therefore can be used as organic geothermometers.
 
The following table shows which fossil material changes appearance due to thermal stress and therefore can be used as organic geothermometers.
Line 29: Line 31:
 
| Thermal Alteration Index (TAI)
 
| Thermal Alteration Index (TAI)
 
|-
 
|-
| Ostracodes
+
| Ostracods
| Ostracode Alteration Index (OAI)
+
| Ostracod Alteration Index (OAI)
 
|-
 
|-
 
| Conodonts
 
| Conodonts
Line 49: Line 51:
  
 
==Vitrinite==
 
==Vitrinite==
Vitrinite is a coaly organic maceral derived from the connective tissue of vascular plants. The reflectance of vitrinite changes with heat. Vitrinite reflectance (V<sub>r</sub> or R<sub>o</sub>), the most commonly used thermal indicator, is the benchmark for maturation studies in the petroleum and coal industries.<ref name=ch17r36>Dow, W., G., O'Connor, D., I., 1982, Kerogen maturity and type by reflected light microscopy applied to petroleum generation, in How To Assess Maturation and Paleotem-peratures: SEPM Short Course Notes, p. 79–99.</ref> This technique is primarily useful for Devonian and younger clastic sediments and coals.
+
Vitrinite is a coaly organic [[maceral]] derived from the connective tissue of vascular plants. The reflectance of vitrinite changes with heat. [[Vitrinite reflectance]] (V<sub>r</sub> or R<sub>o</sub>), the most commonly used thermal indicator, is the benchmark for maturation studies in the petroleum and coal industries.<ref name=ch17r36>Dow, W., G., O'Connor, D., I., 1982, Kerogen maturity and type by reflected light microscopy applied to petroleum generation, in How To Assess Maturation and Paleotemperatures: SEPM Short Course Notes, p. 79–99.</ref> This technique is primarily useful for Devonian and younger clastic sediments and [[coal]]s.
  
 
==Pollen and spores==
 
==Pollen and spores==
Pollen and spores are the organic-walled microfossils most commonly used for gauging paleotemperature. Fossil color, which changes with heating, is used to estimate a Thermal Alteration Index, or TAI.<ref name=ch17r82>Staplin, F., L., 1969, Sedimentary organic matter, organic metamorphism, and oil and gas occurrence: Bulletin of Canadian Petroleum Geology, vol. 17, no. 1, p. 47–66.</ref><ref name=ch17r56>Lerche, I., McKenna, T., C., 1991, Pollen translucency as a thermal maturation indicator: Journal of Petroleum Geology, vol. 14, no. 1, p. 19–36., 10., 1111/jpg., 1991., 14., issue-1</ref><ref name=ch17r62>Marshall, J., E., A., 1991, Quantitative spore colour: Journal of the Geological Society of London, vol. 148, p. 223–233., 10., 1144/gsjgs., 148., 2., 0223</ref> The use of pollen and spores lets us examine in situ fossils rather than evaluate an aggregate “kerogen soup.” Other organic-walled fossils [acritarchs, chitinozoans, graptolites, scolecodonts (annelid worm jaws), and dinoflagellates] have been examined for their visual and reflected values, but these fossil groups have not been rigorously calibrated to the standard vitrinite reflectance scale.<ref name=ch17r16>Bertrand, R., Heroux, Y., 1987, Chitinozoan, graptolite and scolecodont reflectance as an alternative to vitrinite and pyrobitumen reflectance in Ordovician and Silurian strata, Anticosti Island, Quebec, Canada: AAPG Bulletin, vol. 41, p. 951–957.</ref>
+
Pollen and spores are the organic-walled microfossils most commonly used for gauging paleotemperature. Fossil color, which changes with heating, is used to estimate a [[thermal alteration index]], or TAI.<ref name=ch17r82>Staplin, F., L., 1969, Sedimentary organic matter, organic metamorphism, and oil and gas occurrence: Bulletin of Canadian Petroleum Geology, vol. 17, no. 1, p. 47–66.</ref><ref name=ch17r56>Lerche, I., McKenna, T., C., 1991, Pollen translucency as a thermal maturation indicator: Journal of Petroleum Geology, vol. 14, no. 1, p. 19–36, DOI: 10.1111/jpg.1991.14.issue-1</ref><ref name=ch17r62>Marshall, J., E., A., 1991, Quantitative spore colour: Journal of the Geological Society of London, vol. 148, p. 223–233, DOI: 10.1144/gsjgs.148.2.0223</ref> The use of pollen and spores lets us examine in situ fossils rather than evaluate an aggregate “[[kerogen]] soup.” Other organic-walled fossils—acritarchs, chitinozoans, graptolites, scolecodonts (annelid worm jaws), and dinoflagellates—have been examined for their visual and reflected values, but these fossil groups have not been rigorously calibrated to the standard vitrinite reflectance scale.<ref name=ch17r16>Bertrand, R., Heroux, Y., 1987, [http://archives.datapages.com/data/bulletns/1986-87/data/pg/0071/0008/0950/0951.htm Chitinozoan, graptolite and scolecodont reflectance as an alternative to vitrinite and pyrobitumen reflectance in Ordovician and Silurian strata, Anticosti Island, Quebec, Canada]: AAPG Bulletin, vol. 41, p. 951–957.</ref>
  
 
==Other microfossils==
 
==Other microfossils==
Fossils composed of phosphate (conodonts), carbonate (ostracodes), and agglutinated grains (agglutinated foraminifera) are also used for geothermometry. The organic framework of these fossils responds to thermal stress with color change. Of these, conodonts (Conodont Alteration Index, or CAI) are the most widely used<ref name=ch17r37>Epstein, A. G., Epstein, J. B., Harris, L. D., 1977, Conodont color alteration—an index to organic metamorphism: U., S. Geological Survey Professional Paper 995, p. 1–27.</ref> and conodont alteration values are calibrated to the vitrinite reflectance scale. The use of ostracodes<ref name=ch17r1>Ainsworth, N., R., Burnett, R., D., Kontrovitz, M., 1990, Ostracod colour change by thermal alteration, offshore Ireland and Western UK: Marine and Petroleum Geology, vol. 7, p. 288–297., 10., 1016/0264-8172(90)90006-3</ref> and foraminifera<ref name=ch17r64>McNeil, D., H., Issler, D., R., 1992, Correlation of foraminiferal coloration (FCI) and time-temperature (TTI) indices from Beaufort Sea exploration data: AAPG Annual Convention Abstracts, p. 87.</ref> is a newly emerging approach and is not yet calibrated to vitrinite reflectance standards. The potential of these fossils is important because they commonly occur in lithologies devoid of organic-walled fossil remains (e.g., limestones, dolomites, fine-grained sands).
+
Fossils composed of phosphate ([[conodont]]s), carbonate ([[ostracod]]s), and agglutinated grains (agglutinated [[foraminifera]]) are also used for geothermometry. The organic framework of these fossils responds to thermal stress with color change. Of these, conodonts ([[conodont alteration index]], or CAI) are the most widely used<ref name=ch17r37>Epstein, A. G., Epstein, J. B., Harris, L. D., 1977, Conodont color alteration—an index to organic metamorphism: U., S. Geological Survey Professional Paper 995, p. 1–27.</ref> and conodont alteration values are calibrated to the vitrinite reflectance scale. The use of ostracods<ref name=ch17r1>Ainsworth, N., R., Burnett, R., D., Kontrovitz, M., 1990, Ostracod colour change by thermal alteration, offshore Ireland and Western UK: Marine and Petroleum Geology, vol. 7, p. 288–297, DOI: 10.1016/0264-8172(90)90006-3</ref> and foraminifera<ref name=ch17r64>McNeil, D., H., Issler, D., R., 1992, Correlation of foraminiferal coloration (FCI) and time-temperature (TTI) indices from Beaufort Sea exploration data: AAPG Annual Convention Abstracts, p. 87.</ref> is a newly emerging approach and is not yet calibrated to vitrinite reflectance standards. The potential of these fossils is important because they commonly occur in lithologies devoid of organic-walled fossil remains (e.g., limestones, dolomites, fine-grained sands).
  
 
==Whole kerogen analysis==
 
==Whole kerogen analysis==
Geochemists use a wide variety of organic compounds, derived from both terrestrial (land and aquatic) and marine organisms, to determine depositional environments and thermal maturation. These analyses assay whole kerogen assemblages and include elemental analyses (gas chromatography–mass spectrometry, or GC-MS), Fourier transform infrared spectroscopy (FTIR), biomarkers, spectral fluorescence, and Rock-Eval pyrolysis.
+
Geochemists use a wide variety of organic compounds, derived from both terrestrial (land and aquatic) and marine organisms, to determine depositional environments and thermal maturation. These analyses assay whole kerogen assemblages and include elemental analyses ([[gas chromatography–mass spectrometry]], or GC-MS), [[Fourier transform infrared spectroscopy]] (FTIR), biomarkers, spectral fluorescence, and [[Rock-Eval pyrolysis]].
  
 
==Use of multiple techniques==
 
==Use of multiple techniques==
Since none of these techniques is infallible in quantifying thermal maturation history for all conditions, two or more should be used when possible as a cross-check of the maturation data.<ref name=ch17r66>Nuccio, V., F., 1991, Combining methods yields best source rock maturity: World Oil, vol. 212, no. 9, p. 63–72.</ref> Caution is necessary, however, when equating thermal values to petroleum generation windows because different organic materials generate at different times during thermal exposure (e.g., early generators vs. late generators). This affects transformation ratios used in hydrocarbon systems modeling.
+
Since none of these techniques is infallible in quantifying thermal maturation history for all conditions, two or more should be used when possible as a cross-check of the maturation data.<ref name=ch17r66>Nuccio, V., F., 1991, Combining methods yields best source rock maturity: World Oil, vol. 212, no. 9, p. 63–72.</ref> Caution is necessary, however, when equating thermal values to [[petroleum generation]] windows because different organic materials generate at different times during thermal exposure (e.g., early generators vs. late generators). This affects transformation ratios used in hydrocarbon systems modeling.
  
 
==See also==
 
==See also==
* [[Applications]]
+
* [[Applications of biostratigraphy]]
 
* [[Biostratigraphic correlation and age determination]]
 
* [[Biostratigraphic correlation and age determination]]
 
* [[Paleoenvironmental analysis]]
 
* [[Paleoenvironmental analysis]]
Line 70: Line 72:
 
* [[Quantitative paleoenvironmental analysis]]
 
* [[Quantitative paleoenvironmental analysis]]
 
* [[Palynofacies and kerogen analysis]]
 
* [[Palynofacies and kerogen analysis]]
* [[Sequence stratigraphy]]
+
* [[Biostratigraphy in sequence stratigraphy]]
  
 
==References==
 
==References==
Line 82: Line 84:
 
[[Category:Predicting the occurrence of oil and gas traps]]  
 
[[Category:Predicting the occurrence of oil and gas traps]]  
 
[[Category:Applied paleontology]]
 
[[Category:Applied paleontology]]
 +
[[Category:Treatise Handbook 3]]

Latest revision as of 18:10, 24 January 2022

Exploring for Oil and Gas Traps
Series Treatise in Petroleum Geology
Part Predicting the occurrence of oil and gas traps
Chapter Applied paleontology
Author Robert L. Fleisher, H. Richard Lane
Link Web page
Store AAPG Store

Thermal maturity is the extent of heat-driven reactions that alter the composition of organic matter (e.g., conversion of sedimentary organic matter to petroleum or cracking of oil to gas.) Different geochemical scales, such as vitrinite reflectance, pyrolysis Tmax, and biomarker maturity ratios can be used to indicate the level of thermal maturity of organic matter.[1]

Many of the elements of basin modeling programs—maturation of source rocks, reservoir diagenesis, and porosity evolution—are affected by thermal and burial history.[2][3] Thermal maturation data used to model these parameters are usually derived from fossils.

The following table shows which fossil material changes appearance due to thermal stress and therefore can be used as organic geothermometers.

Fossil Material Thermal Maturation Scale
Vitrinite Vitrinite reflectance (Vr or Ro )
Pollen and spores Thermal Alteration Index (TAI)
Ostracods Ostracod Alteration Index (OAI)
Conodonts Conodont Alteration Index (CAI)
Foraminifera Foraminifera Alteration Index (FAI)
Graptolites Calibrated to Ro scale
Scolecodonts Calibrated to Ro scale
Chitinozoans Calibrated to Ro scale

Vitrinite[edit]

Vitrinite is a coaly organic maceral derived from the connective tissue of vascular plants. The reflectance of vitrinite changes with heat. Vitrinite reflectance (Vr or Ro), the most commonly used thermal indicator, is the benchmark for maturation studies in the petroleum and coal industries.[4] This technique is primarily useful for Devonian and younger clastic sediments and coals.

Pollen and spores[edit]

Pollen and spores are the organic-walled microfossils most commonly used for gauging paleotemperature. Fossil color, which changes with heating, is used to estimate a thermal alteration index, or TAI.[5][6][7] The use of pollen and spores lets us examine in situ fossils rather than evaluate an aggregate “kerogen soup.” Other organic-walled fossils—acritarchs, chitinozoans, graptolites, scolecodonts (annelid worm jaws), and dinoflagellates—have been examined for their visual and reflected values, but these fossil groups have not been rigorously calibrated to the standard vitrinite reflectance scale.[8]

Other microfossils[edit]

Fossils composed of phosphate (conodonts), carbonate (ostracods), and agglutinated grains (agglutinated foraminifera) are also used for geothermometry. The organic framework of these fossils responds to thermal stress with color change. Of these, conodonts (conodont alteration index, or CAI) are the most widely used[9] and conodont alteration values are calibrated to the vitrinite reflectance scale. The use of ostracods[10] and foraminifera[11] is a newly emerging approach and is not yet calibrated to vitrinite reflectance standards. The potential of these fossils is important because they commonly occur in lithologies devoid of organic-walled fossil remains (e.g., limestones, dolomites, fine-grained sands).

Whole kerogen analysis[edit]

Geochemists use a wide variety of organic compounds, derived from both terrestrial (land and aquatic) and marine organisms, to determine depositional environments and thermal maturation. These analyses assay whole kerogen assemblages and include elemental analyses (gas chromatography–mass spectrometry, or GC-MS), Fourier transform infrared spectroscopy (FTIR), biomarkers, spectral fluorescence, and Rock-Eval pyrolysis.

Use of multiple techniques[edit]

Since none of these techniques is infallible in quantifying thermal maturation history for all conditions, two or more should be used when possible as a cross-check of the maturation data.[12] Caution is necessary, however, when equating thermal values to petroleum generation windows because different organic materials generate at different times during thermal exposure (e.g., early generators vs. late generators). This affects transformation ratios used in hydrocarbon systems modeling.

See also[edit]

References[edit]

  1. Peters, Kenneth E., David J. Curry, and Marek Kacewicz, 2012, An overview of basin and petroleum system modeling: Definitions and concepts, in Peters, Kenneth E., David J. Curry, and Marek Kacewicz, eds., Basin modeling: New horizons in research and applications: AAPG Hedberg Series no. 4, p. 1-16.
  2. van Gizjel, P., 1980, Characterization and identification of kerogen and bitumen and determination of thermal maturation by means of qualitative and quantitative microscopical techniques, in How to Assess Maturation and Paleotemperatures: SEPM Short Course Notes, p. 1–56.
  3. Pradier, B., Bertrand, P., Martinez, L., Laggoun-Defarge, F., 1991, Fluorescence of organic matter and thermal maturity assessment: Organic Geochemistry, vol. 17, no. 4, p. 511–524, DOI: 10.1016/0146-6380(91)90115-Z.
  4. Dow, W., G., O'Connor, D., I., 1982, Kerogen maturity and type by reflected light microscopy applied to petroleum generation, in How To Assess Maturation and Paleotemperatures: SEPM Short Course Notes, p. 79–99.
  5. Staplin, F., L., 1969, Sedimentary organic matter, organic metamorphism, and oil and gas occurrence: Bulletin of Canadian Petroleum Geology, vol. 17, no. 1, p. 47–66.
  6. Lerche, I., McKenna, T., C., 1991, Pollen translucency as a thermal maturation indicator: Journal of Petroleum Geology, vol. 14, no. 1, p. 19–36, DOI: 10.1111/jpg.1991.14.issue-1
  7. Marshall, J., E., A., 1991, Quantitative spore colour: Journal of the Geological Society of London, vol. 148, p. 223–233, DOI: 10.1144/gsjgs.148.2.0223
  8. Bertrand, R., Heroux, Y., 1987, Chitinozoan, graptolite and scolecodont reflectance as an alternative to vitrinite and pyrobitumen reflectance in Ordovician and Silurian strata, Anticosti Island, Quebec, Canada: AAPG Bulletin, vol. 41, p. 951–957.
  9. Epstein, A. G., Epstein, J. B., Harris, L. D., 1977, Conodont color alteration—an index to organic metamorphism: U., S. Geological Survey Professional Paper 995, p. 1–27.
  10. Ainsworth, N., R., Burnett, R., D., Kontrovitz, M., 1990, Ostracod colour change by thermal alteration, offshore Ireland and Western UK: Marine and Petroleum Geology, vol. 7, p. 288–297, DOI: 10.1016/0264-8172(90)90006-3
  11. McNeil, D., H., Issler, D., R., 1992, Correlation of foraminiferal coloration (FCI) and time-temperature (TTI) indices from Beaufort Sea exploration data: AAPG Annual Convention Abstracts, p. 87.
  12. Nuccio, V., F., 1991, Combining methods yields best source rock maturity: World Oil, vol. 212, no. 9, p. 63–72.

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