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Kerogen type and hydrocarbon generation (view source)
Revision as of 13:53, 24 January 2014
, 13:53, 24 January 2014Initial import
{{publication
| image = exploring-for-oil-and-gas-traps.png
| width = 120px
| series = Treatise in Petroleum Geology
| title = Exploring for Oil and Gas Traps
| part = Critical elements of the petroleum system
| chapter = Evaluating source rocks
| frompg = 6-1
| topg = 6-41
| author = Carol A. Law
| link = http://archives.datapages.com/data/specpubs/beaumont/ch06/ch06.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
Kerogen consists of many fractions, each converting to hydrocarbons at a specified rate. This rate of conversion to hydrocarbons is defined by a first-order rate equation known as the Arrhenius law:
:<math>\mbox{K}({+}) = \mbox{A}_{\rm e}^{-{\rm E/RT(t)}}</math>
where:
* A = Arrhenius factor
* E = activation energy
These are generally referred to as '''kinetic parameters'''. They can be measured using various pyrolysis techniques and are different for each distinct kerogen analyzed.
==Hydrocarbon generation—depth and yield==
The depth of hydrocarbon generation and the yield of individual hydrocarbon phases are primarily a function of the kinetics of the kerogen-hydrocarbon conversion. Burial history and catalytic effects, due to source rock matrix chemistry, affect the rate of generation, although these effects are secondary to the kinetic effects.
The following hydrocarbon generation vs. depth plots for types I (left) and III (right) kerogens are based on identical burial and thermal conditions. Thus, they depict the difference in the depth of hydrocarbon generation, based on kerogen type alone. Type I kerogen generally has a shallower liquid hydrocarbon zone and generates significantly larger amounts of hydrocarbons. The onset of generation is indicated by the change in the slope of the curves.
[[file:evaluating-source-rocks_fig6-15.png|thumb|{{figure number|6-15}}. Copyright: results of Genex 1-D basin [[modeling]] software, courtesy Institute Français du Petrole.]]
==Timing hydrocarbon generation==
Variations in the kinetic parameters affect predictions of the present-day distribution of hydrocarbon generation zones and also influence when, in geologic time, a potential source interval generates. The figures below compare the timing of hydrocarbon generation from type I kerogen (left) to type III (right). The onset of hydrocarbon generation is indicated by the dramatic change in slope of the curves: 110-100 Ma for type I and 90-80 Ma for type III. The difference in timing shown in this example is based only on the different kinetic parameters of the kerogen types.
[[file:evaluating-source-rocks_fig6-16.png|thumb|{{figure number|6-16}}See text for explanation.]]
==Recommendations==
Conduct kerogen kinetic analysis on samples from the basin being modeled. If samples are not available, standard values for types I–III are available from ;<ref name=ch06r1>Burnham, A., K., 1989, A Simple Model of Petroleum Formation and Cracking: Lawrence Livermore Laboratory report UCID 21665, March 1989. Basic review of the kinetic conversion of kerogens to hydrocarbons.</ref><ref name=ch06r2>Burnham, A., K., Sweeney, J., J., 1990, [[Modeling]] Maturation and Migration of Petroleum: Lawrence Livermore Laboratory report UCRL 102602, rev. 1. The kinetics of kerogen conversion are presented and discussed relative to the prediction of hydrocarbon generation and occurrence.</ref> and .<ref name=ch06r11>Tissot, B., P., Espitalie, J., 1975, L'evolution thermique de la matiere organique des sediments: aplications d'une simulation mathematique: Rev. IFP, vol. 30, p. 743–777. In French. Contains basic IFP kerogen kinetic data., 10., 2516/ogst:1975026</ref> Apply these values after carefully classifying the kerogen type in terms of the depositional environment of the individual source intervals.
==See also==
* [[Relationships between maturity and hydrocarbon generation]]
* [[Kerogen type and maturity]]
* [[Kerogen type and transformation ratio]]
* [[Comparison of kerogen types]]
* [[Open-vs. Closed-system generation modeling]]
==References==
{{reflist}}
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch06/ch06.htm Original content in Datapages]
* [http://store.aapg.org/detail.aspx?id=545 Find the book in the AAPG Store]
[[Category:Critical elements of the petroleum system]]
[[Category:Evaluating source rocks]]
| image = exploring-for-oil-and-gas-traps.png
| width = 120px
| series = Treatise in Petroleum Geology
| title = Exploring for Oil and Gas Traps
| part = Critical elements of the petroleum system
| chapter = Evaluating source rocks
| frompg = 6-1
| topg = 6-41
| author = Carol A. Law
| link = http://archives.datapages.com/data/specpubs/beaumont/ch06/ch06.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
Kerogen consists of many fractions, each converting to hydrocarbons at a specified rate. This rate of conversion to hydrocarbons is defined by a first-order rate equation known as the Arrhenius law:
:<math>\mbox{K}({+}) = \mbox{A}_{\rm e}^{-{\rm E/RT(t)}}</math>
where:
* A = Arrhenius factor
* E = activation energy
These are generally referred to as '''kinetic parameters'''. They can be measured using various pyrolysis techniques and are different for each distinct kerogen analyzed.
==Hydrocarbon generation—depth and yield==
The depth of hydrocarbon generation and the yield of individual hydrocarbon phases are primarily a function of the kinetics of the kerogen-hydrocarbon conversion. Burial history and catalytic effects, due to source rock matrix chemistry, affect the rate of generation, although these effects are secondary to the kinetic effects.
The following hydrocarbon generation vs. depth plots for types I (left) and III (right) kerogens are based on identical burial and thermal conditions. Thus, they depict the difference in the depth of hydrocarbon generation, based on kerogen type alone. Type I kerogen generally has a shallower liquid hydrocarbon zone and generates significantly larger amounts of hydrocarbons. The onset of generation is indicated by the change in the slope of the curves.
[[file:evaluating-source-rocks_fig6-15.png|thumb|{{figure number|6-15}}. Copyright: results of Genex 1-D basin [[modeling]] software, courtesy Institute Français du Petrole.]]
==Timing hydrocarbon generation==
Variations in the kinetic parameters affect predictions of the present-day distribution of hydrocarbon generation zones and also influence when, in geologic time, a potential source interval generates. The figures below compare the timing of hydrocarbon generation from type I kerogen (left) to type III (right). The onset of hydrocarbon generation is indicated by the dramatic change in slope of the curves: 110-100 Ma for type I and 90-80 Ma for type III. The difference in timing shown in this example is based only on the different kinetic parameters of the kerogen types.
[[file:evaluating-source-rocks_fig6-16.png|thumb|{{figure number|6-16}}See text for explanation.]]
==Recommendations==
Conduct kerogen kinetic analysis on samples from the basin being modeled. If samples are not available, standard values for types I–III are available from ;<ref name=ch06r1>Burnham, A., K., 1989, A Simple Model of Petroleum Formation and Cracking: Lawrence Livermore Laboratory report UCID 21665, March 1989. Basic review of the kinetic conversion of kerogens to hydrocarbons.</ref><ref name=ch06r2>Burnham, A., K., Sweeney, J., J., 1990, [[Modeling]] Maturation and Migration of Petroleum: Lawrence Livermore Laboratory report UCRL 102602, rev. 1. The kinetics of kerogen conversion are presented and discussed relative to the prediction of hydrocarbon generation and occurrence.</ref> and .<ref name=ch06r11>Tissot, B., P., Espitalie, J., 1975, L'evolution thermique de la matiere organique des sediments: aplications d'une simulation mathematique: Rev. IFP, vol. 30, p. 743–777. In French. Contains basic IFP kerogen kinetic data., 10., 2516/ogst:1975026</ref> Apply these values after carefully classifying the kerogen type in terms of the depositional environment of the individual source intervals.
==See also==
* [[Relationships between maturity and hydrocarbon generation]]
* [[Kerogen type and maturity]]
* [[Kerogen type and transformation ratio]]
* [[Comparison of kerogen types]]
* [[Open-vs. Closed-system generation modeling]]
==References==
{{reflist}}
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch06/ch06.htm Original content in Datapages]
* [http://store.aapg.org/detail.aspx?id=545 Find the book in the AAPG Store]
[[Category:Critical elements of the petroleum system]]
[[Category:Evaluating source rocks]]