1,705
edits
Changes
Jump to navigation
Jump to search
Pyrolysis gas chromatography (view source)
Revision as of 13:38, 24 January 2014
, 13:38, 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
}}
==What is Py-GC?==
Pyrolysis gas chromatography (Py-GC) is anhydrous thermal decomposition of a material that leads to the conversion of kerogen to hydrocarbon compounds. Py-GC can be conducted on whole rock or isolated kerogen samples to obtain a visual signature or “fingerprint” of the organic material present.
==How to read gas chromatograms==
Gas chromatography generally is a qualitative tool. It is not typically used as a quantitative measurement of hydrocarbon molecules. However, the patterns generated in the chromatograms can help us determine if a source rock will be oil or gas prone.
The X-axis of a gas chromatogram is retention time, and the Y-axis is the relative quantity of each compound. Each spike in the chromatogram represents a particular hydrocarbon compound, beginning with lowest number of carbon atoms in the compound on the left and going to higher chains of carbons to the right. The height of the spike represents the relative abundance of the compound pyrolized from the sample's kerogen. Typical gas chromatogram examples for types I, II, and III kerogen are shown below.
[[file:evaluating-source-rocks_fig6-5.png|thumb|{{figure number|6-5}}See text for explanation.]]
==Interpreting gas chromatograms==
A gas chromatogram is evaluated qualitatively to determine the potential of a rock to generate oil vs. gas. The table below shows how chromatograms for oil- vs. gas-prone rocks are evaluated.
{| class = "wikitable"
|-
! Chromatograms of oil-prone rock
! Chromatograms of gas-prone rock
|-
| Dominated by long-chain carbon compounds (greater than C<sub>10</sub> )
| Dominated by short-chain carbon compounds from C<sub>1</sub> –C<sub>4</sub>
|-
| Contain carbon compounds up to C<sub>25</sub> or greater
| Contain very few carbon compounds above C<sub>10</sub>
|}
==See also==
* [[Evaluating source rock quality]]
* [[Kerogen types]]
* [[Evaluating quality using rock-eval HI/OI]]
* [[Visually assessing quality]]
==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
}}
==What is Py-GC?==
Pyrolysis gas chromatography (Py-GC) is anhydrous thermal decomposition of a material that leads to the conversion of kerogen to hydrocarbon compounds. Py-GC can be conducted on whole rock or isolated kerogen samples to obtain a visual signature or “fingerprint” of the organic material present.
==How to read gas chromatograms==
Gas chromatography generally is a qualitative tool. It is not typically used as a quantitative measurement of hydrocarbon molecules. However, the patterns generated in the chromatograms can help us determine if a source rock will be oil or gas prone.
The X-axis of a gas chromatogram is retention time, and the Y-axis is the relative quantity of each compound. Each spike in the chromatogram represents a particular hydrocarbon compound, beginning with lowest number of carbon atoms in the compound on the left and going to higher chains of carbons to the right. The height of the spike represents the relative abundance of the compound pyrolized from the sample's kerogen. Typical gas chromatogram examples for types I, II, and III kerogen are shown below.
[[file:evaluating-source-rocks_fig6-5.png|thumb|{{figure number|6-5}}See text for explanation.]]
==Interpreting gas chromatograms==
A gas chromatogram is evaluated qualitatively to determine the potential of a rock to generate oil vs. gas. The table below shows how chromatograms for oil- vs. gas-prone rocks are evaluated.
{| class = "wikitable"
|-
! Chromatograms of oil-prone rock
! Chromatograms of gas-prone rock
|-
| Dominated by long-chain carbon compounds (greater than C<sub>10</sub> )
| Dominated by short-chain carbon compounds from C<sub>1</sub> –C<sub>4</sub>
|-
| Contain carbon compounds up to C<sub>25</sub> or greater
| Contain very few carbon compounds above C<sub>10</sub>
|}
==See also==
* [[Evaluating source rock quality]]
* [[Kerogen types]]
* [[Evaluating quality using rock-eval HI/OI]]
* [[Visually assessing quality]]
==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]]