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Line 25: + + + − The figure below shows an example of a correlation between an oil and a condensate using δ<sup>13</sup>C values for individual C<sub>10</sub> – C<sub>27</sub> ''n''-alkanes. These two samples are from a single oil field on the U.S. Gulf Coast. The condensate does not contain measurable ''n''-alkanes beyond ''n-''C<sub>18</sub>, rendering biomarker techniques of little value. The similarity in ''n''-alkane δ<sup>13</sup>C values for these two samples supports the conclusion that they are sourced from similar organic facies.+ − − [[file:oiloil-and-oilsource-rock-correlations_fig8-4.png|thumb|{{figure number|8-4}}. Copyright: Unocal.]]
Isotopic parameter data for oil–oil and oil–source rock correlations (view source)
Revision as of 17:48, 11 February 2014
, 17:48, 11 February 2014→Compound-specific isotope analysis
==Compound-specific isotope analysis==
==Compound-specific isotope analysis==
[[file:oiloil-and-oilsource-rock-correlations_fig8-4.png|thumb|{{figure number|2}}. Copyright: Unocal.]]
Over the last decade, much interest has developed in compound-specific isotope analysis, in which carbon isotope ratios are measured for numerous individual compounds in a sample and then plotted to give a fingerprint.
Over the last decade, much interest has developed in compound-specific isotope analysis, in which carbon isotope ratios are measured for numerous individual compounds in a sample and then plotted to give a fingerprint.
In addition to ''n''-alkanes, isotope ratios have been measured for pristane, phytane, and other biomarkers.<ref name=ch08r1>Bjorøy, M., Hall, K., Gillyon, P., Jumeau, J., 1991, Carbon isotope variations in n-alkanes and isoprenoids of whole oils: Chemical Geology, vol. 93, p. 13–20., 10., 1016/0009-2541(91)90061-U</ref><ref name=ch08r6>Clayton, C., J., Bjorøy, M., 1994, Effect of maturity on 13C/12C ratios of individual compounds in North Sea oils: Organic Geochemistry, vol. 21, p. 737–750., 10., 1016/0146-6380(94)90016-7</ref> Although this technique is highly promising for correlations, initial attempts to interpret the data suggest that additional research to identify causes for isotopic variations will be necessary before the technique can be applied routinely and with confidence.
In addition to ''n''-alkanes, isotope ratios have been measured for pristane, phytane, and other biomarkers.<ref name=ch08r1>Bjorøy, M., Hall, K., Gillyon, P., Jumeau, J., 1991, Carbon isotope variations in n-alkanes and isoprenoids of whole oils: Chemical Geology, vol. 93, p. 13–20., 10., 1016/0009-2541(91)90061-U</ref><ref name=ch08r6>Clayton, C., J., Bjorøy, M., 1994, Effect of maturity on 13C/12C ratios of individual compounds in North Sea oils: Organic Geochemistry, vol. 21, p. 737–750., 10., 1016/0146-6380(94)90016-7</ref> Although this technique is highly promising for correlations, initial attempts to interpret the data suggest that additional research to identify causes for isotopic variations will be necessary before the technique can be applied routinely and with confidence.
[[:file:oiloil-and-oilsource-rock-correlations_fig8-4.png|Figure 2]] shows an example of a correlation between an oil and a condensate using δ<sup>13</sup>C values for individual C<sub>10</sub> – C<sub>27</sub> ''n''-alkanes. These two samples are from a single oil field on the U.S. Gulf Coast. The condensate does not contain measurable ''n''-alkanes beyond ''n-''C<sub>18</sub>, rendering biomarker techniques of little value. The similarity in ''n''-alkane δ<sup>13</sup>C values for these two samples supports the conclusion that they are sourced from similar organic facies.
==Sulfur and hydrogen isotopes==
==Sulfur and hydrogen isotopes==