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Line 93: − The figure below shows a gas chromatogram of saturated hydrocarbons in a source rock extract from which the extracting solvent was evaporated too vigorously, leading to loss of some of the C<sub>15+</sub> fraction. This problem can be recognized by looking at the ''n''-C<sub>17</sub> and ''n''-C<sub>18</sub> peaks. Normally they are almost the same size, but in this case the ''n''-C<sub>17</sub> peak is much smaller. Pristane has also been depleted relative to phytane, leading to an erroneous pristane–phytane ratio unless some correction is made. − + + + − The figure below shows a gas chromatogram of an oil whose light ends were partially removed during gas stripping in the reservoir. Oils like this one are often observed in deep reservoirs in Tertiary deltaic sequences. − + + +
Gas chromatography: data obtained (view source)
Revision as of 14:43, 4 February 2014
, 14:43, 4 February 2014→Example of loss of C15+ fraction
==Example of loss of C<sub>15+</sub> fraction==
==Example of loss of C<sub>15+</sub> fraction==
[[file:oiloil-and-oilsource-rock-correlations_fig8-15.png|thumb|{{figure number|8-15}}. Copyright: Unocal.]]
[[file:oiloil-and-oilsource-rock-correlations_fig8-15.png|left|thumb|{{figure number|11}}. Copyright: Unocal.]]
[[:file:oiloil-and-oilsource-rock-correlations_fig8-15.png|Figure 11]] shows a gas chromatogram of saturated hydrocarbons in a source rock extract from which the extracting solvent was evaporated too vigorously, leading to loss of some of the C<sub>15+</sub> fraction. This problem can be recognized by looking at the ''n''-C<sub>17</sub> and ''n''-C<sub>18</sub> peaks. Normally they are almost the same size, but in this case the ''n''-C<sub>17</sub> peak is much smaller. Pristane has also been depleted relative to phytane, leading to an erroneous pristane–phytane ratio unless some correction is made.
===Example of loss of light ends===
===Example of loss of light ends===
[[file:oiloil-and-oilsource-rock-correlations_fig8-16.png|thumb|{{figure number|8-16}}. Copyright: Unocal.]]
[[file:oiloil-and-oilsource-rock-correlations_fig8-16.png|thumb|{{figure number|12}}. Copyright: Unocal.]]
[[:file:oiloil-and-oilsource-rock-correlations_fig8-16.png|Figure 12]] shows a gas chromatogram of an oil whose light ends were partially removed during gas stripping in the reservoir. Oils like this one are often observed in deep reservoirs in Tertiary deltaic sequences.
==Limitations due to internal standards==
==Limitations due to internal standards==