Changes

==Limitations due to evaporative loss==

==Limitations due to evaporative loss==

Evaporative loss can affect the appearance of gas chromatograms. When the solvent is removed too fast during recovery of source rock extracts, selective loss of some of the C₁₅₊ components can occur. This loss not only alters the appearance of the gas chromatograms but may also change compound ratios (for example, the [[pristane-phytane ratio]] through selective loss of pristane). In some instances, gas stripping in the reservoir can selectively remove lighter components, leaving an oil or residue that looks lightly [http://www.oiltracers.com/services/exploration-geochemistry/oil-biodegradation.aspx biodegraded] or, in some instances, waxy.

Evaporative loss can affect the appearance of gas chromatograms. When the solvent is removed too fast during recovery of source rock extracts, selective loss of some of the C₁₅₊ components can occur. This loss not only alters the appearance of the gas chromatograms but may also change compound ratios (for example, the [[pristane-phytane ratio]] through selective loss of pristane). In some instances, [http://www.gazprominfo.com/terms/topping-gas/ gas stripping] in the reservoir can selectively remove lighter components, leaving an oil or residue that looks lightly [http://www.oiltracers.com/services/exploration-geochemistry/oil-biodegradation.aspx biodegraded] or, in some instances, waxy.

==Example of loss of C₁₅₊ fraction==

==Example of loss of C₁₅₊ fraction==

===Example of loss of light ends===

===Example of loss of light ends===

[[: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.

[[: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 [http://www.gazprominfo.com/terms/topping-gas/ 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==