Crude oil samples were separated into the saturated and aromatic hydrocarbon fractions using column chromatography. The relative proportions of saturated, aromatic and NSO compounds are presented in oils.
Thank you very much my dear Dr. Rzger for the important information, best regards
No. The use of Aro/Sat ratios in crude oils is more related to determination of source, thermal maturity, and biodegradation.
I don't think so. This ratio is a very rough data which has not any age dependance for it is dependant on may factors: origin, migration, biodegradation , oxydation, water washing , etc.
Best
w
I agree with the above, regarding the interpretation of source rock age and the utility of saturate/aromatic fration data. I would like to comment on Jacques' response regarding water washing. It is, the interpretation of me and others, that water washing is a dubious process. Thompson definded water washing in his benchmark paper based on the variaton of gasoline range aromatic compounds, toluene and benzene. The recently deceased Wally Dow had given Thompson Williston Basin samples for his study and Thompson noticed a continuous varation of the concentration of benzene and toluene relative to similar carbon number alkanes in th gasolie range fraction of Dow's Type II oils. Discounting source Thompson was aware of the much higher solubility of the aromatic compounds n water compared to alkanes. He interpreted the observed variations to be attribtable to "water-washing". Subseqent work by myself and others showed that Dow's Type II oils were in fact two distinctive oil families with different sources in the Bakken (clastic-low gasoline range aromatics and low sulphur kerogen) and overlying Lodgepole (carbonate-abundant gasoline range aromatics and high sulphur kerogen) formations and that the compositional variations in gasoline range aromatic compounds results from differential mixing of these two different oil families (see Org. Geochem. 2004, v. 35, p. 453-468, especially referenes therein and Figure 4). While selective compositional changes are attributed to petroleum-water interactions (e.g. benzocarbazoles, see Larter et al., Nature. 1996, v. 383, p 53-7.) in other cases it is dubious if gasoline range compositional alteration by water washing as originally defined by Thompson is an actual process.
Please, correct me if I am wrong. I think that saturate/aromatic ratio can provide clues of thermal maturity.
Saturate/aromatic ratio not only gives information about the thermal maturity of oils, it also gives an idea about the asphaltene content of oils e.g. an oil with a low saturate/aromatic ratio most likely has a high asphaltene contant and vice versa; this helps in estimating potential problems posed to the refinery by such oil.
TSR has devastating effects on this ratio. SO that, saturate HCs consume more rapidly by this phenomena. Reservoirs in contiguous to evaporates which buried more deeply are more susceptible for occurrences of this event.
As elaborated above by several colleagues, SAT/ARO ratio might qualitatively be used for thermal maturation determination and recognition of type of organic matter input. For age determination, age-specific biomarkers like Oleanane is frequently used.
Hello Umar,
No, it cannot be used to infer age. It can be used to infer maturity as others have pointed out and for qualitative indication of biodegradation.
Hi Saeed Mohammed , I never said it can be used for age determination!
Hello Omer,
I was responding to the question posed by Amer Jassim. My response was meant for hm. My apologies that the response was addressed to you.
Regards,
Saeed
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