AN INTEGRATED LIGHT HYDROCARBON GUIDED CHARACTERIZATION OF SULFUR-RICH CARBONATE SOURCED HYDROCARBONS

Sulfur-rich carbonate sourced oils comprise a complex geochemistry related to the petroleum system from where they were generated, expelled, and eventually trapped and stored in a reservoir. During their migration to the reservoir, they often mix with other generated oils from diverse organofacies within the petroleum system and undergo secondary alteration which can change their original thiophene geochemical fingerprint. Therefore, it is a challenge to employ and interpret biomarkers and traditional ancillary compounds from these hydrocarbons to effectively separate source chemistry from that caused by secondary alteration processes without some guidance. Recent work on the characterization of a limited number of sulfur-rich hydrocarbon samples demonstrates the thermal and chemical stability of the isoheptane chemistry from these oils can prove valuable for guiding this process when only a small number of samples are available to evaluate. Presented is an integrated characterization of five hydrocarbon samples where the isoheptane and C₇ light hydrocarbon chemistry is used to guide the interpretation of biomarkers, ancillary compounds, diamondoids, and trace element chemistry to explain the anomalous bulk chemistry and densities observed which differs from what is expected from their maturity. The results provide insight into the challenges that arise during initial determinations of the original provenance for oils within a petroleum system where bulk chemistry versus densities have been significantly altered by secondary processes.