Several families of thiophenic organosulfur compounds (primarily benzoand dibenzothiophenes) show promise for distinguishing oils derived from carbonate sources versus siliciclastic sources. This observation is based on analyses, using high-resolution gas chromatography coupled with a flame photometric detector, of several representative oils derived from carbonate sources (Smackover and Sunniland Formations, southeastern United States; Burgan and Minagish, Kuwait; and the Khatiyah Formation, Dubai) and, for comparison, of oils from silicilastic sources commonly show low concentrations of benzothiophenes, decreasing amounts of dibenzothiophenes, and a different pattern in methyldibenzothiophene isomers.

The distinguishing features of carbonate-derived oils are applicable through the main phase of oil generation. Additional thermal maturity results in a significant reduction in the amounts of benzothiophenes and a redistribution of methyldibenzothiophene isomers, making the differences between carbonate- and siliciclastic-derived oils less distinctive. However, in these cases the distribution of mono-, di-, and trimethyl substituted dibenzothiophenes is generally relatively uniform in carbonate oils, while siliciclastic oils show decreasing amounts of dimethyl- and trimethyldibenzothiophenes relative to methyldibenzothiophenes.

Used in conjunction with such other geochemical parameters as total sulfur content, n-alkane compositions, and sterane/triterpane compositions, thiophenic organosulfur analysis provides a useful tool for oil-oil and oil-source-rock correlations as exemplified by a study of 20 oils from the Salawati basin, Indonesia.