Abstract:  Trace compounds are important indicators for the study of petroleum genesis, source, formation environment, secondary geochemical alterations, etc. Trace compounds are playing a much more important role in petroleum geochemistry studies as research interests continue to advance to unconventional and deep reservoirs recently. This paper has reviewed the definition and classification of trace compounds in crude oil and their research progress in the analysis of organic material source and formation environment, oil/gas maturity and oilsource correlation at higher maturation stage, tracing of oil/gas migration pathways, and secondary geochemical alteration on oil/gas in recent years. The application of trace compoundsbased evaluation parameters for the thermal cracking degree of crude oil, thermochemical sulfate reduction, and gas invasion alterations has also been summarized. It is also proposed that future research will focus on the formation mechanism of trace compounds, the identification of sourceindicative trace compounds, and the strengthening of compoundspecific isotope analysis. With the continuous improvement of analytical technology and research understanding, potential new compounds in transitional state may be discovered.

Key words:  , crude oil, trace compounds, organic material source, oilsource correlation, migration pathway tracing, secondary alteration on oil/gas