The comparison of biomarkers released by hydropyrolysis and Soxhlet extraction from source rocks of different maturities

The Permian Dalong Formation(P2d) source rocks from the mature Guangyuan outcrop section and the overmature Wangcang outcrop section in Sichuan Basin were selected.The Soxhlet extraction and kerogen catalytic HyPy were conducted on the P2d source rocks.The biomarkers obtained by both methods were compared to discuss their difference and the influence extent of thermal maturation on covalently bound biomarkers.The results show that covalently bound biomarkers can hardly be correlated to the corresponding free biomarkers due to severe thermal alterations and/or interference of migrated hydrocarbons in both outcrop sections and thermal maturation have much lower influence on covalently bound biomarkers in kerogens than on free biomarkers in Soxhlet extracts.The application of HyPy in study of biomarker geochemistry can reduce the thermal maturation effect on biomarkers(Ro≤2.4%) to a greater extent and the interference of migrated hydrocarbons between interbedded layers.The covalently bound biomarkers released by HyPy are useful in the study of biomarker geochemistry and oil-source correlation on high-overmature source rocks.