Genetic classification and geochemical evaluation of oil families in the South Dezful Embayment, southwest of Iran


1 Department of Geology, Faculty of Earth Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran

2 Exploration Directorate, National Iranian Oil Company (NIOC EXP), Tehran, Iran


The occurrence of barren anticlines in the vicinity of major hydrocarbon fields producing from individual ‎reservoirs in the south of the Dezful Embayment unveils the structural complexity of the area and the ‎intricacy of the processes of hydrocarbon generation, migration and entrapment. In this study, we ‎investigate the possible genetic relationships between the Jurassic-Lower Cretaceous reservoirs on one ‎hand, and the Upper Cretaceous-Tertiary reservoirs on the other. A comprehensive geochemical approach ‎is undertaken to identify genetic oil families in the study area and throw some light on the existing ‎petroleum systems. Bulk geochemical properties and molecular fingerprints support the existence of two ‎distinct oil families within the Khami Group (Jurassic-Lower Cretaceous) and the Asmari-Sarvak (Upper ‎Cretaceous-Tertiary) reservoirs. Source and maturity related biomarker parameters well suggest differing ‎source rocks for these oil families. Oils in the Asmari-Sarvak family indicate a uniform thermal maturity ‎equivalent to the middle oil window. These oils have originated from a marly-carbonate source rock with ‎mixed marine-terrigenous organic matter input that was deposited under anoxic to semi-anoxic ‎conditions. The oils in the Khami Group family are derived from an older Early Cretaceous source rock ‎deposited under dysoxic to semi-anoxic conditions that could receive significant inputs of terrigenous ‎organic matter. These oils are most likely generated at the peak of oil generation window from their ‎parent source rock. Data from this study suggest that the immature Pabdeh Formation is a subordinate ‎source rock of the Asmari-Sarvak oil family that could play a minor impregnating role.‎


Al-Husseini, M., 2008. Middle East geological time scale 2008: Cenozoic Era, Cretaceous and Jurassic Periods of Mesozoic Era. GeoArabia, 13 (4).
Alizadeh, B., Sarafdokht, H., Rajabi, M., Opera, A., Janbaz, M., 2012. Organic geochemistry and petrography of Kazhdumi (Albian–Cenomanian) and Pabdeh (Paleogene) potential source rocks in southern part of the Dezful Embayment, Iran. Organic geochemistry 49, 36-46.
Alsharhan, A., 2014. Petroleum systems in the Middle East. Geological Society, London, Special Publications 392, 361-408.
Baniasad, A., Rabbani, A.R., Moallemi, S.A., Soleimany, B., Rashidi, M., 2017. Petroleum system analysis of the northwestern part of the Persian Gulf, Iranian sector. Organic Geochemistry 107, 69-85.
Beydoun, Z., Clarke, M.H., Stoneley, R., 1992. Petroleum in the Zagros Basin: A Late Tertiary Foreland Basin Overprinted onto the Outer Edge of a Vast Hydrocarbon-Rich Paleozoic-Mesozoic Passive-Margin Shelf: Chapter 11.
Beydoun, Z.R., 1993. Evolution of the Northeastern Arabian Plate Margin and Shelf: Hydrocarbon Habitat and Conceptual Future Potential. Rev. Inst. Fr. Pét. 48, 311-345.
Bordenave, M., 2014. Petroleum systems and distribution of the oil and gas fields in the Iranian part of the Tethyan region. AAPG Memoir 106, 505-540.
Bordenave, M., Burwood, R., 1990. Source rock distribution and maturation in the Zagros orogenic belt: provenance of the Asmari and Bangestan reservoir oil accumulations. Organic Geochemistry 16, 369-387.
Bordenave, M., Hegre, J., 2005. The influence of tectonics on the entrapment of oil in the Dezful Embayment, Zagros Foldbelt, Iran. Journal of Petroleum Geology 28, 339-368.
Bordenave, M., Hegre, J., 2010. Current distribution of oil and gas fields in the Zagros Fold Belt of Iran and contiguous offshore as the result of the petroleum systems. Geological Society, London, Special Publications 330, 291-353.
Bordenave, M., Huc, A., 1995. The Cretaceous source rocks in the Zagros foothills of Iran. Revue de L'institut Français du Petrole 50, 727-752.
Cohen, K., Finney, S., Gibbard, P., Fan, J.-X., 2013. The ICS international chronostratigraphic chart. Episodes 36, 199-204.
Fard, I.A., Braathen, A., Mokhtari, M., Alavi, S.A., 2006. Interaction of the Zagros Fold-Thrust Belt and the Arabian-type, deep-seated folds in the Abadan Plain and the Dezful Embayment, SW Iran. Petroleum Geoscience 12, 347-362.
Grantham, P., Wakefield, L., 1988. Variations in the sterane carbon number distributions of marine source rock derived crude oils through geological time. Organic Geochemistry 12, 61-73.
Holba, A., Ellis, L., Dzou, I., Hallam, A., Masterson, W., Francu, J., Fincannon, A., 2001. Extended tricyclic terpanes as age discriminators between Triassic, Early Jurassic and Middle-Late Jurassic oils, 20th International Meeting on Organic Geochemistry. EAOG Nancy, France, p. 464.
Letouzey, J., Sherkati, S., 2004. Salt movement, tectonic events, and structural style in the central Zagros fold and thrust belt (Iran), Salt-sediment interactions and hydrocarbon prospectivity: 24th Annual Research Conference, Gulf Coast Section, SEPM Foundation, pp. 444-463.
Maghsoodi, M., 2001. Zagros Structures Index Map, 2001 ed. Geological Division, Exploration Directorate, National Iranian Oil Company, Tehran, Iran, p. Zagros Structural Index Map.
Murris, R., 1980. Middle East: stratigraphic evolution and oil habitat. AAPG Bulletin 64, 597-618.
Navabpour, P., Barrier, E., 2012. Stress states in the Zagros fold-and-thrust belt from passive margin to collisional tectonic setting. Tectonophysics 581, 76-83.
Ogg, G., 2009. International stratigraphic chart. International Commission on Stratigraphy.
Peters, K., Moldowan, J., 1991. Effects of source, thermal maturity, and biodegradation on the distribution and isomerization of homohopanes in petroleum. Organic geochemistry 17, 47-61.
Peters, K.E., Peters, K.E., Walters, C.C., Moldowan, J., 2005. The biomarker guide. Cambridge University Press.
Sepehr, M., Cosgrove, J., 2004. Structural framework of the Zagros fold–thrust belt, Iran. Marine and Petroleum Geology 21, 829-843.
Sherkati, S., Letouzey, J., 2004. Variation of structural style and basin evolution in the central Zagros (Izeh zone and Dezful Embayment), Iran. Marine and Petroleum Geology 21, 535-554.
van Buchem, F., Letouzey, J., Gaumet, F., Rudkiewicz, J., Mengus, J., Baghbani, D., Sherkati, S., Asillian, H., Keyvani, F., Ashrafzade, R., 2001. The petroleum systems of the Dezful Embayment and Northern Fars (south-west Iran). NIOC-IFP Joint Study Research Project.
Ziegler, M.A., 2001. Late Permian to Holocene paleofacies evolution of the Arabian Plate and its hydrocarbon occurrences. GeoArabia 6(3), 445-504.