Source rock and shale oil potential of the Pabdeh Formation (Middle–Late Eocene) in the Dezful Embayment, southwest Iran


  • B. Alizadeh Department of Petroleum Geology and Sedimentary Basins, Faculty of Earth Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Golestan Boulevard, Pin: 613578-3151 Iran. Petroleum Geology and Geochemistry Research Center (PGGRC), Shahid Chamran University of Ahvaz, Ahvaz, Golestan Boulevard, Pin: 613578-3151, Iran
  • A. Opera Department of Petroleum Geology and Sedimentary Basins, Faculty of Earth Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Golestan Boulevard, Pin: 613578-3151 Iran.
  • M. Kalani Department of Geology, National Iranian South Oil Company (NISOC)Ahvaz, Pasdaran Highway, Pin: 61735-1333, Iran
  • M. Alipour Department of Petroleum Geology and Sedimentary Basins, Faculty of Earth Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Golestan Boulevard, Pin: 613578-3151 Iran.



Pabdeh BSU, Organic matter, Biomarkers, Mineral composition, Oil potential.


The Pabdeh Brown Shale Unit (BSU) is an organic-rich calcareous mudstone within the Paleogene Pabdeh Formation, which has not yet been investigated in detail. A total of 166 core and cutting samples were selected from four wells in the Dezful Embayment to investigate the organic geochemical and the mineralogical compositions, as well as the shale oil potential of the BSU. XRD results show that it is mainly comprised of calcite (53wt.%), clay minerals (25wt.%), and quartz (14wt.%). TOC contents generally range from 1 to 9wt.% (avg. 4.2, 2.9, 5.2 and 3.3wt.%, for GS, KR, RR and RS wells, respectively) with HI values ranging between 400 and 650 mg HC/g TOC. Based on average values of Tmax and vitrinite reflectance, as well as saturate biomarker ratios, the BSU is immature at wells RR and RS (ranging from 0.3 to 0.53%) and its maturity increases northward at wells KR and GS (ranging from 0.5% to 0.67%). The organic matter is dominated by Type ΙΙ kerogen and is generally composed of liptinite and amorphous material with minor terrestrial input. Based on various biomarker parameters, the organic matter was most likely deposited under anoxic marine conditions. The mineralogical characteristics (i.e. presence of brittle minerals) and organic geochemical properties (i.e. TOC >2wt% and Type II kerogen) support the conclusion that the Pabdeh BSU displays a considerable shale oil potential where it attains appropriate thermal maturity.



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