Geochemical Evaluation of Source Rocks and Reservoir Oils of One of the Oil Fields in Abadan Plain

In this research, the hydrocarbon generation potential of probable source rocks was evaluated. Results of the Rock-Eval pyrolysis showed that, among the studied samples, the Pabdeh and Kazhdumi formations contained marine type-II/III kerogen and showed good to very good oil generation potential, making their organic matter (OM) immature and immature-in early oil production window, respectively. Containing mixed type-II/III kerogen, the Gadvan Formation was found to be within the oil production window, in terms of maturity, showing good hydrocarbon generation potential. The Sargelu and Garau formations were found to be dominated by type-II kerogen, exhibiting very good hydrocarbon generation potential. It was further figured out that the Garau and Sargelu formations were in the middle and late oil production window to early wet gas window, respectively. Outcomes of geochemical analyses on the studied crude samples showed that all of them were originated from the same source, with the potential source rock exhibiting a marl-carbonate lithology deposited in a reducing environment. The OM content of the probable source rock was primarily made from type-II kerogen formed in a marine environment, with evidence of intrusions by OMs dominated by terrestrial kerogen has been further observed. The studied crude samples were found to be sourced from Lower Cretaceous to Middle Jurassic source rocks with maturity levels corresponding to middle to late oil production window so that the crude samples from the Fahliyan Formation exhibited the highest levels of maturity. Sargelu and Garau formations were proposed as potential source rocks for the crudes accumulated in the Abadan Plain.