Depositional Environment Study of the Pabdeh Formation in Zeloi Oilfield using data obtained by Rock Eval 6 pyrolysis

Document Type : Original Research


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

2 Fundamental Geology, National Iranian Oil Company, Tehran, Iran


The purpose of this paper is to study the depositional environment of the Pabdeh Formation in Zeloi Oilfield, northern Dezful Embayment using data obtained by Rock Eval 6 pyrolysis. For that, 36 samples were selected from well number ZE5, which is located in the central part of the field, and analyzed by Rock-Eval 6. For the first time by geochemical methods and on the basis of Tmax and S2 values, this formation has been divided into three zones A, B and C. Zone B with higher TOC and S2 values has more hydrocarbon potential which is related to sea progressive time. The parameter S1+S2 versus TOC shows that production potential of this formation has wide variation and is within the ranges of poor to very good and in general has high potential. The diagram of HI to Tmax demonstrates that the kerogen content of this Formation has extensive dispersity and mostly includes Type II/III. It can therefore be concluded that, the depositional condition was uneven for the Pabdeh Formation. HI/OI diagram shows extensive variation on the Pabdeh Formation facies, which could be seen in the HI/TOC ratio, too. Also, HI/depth ratio demonstrates several sea regressive and progressive periods during the Pabdeh deposition. According to HI/TOC and sedimentary conditions Pabdeh Formation could positively act for hydrocarbon production.