Hydrocarbon Potential of the Pabdeh Formation: Geochemical Insights Into Immature Source Rock Capabilities

The Pabdeh Formation (Paleocene-Oligocene) is one of the hydrocarbon-generating formations in the Zagros sedimentary basin. In this study, to evaluate its hydrocarbon potential and the distribution of organic matter maturity, samples were collected from oil fields in southwestern Iran and the Dezful embayment and analyzed geochemically. For a more detailed assessment, the study area was divided into northern and southern sections. The results of Rock-Eval pyrolysis, based on variations in PI, HI, and T_max indices, indicate that the Pabdeh Formation is predominantly immature, with only about 15% of the analyzed samples falling within the early oil window. The formation contains Type II and Type III kerogen, as well as a mixture of both. In terms of hydrocarbon potential, the results reveal a range from poor to very good oil-generating capacity. However, the organic matter maturity remains within the immature to early oil window stage. From a depositional environment perspective, the Pabdeh Formation was mainly deposited in relatively anoxic conditions, with some samples found in the continental slope setting. If these samples reach sufficient thermal maturity, they could exhibit favorable hydrocarbon generation potential. These findings provide valuable insights into the thermal maturity distribution and hydrocarbon potential of the Pabdeh Formation within the Dezful embayment, which could be beneficial for hydrocarbon reservoir assessments in this region.