Investigating Hydrocarbon Generation Potential of Pabdeh (Tertiary) and Kazhdumi (Early Cretaceous) Source Rocks in Abadan Plain, Southwest Iran

The most important source intervals through Cretaceous to Tertiary succession in the Zagros basin which generated most of the oil and gas in the Cretaceous reservoirs include Garau, Gadvan, Kazhdumi and Pabdeh formations. In this study, the Tertiary Pabdeh and Early Cretaceous Kazhdumi formations were geochemically investigated. More than 87 core and cutting samples were collected from 22 exploration wells of 13 oil fields in the Abadan Plain, south-west of Iran. After required preparations, samples were subjected to Rock-Eval pyrolysis and organic petrography in order to measure their generation potential and thermal maturity levels. The results showed that Pabdeh Formation with an average TOC of %1.25 and average HI of 145 mg HC/g TOC can be regarded as fair to good source rock, whereas Kazhdumi Formation with average TOC and HI values of %1.8 and 278 mg HC/g TOC, respectively, is found to be a good to very good source rock. Maturity indicator parameters; such as, Tmax and vitrinite reflectance indicated an immature stage for the Pabdeh Formation in the Abadan Plain. However, the maturity levels for the Kazhdumi Formation range from immature level in the western part of the study area to the beginning of the oil window in the eastern part and in the vicinity of the Dezful Embayment. The iso TOC map and the Tmax maps of Pabdeh and Kazhdumi formations in the studied area revealed an eastward increasing trend for the production potential and organic matter maturity toward the Dezful Embayment.