Integrated evaluation of shale source rock potential in the Pabdeh Formation, Shadegan oil field, SW Iran

This study evaluates the hydrocarbon generation potential of the Pabdeh Formation's shales in the Shadegan oil field, southern Iran, a region recognized for its rich organic content. Samples from wells (SG 2, SG 4, and SG 20) were analyzed using advanced petrological, geochemical, and petrophysical techniques, specifically XRF, SEM-EDS, XRD, Rock-Eval, and GC-MS. Three facies groups were identified in the Pabdeh Formation: limestone facies (bioclastic wackestone microfacies and mudstone-wackestone microfacies) and calcareous shale facies, along with three distinct sedimentary sequences. Geochemical assessments revealed that shale samples from this formation, particularly from the middle section and within the calcareous shale facies, contain organic matter ranging from 1% to 5%. This organic matter, identified as Type II kerogen, exhibits early thermal maturity, indicating it has entered the early oil generation window. Mineralogical and elemental composition analyses further suggest that the Pabdeh shales originated from the erosion of acidic igneous rocks within a tectonically passive continental margin environment. This research significantly contributes to identifying the source rock and evaluating the hydrocarbon generation potential within the Shadegan oil field.