Microfacies, Sedimentary Environment, Diagenesis and Petrophysical Evaluation of the Sarvak Formation in the framework of Sequence Stratigraphy in North-Dezful Embayment, southwestern Iran

The subsurface section of the Sarvak Formation with a thickness of 455 m is located in the North-Dezful Embayment. The Sarvak Formation is underlain by the Ilam Formation with erosional discontinuity and is overlain probably by the Shale of the Kazhdumi Formation (due to the lack of drilling to the underlying boundary). The probable age of this formation is Albian–Turonian. Based on petrographic studies of 2111 thin sections from cutting, the dominant lithologies are limestones and dolomitic limestones. Facies analysis has led to the identification of nine microfacies in three facies belts of the lagoon, bioclastic shoal and shallow open marine. The gradual changes in microfacies, lack of calciturbidite, slump structure and absence of large reefs structure, confirm the ramp type-carbonate platform. Diagenetic processes consist of micritization, neomorphism, physical and chemical compactions and dissolution. These processes have changed the reservoir quality of the Sarvak Formation. The quality of the reservoir is carried out in the framework of sequence stratigraphy and the Sarvak Formation is divided into third depositional sequences and six system tracts, and the reservoir potential of each system tracts was calculated and the result have shown 6 reservoir zones, which transgressive systems tract (TST)from the second depositional sequence has the highest reservoir potential in this well.