Microfacies and paleoenvironment of the Mishrif Formation (middle Cenomanian–early Turonian), in Nasiriyah oil field in Southern Iraq

Abstract

The Microfacies analysis of the Cretaceous Mishrif Formation was studied in Nasiriyah oil field in Nasiriyah Governorate, southern of Iraq using integrated borehole data set that included, core samples and well logs in newly drilled well to analyze the microfacies and the Diagenesis Process of the formation, 100 thin sections for selected well. The results show that the formation composed of: (top to base) a fine-grained, limonitic fresh water limestone containing Charophytae. Four facies’ associations were distinguished in the Mishrif Formation. These include: - These include: - Restricted shallow Open Marin environment is represented by Wackstone and Mudstone to Wackstone. The shallow open marine environment is represented by bioclastic wackestone and packestone, as well as rudistid floastone in rare situations. Shoal Environmentis represented by bioclastic packstone to grainstone, as well as rudstone. Deep Marine environment is represented by mudstone to packstone. six diagenetic processes affected on Mishrif Formation: Cementation, Micritization, Recrystallization, Dissolution, Compaction and Pressure Solution (Stylolization), and Dolomitization, found in thin sections.