Microfacies Analysis and Diagenesis Processes of Yamama Formation in Selected Wells of Fihaa Oilfield, Southern Iraq

This study focused on explained the carbonate microfacies of Yamama Formation and the impact of diagenesis processes in selected wells of Fiahaa oilfield in south of Iraq. The study showed distinctive microfacies that indicate different paleoenviroments. The inner ramp environment is subdivided into shoal, open marine and restricted environments. The shoal environment microfacies include peloid packstone, bioclastic peloidal packstone and benthic foraminiferal peloidal packstone. Restricted marine environment microfacies include grainstone, mudstone, peloidal wackestone -packstone, packstone and lithoclast packstone. Open marine environment microfacies include the foraminiferal packstone and wackestone, bioclastic packstone and coral boundstone. Lagoon marine environment microfacies include bioclastic packstone and algae wackestone. Mid-ramp environment microfacies include foraminiferal peloidal packstone, bioclast packstone, bioclastic foraminiferal wackestone. Outer ramp environment is distinguished by foraminiferal peloid packstone, bioclastic packstone, peloid bioclastic packstone and peloidal bioclastic wackestone. In the current study Yamama Formation affected by diagenetic processes which are classified into two major types: destructive diagenesis processes; such as compaction, chemical dissolution and Micrtization, and constructive diagenesis processes include cementation (Blocky, Drusy, Syntaxial rim), Dolomitization, Fractures.