Facies Analysis, Depositional Environment and Reservoir Zonation of the Upper Part of Surmeh Formation (Arab Formation) in one of the Persian Gulf Fields

Surmeh Formation is one of the major reservoir formations in the Persian Gulf. In this research, facies, depositional environments, diagenetic processes and reservoir zonation are investigated in one of the fields in the Persian Gulf. Sedimentological study of the cores and thin sections of 3 wells from this field has led to the identification of 8 facies. These facies were deposited in four facies belts including supratidal, intertidal, lagoon and shoal. The sediments of this formation were deposited in a homoclinal ramp carbonate platform in arid condition. Diagenetic processes affecting these sediments include micritization, dolomitization, neomorphism, compaction, cementation, and dissolution. Among these processes, dolomitization and dissolution have a positive effect, and cementation (esp. anhydrite cement) and compaction have a negative effect on reservoir quality. Based on lithology, microfacies and poroperm data, 6 rock types have been identified. Integration of these date, caused to identity 7 reservoir zones which indicating a shallowing upward cycles. Each zone consists of one dolomite layer with fair to excellent reservoir quality witch capped by the anhydrite layer as a barrier. According to this, lithology, microfacies and diagenesis are the controlling factors of the studied interval, respectively.