Analysis of microfacies, sedimentation conditions and reservoir potential of Sarvak Formation (Cenomanian- Turonian) with emphasis on flow units in one of the oil fields in the Khuzestan Province, folded Zagros

Sarvak Formation is one of the important oil reservoirs in the Zagros Basin. In this study, 150 thin sections were evaluated to identify microfacies and sedimentation conditions and diagenetic processes. Porosity and permeability data were used to determine the flow units and to analyze the Reservoir quality by Lucia petrophysical method. Petrographic study led to the identification of 10 microfacies belonging to lagoon facies belts, Barier , middle ramps and outer ramps that were deposited in the environment of homoclinal carbonate ramps. The most important diagenetic processes identified in the Sarvak reservoir include cementation, dissolution, dolomitization, fracture and stylolitization. Analysis of porosity-permeability data using FZI index also led to the identification of 3 hydraulic units. The HFU1 unit with the weakest reservoir status is mainly characterized by lagoon microfacies and outer ramps, and the HFU2 and HFU3 reservoir units have a better reservoir status and mainly have lagoon facies belt, carbonate bar and middle ramps. Porosity, permeability, reservoir quality index, flow zone index and reservoir potential showed that the reservoir status of Sarvak Formation in the study area is in good to very good class. It can also be said that for each facies belt, lagoon facies and carbonate bar have better reservoir indices. The different reservoir status of the facies belts of Sarvak Formation shows the combined performance of sedimentary and diagenetic processes and has a complex effect on the reservoir sequence and its reservoir parameters in Southwest of Iran.