This study investigates the combined impact of sedimentary textures and diagenetic processes on reservoir quality within the Asmari Formation in the Parsi oil field, SW Iran. The objective is to evaluate how depositional microfacies and postdepositional alterations interact to influence porosity and permeability variations. A total of 1,412 thin sections from three wells were petrographically analyzed to identify sedimentary textures, microfacies types, and diagenetic overprints. Nine distinct microfacies and six primary sedimentary textures (mudstone to boundstone) were identified, spanning inner, middle, and outer ramp settings. Key diagenetic processes, including dolomitization, cementation, dissolution, and fracturing, significantly modified the original petrophysical properties. The eastern part of the field (well 69) shows enhanced reservoir quality due to pervasive dolomitization and open fractures, while the western region (well 19) exhibits reduced quality due to evaporite precipitation and limited dolomitization. This integrated analysis highlights that both primary depositional conditions and diagenetic evolution must be considered to accurately predict reservoir heterogeneity. The findings offer a predictive framework applicable to other carbonate reservoirs in similar tectono-sedimentary settings.

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