Paleogeographic Controls on Porosity Evolution in Dolomitized vs. Karstified Reservoirs: Insights from the Zagros and Persian Gulf Carbonate Reservoirs

This study investigates porosity-depth trends in carbonate reservoirs of the Zagros and Persian Gulf regions, comparing regional data with global benchmarks to identify key controlling factors. An integrated dataset of Permian to Miocene carbonate reservoirs—including porosity, depth, and temperature—was analyzed using statistical and comparative methods to reveal systematic trends across lithological and stratigraphic groups. Results demonstrate that average porosity decreases systematically with burial depth, consistent with global patterns, but notable regional deviations exist. Cretaceous karstified reservoirs and non-Cretaceous dolomitized reservoirs follow distinct porosity-depth trajectories. Dolomitized reservoirs exhibit tighter data scatter, particularly below 2 km, while Cretaceous reservoirs show higher variability due to uplift, subaerial exposure, and meteoric diagenesis. Lithology and pore-system characteristics exert the strongest influence on porosity evolution, whereas geological age and geothermal gradient play secondary roles. Paleogeography acts as a higher-order control, governing depositional systems and diagenetic pathways that ultimately dictate porosity preservation or loss during burial. By integrating paleogeographic context with diagenetic history, this study provides a predictive framework for reservoir-quality trends, reducing exploration uncertainty in Zagros and Persian Gulf carbonate systems. Key findings reveal that Cretaceous karstified reservoirs retain higher porosity due to dissolution-dominated pore networks and humid paleoclimates, while dolomitized reservoirs experience greater compaction and porosity reduction under arid conditions. These differences are linked to the Arabian Plate's latitudinal migration and tectonic evolution over time.