The heterogeneous nature of carbonate reservoirs necessitates an integrated evaluation of depositional, diagenetic, and mechanical attributes to predict their reservoir potential. The Sarvak Formation, a key Cretaceous carbonate reservoir in the Zagros Basin, hosts major hydrocarbon reserves in Middle East. This study combines petrographic observations, routine petrophysical measurements, and wireline logs to describe depositional microfacies, diagenetic features, geomechanical units (GMUs), and reservoir rock types. Six microfacies were identified, ranging from distal mid-ramp to lagoonal settings. Various diagenetic processes influence reservoir quality and connectivity of the pores. Four third-order sedimentary sequences were identified from the vertical stacking patterns of the microfacies. According to Lucia's classification, six reservoir rock types were defined, with reservoir quality increasing progressively from RT0 to RT5. Comprehensive geomechanical analyses, including unconfined compressive strength, Young's modulus, shear modulus, and Poisson's ratio, were conducted. The results show that these mechanical properties strongly control reservoir stiffness, ductility, and fracture susceptibility, and consequently influence fluid flow and storage capacity. Based on K-means clustering, four GMUs were identified, exhibiting a progressive increase in reservoir quality. GMU1 is predominantly associated with rock types 0 and 1, whereas GMU4 corresponds mainly to rock type 4, highlighting the systematic relationship between geomechanical behavior and reservoir rock quality. The integrated analysis of microfacies, diagenetic alterations, and geomechanical units demonstrates that reservoir quality improves from GMU1 to GMU4. Early transgressive systems tracts are mechanically stiff and contain limited porosity. In contrast, the overlying regressive systems tracts particularly in sequences 3 and 4, exhibit highly connected pore networks and superior fluid-storage capacity. These findings highlight the critical role of facies–diagenesis interactions in controlling both petrophysical and mechanical properties, providing a robust framework for reservoir characterization.