Potwar Basin is proven to be the most significant hydrocarbon potential resource area of the Indus Basin Pakistan, comprising of various carbonate oil and gas producing reservoirs of Eocene age. However, these reservoirs are depleting with unsustainable production rates, and low recovery factors, attributed to complex reservoir heterogeneity resulting from diagenesis. This study provides an integrated reservoir characterization of the Chorgali-Sakesar carbonate formation to analyze its diagenetic and mineralogical impact on reservoir quality. The comprehensive analysis includes petrography of thin sections, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), Fourier Transformed Infrared Spectroscopy (FTIR), Gas permeability and Helium porosity measurements. Outcomes indicating an average porosity and permeability values of 5.31%, and 0.89mD respectively; revealing poor to moderate reservoir quality primarily influenced by secondary origin due to diagenetic alterations. Petrographic analysis classified the three discrete microfacies of dolo-mudstone to bioclastic pack-grainstone with distinct diagenetic features and micro-nano fossil assemblages, including bioclast, intraclasts, nummulites, Assilina, and LBFs. Diagenesis significantly impacts petrophysical properties, increasing reservoir heterogeneity through processes like micritization, cementation, and compaction. The specified depositional environment of the formation exposed the alteration during distinct diagenetic phases in marine, meteoric, and burial diagenetic settings. Pore morphology and mineralogy reveals the complex micro-pore structure with various carbonate mineral phases and cement types, further influencing reservoir heterogeneity and fluid flow potential. In conclusion, the CHG-SKR formation exhibits intricate reservoir heterogeneity and varied micro-pore structure due to diagenesis and depositional settings. Its non-uniform pore geometry, and low petrophysical properties resulting from rock compaction classified it as low-quality reservoir. The findings provide a solid foundation for addressing the key challenges in reservoir characterization, and accurately assessing reservoir quality, with implications to mitigate reservoir management risks, and improving productivity of indigenous resources. It offers valuable insights for optimizing resource extraction strategies in the exploration and exploitation of indigenous resources worldwide.