<p>The Tuscaloosa Group of the southern Mississippi Embayment (MSE) comprises shale, claystone, and sandstone units. The Upper and Lower Tuscaloosa formations are recognized as essential hydrocarbon reservoirs in the southeastern United States, as well as significant aquifers located near the surface; however, their reservoir potential within the confines of our specific study area has yet to be thoroughly assessed. Given the economic importance of these formations and the wealth of old well log data available, there is a compelling need to develop improved methods for predicting potential reservoir quality in underexplored areas of the MSE. This investigation is driven by the imperative to maximize the utility of legacy subsurface datasets through their integration with contemporary petrographic methodologies, thereby enhancing our comprehension of diagenetic influences on porosity evolution and permeability heterogeneity. The primary goal of this study is to conduct comprehensive petrographic analyses of sand and sandstone samples from the Tuscaloosa Group to examine diagenetic properties controlling porosity and permeability variations and to determine how these properties correlate with available wireline log data. The results reveal that grain size distribution ranges from very fine to coarse sand, averaging fine sand, with moderate to moderately well sorting. Compositionally, the sands and sandstones are predominantly quartz arenite, with subordinate subarkose, sublitharenite, quartz wacke, and lithic wacke. The framework grains include abundant monocrystalline quartz, with lesser amounts of glauconite and polycrystalline quartz, plus trace feldspars and accessory minerals. Post-depositional modifications include clay, carbonate, and hematite cementation, grain dissolution, and mechanical compaction features. Quantitative analysis demonstrates that mechanical compaction reduced porosity more substantially than cementation, with compactional porosity loss (COPL) reaching ~ 23.0% compared to cementational porosity loss (CEPL) of 7.7%. Integration of petrographic observations and statistical analysis yielded nine diagenetic facies with distinct potential reservoir quality characteristics. The correlations between spontaneous potential (SP) values and diagenetic facies find that SP logs alone identified only three of the nine diagenetic facies, highlighting limitations in single-log characterization approaches. This study demonstrates that accurately predicting the distribution of diagenetic facies and associated potential reservoir quality necessitates a multi-parameter approach rather than relying solely on conventional SP log interpretation. Integration of wireline log data with detailed petrographic analysis can create a strong foundation for predicting variations in reservoir quality within the economically important strata of the Tuscaloosa Group. These insights enhance reservoir characterization techniques in mature basins, allowing for better utilization of existing subsurface data.</p>