The Gharif Formation is a crucial hydrocarbon reservoir in Oman, characterized by its complex lithology and clay mineral compositions due to its location at the interface of continental and marine settings. This study employs spectral gamma-ray (SGR) logs to identify clay minerals and assess the depositional environment within this formation, contributing to understanding hydrocarbon exploration and reservoir quality in West Central Oman. The identification of clay minerals and the assessment of the depositional environment were conducted through the utilization of a spectral gamma-ray (SGR) log. The SGR log indicated that the Middle Gharif Formation and Lower Gharif Formation are predominantly characterized by illite and mica, particularly noticeable in the eastern part of the study area. Clay mineralogy has significant implications for reservoir quality and permeability, particularly in the Middle Gharif Formation, where the presence of illite has been associated with reduced permeability. It's important to highlight that glauconite is noticeably lacking in the western section of the study area. The presence of glauconite in formation can indeed reduce permeability in formations with similar porosity. This reduction in permeability can lead to a deterioration in reservoir quality. However, the effect of the glauconite is greater than that of the illite. The interpretation of the depositional environment based on the thorium (Th)/uranium (U) connection indicates that a high Th/U ratio is characteristic of a continental environment, while a low Th/U ratio is typical of a marine environment. The Middle Gharif Formation shows high and intermediate Th/U ratios, suggesting a fluvial environment for sediment deposition. On the other hand, the Lower Gharif Formation exhibits low Th/U ratios, indicating a marine environment. The results follow the depositional environment trend of the field, where fluvial sediments are deposited in the proximal part (east), and marine sediments are found in the distal part (west).