In this work, we evaluate an underexplored secondary target investigated in oil wells targeting Ghadames basin reservoirs in several oilfields, namely the TAGI clastic reservoir in Tunisia’s Ghadames Basin. Hence, we used sequential stratigraphy and petrophysical analysis results to evaluate reservoir quality and fluid saturation. It should be noted that the processed data are of a geological nature, primarily well logging. Two methods are employed to solve this issue: The Wylie equation and Archie’s low. The software used is the Interactive Petrophysics. The sequential stratigraphy, using GR data, showed that the TAGI reservoir is composed of nine sequences containing five reservoir zones (A, B, C, D, and E). The dominant sequences are bell, cylinder, and symmetric-shaped types, respectively. We distinguish substantial shale fractions between main sand bodies that form the seal layers between productive zones. The thickness and configuration of these depositional units exhibit variability. Some genetic units display symmetry, while others demonstrate asymmetry. In addition, there is a general tendency toward slight progradation in the TAGI reservoir, primarily due to the prevalence of cumulative progradational facies that contribute more significantly to the total thickness than retrogradational facies.