This study aims to investigate the impact of clays on the quality of the Nubia reservoir in the
Saqqara field, Gulf of Suez, Egypt. The research will contribute to a broader knowledge of reservoir
characterization, offering valuable insights for similar geological settings in other regions, thereby
aiding in the optimization of resource management in global petroleum industries. The shale
evaluation procedure involves three primary steps: estimating shale volume, identifying clay
minerals, and assessing shale distribution. The neutron-density (N-D) method was employed to
estimate the shale volume in the Nubia reservoir, yielding an average of 0.6% across four wells, with
a maximum recorded value of 2.2% in well GS323-3. These values represent that the Nubia reservoir
contains a negligible amount of shale, indicating that the porosity and permeability are high. Clay
mineral analysis, based on a Potassium-Thorium (K-Th) and Potassium-PEF cross-plots, identified
the presence of chlorite, illite, montmorillonite, and heavy thorium-bearing minerals, where chlorite
and illite enhance the mechanical stability of the reservoir, while montmorillonite may cause issues
with swelling and pressure. Thorium-bearing heavy minerals are typically associated with reduced
permeability due to their influence on chemical interactions. The shale distribution analysis, conducted
using the Thomas and Stieber model, confirms the overall cleanliness of the Nubia reservoir. Most
formation data points align with the 0% shale line, indicating high total porosity, while only a
few points fall along the dispersed shale line. In conclusion, the findings indicate that the Nubia
reservoir exhibits minimal shale content, predominantly clean lithology, and favorable porosity and
permeability characteristics. Consequently, the reservoir is classified as high-quality, making it suitable
for efficient hydrocarbon production.