The present work introduce a trial to delineate the reservoir rock types (RRTs) and also determining the effect of sedimentary microfacies in the Nubian reservoir quality of the Saqqara field, southern Gulf of Suez region, Egypt. Where it is considered a way to develop and enhance the oil potentiality of this field. Therefore, petrographical investigation and evaluating petrophysical core parameters of studied samples have been utilized. The petropgraphical core investigation reveals that illite, kaolinite, pyrite and patchy dolomite are the main authigenic constituents, while the components of relatively less common is the euhedral syntaxial quartz. Furthermore, analysis of the reservoir samples by using Scanning Electron Microscope (SEM) reflecting that the dominant framework grains are detrital clays, feldspars and quartz minerals. The studied Nubian reservoirr could be subdivided into two RRTs. The best reservoir quality is represented by the rock type RRT1, which has the following characteristics; flow zone indicator (FZI) varies from tight to very good (3.2 - 10.5 μm), reservoir quality index (RQI) ranges from tight to good (0.69–1.98 µm), poor to very good porosity (7.3 -19.0 %), and horizontal permeability detected from fair to excellent (2.0 md - 2719 md). Though it is made up of quartz wackes microfacies. The reservoir rock type 2 (RRT2) characterized by tight to good FZI (0.65 - 6.10 μm), tight to good RQI (0.02 -0.86 μm), the horizontal permeability ranged from 0.0 - 570.0 md and the porosity reach to 17 %. Petrophysical reservoir parameter results indicate relatively good reservoir parameters and good thickness of oil potentiality for RRT1rather than RRT2 types. The abundance of detrital clays like patchy siderite and kaolinite minerals, is a major factor in reducing point porosity.