The present work aims to flash up at the microfacies and integration of reservoir properties of 86 core limestone samples collected from Matulla Formation (Upper Cretaceous) at Gabal Libni were collected. The studied Matulla Formation is classified into five types of microfacies: Dolostone, Echinoidal foraminiferal grainstone, Echinoidal foraminiferal packstone, Echinoidal bioclastic packstone/grainstone, and Molluscan echinoidal packstone, the studied samples reveals most of the carbonate samples were tight, and various diagenetic processes including Dolomitization, Neomorphism, and Dissolution with iron oxides, carbonates, or clays. The porosity of rock samples directly affects the bulk density, as it increases if the porosity is filled by oxides (iron oxide) or cemented by clay content (cementation). The limestone reservoir reflects poor characteristics in most intervals as a result of low porosity and low permeability due to matrix and diagenesis. The reservoir quality index (RQI) is controlled mainly by permeability and the reservoir quality of carbonate rock samples are very low. The FZI for all carbonate microfacies ranged from 0.06 to 1.91 μm which infers impervious to poor reservoir quality. The pore throat radius R35 ranges from 0.01 to 2.66 µm, comprised of micro-mesoporosity 0.01 µm < R35 ≤ 2 µm, due to their tight nature, are generally impervious to poor flow potential and the studied carbonate microfacies are expressed by two hydraulic flow units.