Bioerosion, Secondary Porosity and Reservoir Heterogeneity in Middle Miocene Reefal Carbonates: An Outcrop Analogue From the Gulf of Suez, Egypt

The well‐exposed Middle Miocene reefal carbonates of Wadi Kharaza (Gebel Abu Shaar), along the southwestern coast of the Gulf of Suez, Egypt, provide an excellent outcrop analogue for investigating the development and distribution of porosity in the subsurface Nullipore reservoir. Field observations and petrographic analyses reveal that secondary porosity varies considerably within the reef framework and represents an important contributor to reservoir heterogeneity. Among the recognized biogenic features, bioerosion—predominantly represented by the Trypanites Ichnofacies—appears to have played a significant role in porosity development through the generation of secondary voids and the modification of the primary skeletal framework. In addition, dissolution of coral colonies and molluscan shells contributed to secondary porosity, although some dissolution cavities were subsequently partially or completely occluded by calcite cement, locally reducing reservoir quality and pore connectivity. These findings highlight the interplay between reservoir‐enhancing processes, particularly bioerosion and dissolution and reservoir‐deteriorating processes such as calcite cementation, which together control porosity development and reservoir heterogeneity. The correlation between the Middle Miocene reefal carbonates of the surface outcrops and the Nullipore reservoir of the Gulf of Suez may act as a framework for evaluating how the observed surface facies and pore‐system characteristics may help constrain the subsurface reservoir architecture and heterogeneity.