Effect of petrography and diagenesis on the sandstone reservoir quality: a case study of the Middle Miocene Kareem Formation in the North Geisum oil field, Gulf of Suez, Egypt

Abstract Kareem Formation is one of the most important hydrocarbon reservoirs in Gulf Suez. It contributes significantly to total Egyptian oil production; therefore, current work emphasise influence siliclastic facies types and their diagenetic processes on reservoir quality Formation. A comprehensive log core analyses were used determine both petrophysical petrographical characteristics. Three classic have been identified: two sandstone with potential shale facies. Facies I coarse-grained high-angle cross-bedding, distributary/braided channel deposits active part a mid-submarine fan lobe represented by beds (Shagar Member). II fine-grained sandy low-angle crudely, cross-bedded encountered Rahmi Member. III mainly recorded clastic zone. Petrographically, quartz arenite microfacies are dominant Shagar sand zone show highest zones On other hand, lithic calcareous constitute major lowest quality. The main that enhance intervals microfracturing mineral grains dissolution feldspar carbonate cement. In contrast, amount cementing materials, particularly authigenic clay cements, led diminishing studied