Nubian Sandstone reservoir characteristics: sedimentological and petrophysical evaluation in the Southern Gulf of Suez, Egypt

Abstract

The Nubian Sandstone is a thick sequence of clastic and thin carbonate sediments in the Jebel El Zeit section of eastern Egypt. The sequence is composed mainly of sandstone with shale and minor carbonate interbeds and was deposited in continental and fluviomarine to marine settings. Petrographically, quartz arenite and quartz wacke are the main facies of Nubian Sandstone. They have different secondary components, cement and matrix types, reflecting their different depositional environments and diagenetic histories. The Nubian Sandstone is one of the most prolific hydrocarbon reservoirs in the Gulf of Suez oil province.The Nubian Sandstone has good reservoir quality with porosity varying from 10% to 29%, and permeability of up to 5000 millidarcies. The quality of the reservoir depends on its proportions of shale, diagenetic history and the depth of burial (compaction). X-ray diffraction and scanning electron microscope analyses indicate that kaolinite is the main clay mineral and is derived from the alteration of potash feldspar. Enhancement of oil recovery from the reservoirs of the Nubian Sandstone can be achieved by alkaline injection to dissolve the kaolinite.