The Nubia is the primary reservoir in the Gulf of Suez. However, the Nubia is not a single uniform sandstone unit; it ranges in age from the Palaeozoic (e.g. Nubia C) to the Cretaceous (e.g. Nubia A) and was deposited in alluvial/fluvial to paralic environments. This study investigates the influence of the reservoir architecture and changes in rock quality on reservoir performance.

A complete integration of available conventional core analyses, petrographic data, and openhole wireline logs through-out the Gulf of Suez was conducted. The specific aim was to understand the commonly observed deterioration in rock quality with depth. Although this reduction in rock quality may be only a couple of porosity units it has an order of magnitude effect on permeability. A more focus investigation of reservoir performance including production logs was then performed on the October (Nubia A) and Ramadan (Nubia C) fields. In the Ramadan area Nubia reservoir performance is primarily a function of grain size and clay content; however, in the October field it is more influenced by lithofacies changes.

The changes in rock quality have resulted in different reservoir management practices in these two mature oil fields. In October field, reserves have been maximised through a programme of successive water shut-offs isolating each reservoir layer as it waters-out. Whereas in Ramadan by-passed oil is in the deeper, lower permeability zone and was recently accessed by drilling a horizontal well.