Carbonate Depositional Environments and Reservoir Properties of the Miocene Rocks, East Gulf of Suez, Egypt: ABSTRACT

Abstract

Miocene carbonate rocks in six surface sections on the eastern side of the Gulf of Suez were carefully studied in the field, petrographically examined, and mineralogically analyzed using SEM and x-ray microanalysis for all elements. In general, reservoir quality of the Miocene carbonates was poor because of original composition and texture. Three different types of porosity were distinguished in the studied Miocene carbonates: primary (intergranular and moldic), secondary (leached), and fracture. Much of the porosity in the Miocene reservoirs is secondary; however, sometimes this secondary porosity may be reduced by compaction and/or precipitation of evaporites in fractures and pores. The authors conclude that the primary porosity of the carbonate rocks in the reef complex was eliminated by lithification and cementation; only secondary porosity remained. This secondary porosity developed in all environments (supratidal, intertidal, and subtidal), but the best porosity developed in the subtidal facies. This high porosity occurs because the dolomites in the subtidal facies are coarser and free from anhydrite cement, whereas in supratidal and intertidal facies the dolomites are finer and their porosity is plugged by secondary anhydrite cement.