Timing of Structural Development of Oil Traps in Gulf of Suez, Egypt

L. R. Chowdhary, S. Shaheen

To date, more than 40 oil fields with an estimated 25 billion bbl of oil in place have been discovered in the Gulf of Suez, Egypt. These oil accumulations are present both in the pre-graben and graben-fill cycles which are separated by Oligocene tectonic phase, hitherto considered to be responsible for differentiation and formation of oil traps. In the present study, the structural development of many oil traps is related to intra-Rudeis tectonic phase of late early Miocene age.

Presence of an angular unconformity within Rudeis Formation (early to middle Miocene) and nonangular unconformity between pre-Miocene and early Miocene Nukhul-lower Rudeis strata in Ras Budran, N. July, and Ramadan clearly suggest intra-Rudeis development of these structures. In other structures (Ras Bakr, Ras Gharib, Ras Fanar, Belayim Marine, S. July, Hurgada, Zeit Bay, etc), the exhumed pre-Miocene strata ranging in age from Paleozoic to Eocene (or even Precambrian basement as in Zeit Bay) are in uncorformable contact with graben-fill deposits of middle Miocene age. Structural development of these structural-unconformity traps can be related to either Oligocene or intra-Rudeis tectonic phase. However, a study of the development of erosional profiles would favor an intra-Rudeis orig n of these structures. A few structures with oil accumulations in graben-fill sandstone reservoirs, such as Morgan, W. Bakr, etc, were primarily formed following intra-Rudeis tectonic phase as a sedimentary drape and compaction structures over preexisting relief features.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.