Sequence Stratigraphy and Sedimentary History of the Neogene Nile Delta

By

Ahmed N. El-Barkooky¹, Mohamed A. Helal²

(1) Cairo University, Cairo, Egypt (2) Shell Egypt, Cairo, Egypt

 The Neogene System is increasingly considered as the primary target for hydrocarbon exploration in the Nile Delta. The present work aims at constructing a regional stratigraphic framework to help understand the reservoir distribution. Proximal-to-distal variation of depositional sequences are inferred from regional, geoseismic transects calibrated by well data. Thirteen third order sequence boundaries and 6 maximum flooding surfaces were identified.

The development of the Nile Delta/River system was controlled by both the East Mediterranean basin evolution and the African Hinterland. The Nile system started during the Late Miocene with deep canyon incision into pre-existing Cenozoic/Mesozoic sequences leading to transportation of huge amounts of sediments to the Mediterranean. At least three incisions are seismically recognized with type-I sequence boundaries: the oldest is Tortonian and the youngest is Messinian. The proximal in-fill of these canyons is thick, coarse alluvium getting sandier with more marine influence northwards. The far reaches of these canyon systems bear a great potential of excellent low-stand reservoir.

More than 2km thick salt is seismically defined in the far-offshore and assigned to the Late Messinian salinity crisis. In the near-offshore only few tens to hundreds of meters of evaporites exist, while almost absent from the onshore area.

Excellent Plio-Pleistocene reservoir is mainly linked to the lowstands, where sands were conveyed to the outer belts through incised canyons in the upper slopes tracking to submarine fans farther northwards. Mega-slumps were particularly active during Late Pliocene to Recent. They form significant stratigraphic packages in the lower-slopes and basin plain areas.