Essential Link between Ancient Exploration Tools and the Latest 3D Reprocessing Techniques: A Rule for the Recent Geological Modeling in Very Complex Area (Ashrafi Field -- Gulf of Suez, Egypt)

By

A. Abd El Fattah¹, H. Aly¹, M. El Sheikh¹, M. Khalil²

(1) AGIBA, Cairo, Egypt (2) IEOC, Cairo, Egypt

 The sub-salt image in Ashrafi Field, southern Gulf of Suez, Egypt was re-mapped by using seismic reprocessed data applying the 3D Pre-Stack Depth Migration and a new methodology recently implemented by ENI-Agip Div.: the Phase Shift Plus Interpolation (PSPI) migration. I n the past poor seismic image related to seismic energy attenuation within the thick salt section, complex sub-salt structural pattern, steep dip in the pre-Miocene, high Basement relief, fast and drastic changes in the water depth hindered previous imaging and mapping projects in the area.

Analog surface models from the nearby Gebel El Zeit outcrops (Western Gulf of Suez Rift shoulder) indicated highly tilted pre-rift normal fault blocks (55 degrees dip) onlapped by different syn-rift facies with numerous unconformities.

Structural modeling of the recent improved seismic image in the Ashrafi field area supported by subsurface facies maps, formation tops and dipmeter data analysis from the drilled wells accompanied by a diligent study of the nearby outcrops models led to re-shaping the pre-Miocene block geometry and to identify new areas with remaining hydrocarbon potential.

The study reveals also the locations of the major accumulation of the Miocene syn-rift clastics reservoir by predicting their paleo-drainage and sediments entry points. As Ashrafi area remained significantly high during early and mid rifting time, erosion at the crests of the pre-Miocene blocks and deposition at their flanks controlled the syn-rift clastics rich areas.