3D Seismic Depth Imaging As An Approach To Improve Pre-Salt Structures, Ras Garra Area , Gulf Of Suez , Egypt

By

 R. Awad¹, I. Desoky¹

(1) Petrobel oil Company, Cairo, Egypt

 The Ras Garra Development lease is located on the southern part of the Gulf of Suez, The exploration activity started in this area by acquiring the first 2D Marine seismic survey in the Gulf of Suez in 1955. In 1995 , the area of interest was covered by 3D seismic survey (220 sqkm) to optimize field development and exploitation.

The primary target is represented by pre-evaporitic sedimentary Miocene sequence . The impact of the presence of salt bodies on the seismic image in Time domain is relevant, it affects the ray path, producing a deviation of the ray, reduces the penetration of the energy under the salt layer and produces a pull-up effect under the salt. This makes difficult the correct definition of the fault heaves, his position and the dip of the reflectors, increasing the uncertainty about the size and the spatial position of the prospects.

Owing to the structural complexity, due to the presence of an irregular salt body above the target, we followed an approach based on depth imaging: the construction of a Velocity Volume and a full 3D Pre Stack Depth Migration (3D Pre SDM).

The final depth migrated 3D seismic volume showed a general improvement of the image of the subsurface:

- New structural features were indeed highlighted in the Pre-Evaporitic sequence.

- A better definition of the normal faults pattern that created the trap system in the area.