No abstract

The explorative targets of the proposed case history are the Cretaceous sequences in a ENE-WSW fold related to the "Syrian Arc" event, and the overlying Oligocene to Miocene sequences that pertain to the Nile Delta System. The structural pattern is sealed by the evaporites associated with the Messinian Salinity Crisis. When facing such complexity the integration between interpreters and geophysicists is the key point in order to obtain a reliable imaging and hence a reliable geological model. Moreover, an integrated working platform is required to speedup the process that requires strong team interaction and a certain number of iterations to achieve the desired degree of confidence. The workflow started from the estimation of the velocity in the post-Rosetta where a global grid tomographic approach was used. Then for the Rosetta we initially assumed a tentative uniform velocity that resulted in some push-down and pull-up effects. Such effects were removed after geophysical and geological evidences provided information about the real geometries of Rosetta, allowing to tune velocity variations within salt. In the deepest part, the velocity analysis was even more complex because of the limited offset/depth (6000m/8000m) ratio. A modeling exercise gave confidence on the effective illumination of the deeper reflectors and a large scale grid tomography was performed. The final velocities in the pre-Rosetta showed two significant velocity inversions validated by geological models and analogues. The proposed workflow led to significant improvements of the imaging of pre Rosetta sequences, both in terms of SNR and geological reliability of the prospect structure with a consequent de-risking of the prospects. R. Marten, M. Shann, J. Mika, S. Rothe, and Y. Quist, [2004] Seismic challenges of developing the pre-Pliocene Akhen Field offshore Nile Delta, The Leading Edge a c b