Publications

The presence of many near surface anomalies has caused strong seismic absorption on the 3D seismic covering the Sisi-Nubi area. On the vintage PSDM data processed in 2011, this geophysical artifact was not properly corrected especially at the shallow interval (500 - 1800 ms), resulting in a poor signal-to noise ratio within the affected zones. Consequently, this has limited the seismic ability to identify the shallow gas accumulations which are believed to be widely distributed vertically and laterally across the study area. A Q-PSDM reprocessing over an area of 420 km2 had been carried out with the aim to improve the seismic quality, focusing at the Sisi-Nubi’s shallow interval. In this paper, we demonstrate how Q tomography and Q migration could help recovering the seismic amplitudes and improving the structural images. A total of eight iterations of interleaved Q and velocity tomography updates were performed to optimize the Q and the velocity models. Detailed model building methodology and the achieved final Q migration result will be explained in this paper. The project has brought a better seismic imaging at the processing target window. The sand channels within the shallow interval are now better imaged as a result of Q model which successfully recovered the absorbed seismic amplitude. The Q-PSDM result will be used in further studies in order to evaluate the full potential of the shallow gas accumulations in Sisi-Nubi area.