Adel Khalil

RTM Noise Attenuation and Image Enhancement Using Time-shift Gathers

Reverse time migration (RTM) has become a central tool in seismic imaging, especially in complex geologies where other migration methods fail. However, the way RTM is generally formulated introduces various types of artifacts, these include low-frequency noise in high velocity-contrast areas and shear-wave-like noise when anisotropy is included in the formulation. Using time-shift gathers from the extended imaging condition, we develop a method to effectively attenuate these artifacts and further enhance the final image by refocusing the migrated energy. We demonstrate the results of our method on both real and synthetic data sets.

Deblending of simulated simultaneous sources using an iterative approach: an experiment with variable-depth streamer data

We have simulated a simultaneous source experiment with a real variable-depth streamer NAZ survey acquired in Brazil and applied an iterative separation flow using a hybrid of median and f-x projection filters for deblending. The results show little leakage after deblending in both near and far offsets while preserving the AVO characteristics. We have also performed Kirchhoff migration in order to examine the residual cross-talk in common image gathers after deblending. The results reveal little leakage, and the quality of the common image gathers is adequate for velocity model building. We also study how the existence of spatial aliasing when shots are coarsely sampled degrades the deblending quality. Lastly, the impact of firing multiple sources simultaneously to improve shot sampling is investigated.

An optimized workflow for coherent noise attenuation in time-lapse processing

In the time-lapse processing paradigm, a method has recently been proposed to simultaneously adapt multiple models in such a way that 4D differences are optimized (Zabihi et al., 2012). We build on this idea in developing a seismic processing workflow which is optimized for 4D signal enhancement in a more generalized manner, at a lower cost and with minimal impact on turnaround. The workflow is tested on real data with significant improvements in the final 4D product.