oa Cost-effective Seismic Data Reprocessing for Subsalt Imaging Enhancement

The deep offshore is a challenge to seismic processing and imaging techniques, due to the complexity of the salt body structures and the omnipresence of mode conversions that mask the primary signal. Cost efficiency in the global recession because of the low oil price long standing issue could be motivated to look for another simple usable alternatives to the highly sophisticated techniques have been widely utilized in subsalt deep water imaging. Indeed Wide azimuth towed streamer WATS and even full azimuth single vessel coil shooting with high offset coverage and broad band seismic with extremely very low frequency less reaches 2.5 Hz was enables seismic energy penetrating the ultra-deep subsalt and brought a significant change in subsalt deep offshore imaging accordingly. The conventional offshore seismic data acquisition method known as Narrow-Azimuth Towed Streamer (NATS) and data collected this way, from just one direction (or azimuth), do not yield reliable images of the subsurface is not suited any longer for such a complex geology. Broadband seismic data has brought a new level of understanding to the mapping of these facies. Using the full spectrum of frequencies (from 2.5 Hz to 125 Hz). Pre stack depth imaging with advanced techniques such as the expensive and intensive computer CPU time such as RTM and FWI are proven technologies for high resolution velocity model with proper depth imaging techniques. They are the commonplace depth imaging techniques nowadays for complex subsalt geology seismic data type. However in this case studies to complying with cost optimization trend, another revisit of the subsalt legacy seismic survey deep offshore Angola was made to revoke if the seismic data quality could be improved and the residual seismic data concerns of those legacy seismic data sets could be overcommit.