Historically complex salt bodies (e.g. Canopy, Salt Weld…) can introduced serious imaging issues for geophysicists with distorted seismic images both beneath salt body and in the vicinity of the salt flanks or welds (Ian F. Jones, et al., 2014). This is mainly related to absorption and scattering of the seismic ray path. The challenge is to produce a velocity model that is consistent with a geological concept, enabling the delineation of the salt bodies geometry and imaging beneath the salt bodies. In order to tackle this problem, a robust velocity model building strategy using four focus points was implemented: input dataset, velocity model building (VMB) workflow, imaging algorithm and intelligent stacking described in this case study. First, using re-processed and de-ghosted dataset to bring out the low frequency content in the data. Second, a robust velocity model building workflow which comprises of tomography update, Full Waveform Inversion (FWI), salt body interpretation and manual Vp update. Third, imaging using Reverse Time Migration (RTM) algorithm in order to handle the complex ray path and sharp velocity contrast between salt bodies and sediment layers. Finally, post-imaging processing using intelligent stacking in order to benefit from the multi-azimuth illumination coming from the wide-azimuth seismic acquisition (post-migration processing on full azimuth data was performed as well). This workflow has proven to be successful in producing a better focused high-resolution final image in areas affected by the salts which can be integrated into any other future salt-based imaging project.
Note: This paper was accepted into the Technical Program but was not presented at the 2020 SEG Annual Meeting.
