Subsalt Steep Dip Imaging Study with 3D Acoustic Modeling

We present a 3D acoustic wave equation modeling study with the objective of understanding imaging challenges for steep dips (faults and three-way closure) beneath allochthonous salt sheets. Narrow-azimuth, wide-azimuth and full-azimuth surface acquisition configurations as well as a 3D vertical seismic profile (VSP), are simulated using a two-way acoustic finite-difference modeling algorithm and followed by reverse time migration (RTM). Modeling results show that even full-azimuth surface seismic is not able to image steeply dipping subsalt events associated with faults and three-way traps. Only a 3D VSP is able to image targeted subsalt steep dips by placing receivers below the salt. The imaging success of VSP in this study emphasizes its complementary role to surface seismic.