The
Permian Formation has developed giant thick salt domes in the Block M, Pre-Caspian
Basin. Because of the huge velocity difference between the salt domes and
surrounding rocks, the sub-salt seismic events are pulled up in time sections
and displays structure artifacts, which brings difficulty in well deployment.
Based on analyzing the characteristics of the velocity and the difficulties in
the variable-velocity mapping of saliferous basins, the authors firstly
edited the anomalies in seismic stack velocity spectrum, then calculated the
layer velocity through coherent inversion and optimized the velocity field
combined with logging data. Finally, we carried out time-depth conversion and
structure mapping by using map migration method. By using the above workflow, the
structure map of Block M was obtained, and the impact of salt-dome velocity was
removed, which displays the actual shape of sub-salt structure.