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.