Diving Wave Tomography and Reflection Tomography for PSDM Velocity Model Building of Complex Depth Imaging in Loess Tableland Area of Western Edge of Ordos Basin

To solve the problem of complex structures under complicated surface conditions in the loess plateau of the western edge of Ordos Basin, a practical prestack depth migration velocity modeling method was developed by using shallow layer diving wave tomography (DWT) and deep layer reflecting wave tomography. First generate a starting near-surface velocity based on drilling and interpret information, secondly diving wave tomographic inversion is used to establish initial near-surface model, with the regular treatment of deep velocity model matching, set up the initial irregular surface velocity model, and then on the basis of grid reflection wave tomography, after iterative rounds, finally obtained the reliable and high precision velocity model. The imaging processing of seismic data in the MJT work area on the western margin of Ordos Basin has verified the effectiveness of this set of velocity modeling technology, and the imaging of underground structure is more reasonable and accurate.