High-precision velocity analysis method in prestack time domain and its application

Key words:  seismic prospecting  common scattering point  ellipse evolving  velocity analysis  prestack time migration

Abstract:

In a horizontally layered medium, the conventional velocity analysis and dip move-out correction methods cannot solve the problem of reflection point diffusion. The velocity analysis using high accuracy common scattering point gathers, however, can be a good solution. The ellipse evolving common reflection point velocity analysis method was used to get the velocity field as the initial input of the high accuracy of common scattering gathers velocity analysis method. The single-square root travel time equation of equivalent offset, extraction process of the common scattering point gathers velocity analysis method, and prestack time migration based on common scattering point gathers were also studied. Through a combination of two methods, velocity spectrums are greatly improved in the model and actual data. A high-precision velocity field is obtained, and the efficiency in the pre-stack time section is also improved.