Method for modeling velocity model of geologic structure

Abstract

The invention provides a method for modeling a velocity model of a geologic structure, which is characterized by comprising the steps of performing stacking velocity analysis on a common midpoint gather to obtain stacking velocity; obtaining a layer plane graph of every layer of a wave impedance interface according to the stacking velocity; generating a root-mean-square velocity body by means of the stacking velocity; obtaining root-mean-square velocity of every layer by means of the generated layer plane graphs and the generated root-mean-square velocity body; obtaining initial layer velocity of every layer according to the obtained root-mean-square velocity by controlling velocity inversion; converting a time domain of layer information of every layer into a depth domain by utilizing the initial layer velocity and the graph migration technique to obtain layer information of the deep domain of every layer; and obtaining a first velocity model by utilizing the initial layer velocity of every layer and the layer information of the deep domain of every layer.

Description

technical field [0001] The invention relates to the field of geophysical prospecting, in particular, to a modeling method for a velocity model of a high-steep complex geological structure. Background technique [0002] Under the condition of steep and complex structure, the correct imaging of subsurface medium can only be obtained by prestack depth migration from artificial seismic data. However, prestack depth migration can only be imaged correctly if the velocity model is accurate. Where prestack depth migration is required, conventional velocity analysis methods often fail to meet the desired accuracy requirements. In this case, in order to obtain a more accurate velocity model, a velocity analysis method based on migration iteration was developed. Now it can be said that migration velocity analysis is velocity analysis using migration iteration. This type of velocity analysis method uses the influence of velocity field on migration imaging to modify the velocity model....

AI Technical Summary

Problems solved by technology

However, there is a large difference between the average velocity and the RMS velocity when the velocity varies laterally

This will cause the divergence of the velocity iteration process. Therefore, when many complex structures and velocity lateral changes exist, the accuracy and stability of the method will be affected. Its basic assumption limits its application to the situation where the stratum is a horizontal layer or the underground structure is relatively simple. This limits the application of the method to some extent

The common disadvantages of these methods are that they are not suitable for lateral drastic changes in velocity and inclined stratigraphic structures.

Images