A Method and Device for Analyzing Migration Velocity of Variable Offset vsp Kirchhoff

Abstract

The present invention discloses a variable offset VSP Kirchhoff migration velocity analysis method and device. The method includes the following steps: S1. Input the initial 2-dimensional depth velocity model of the variable offset VSP, the initial variable offset VSP Kirchhoff prestack time migration common imaging gathers, initial Kirchhoff prestack time migration imaging sections of variable offset VSP, migration velocity analysis horizons, residual curvature of common imaging gathers of migration velocity analysis horizons; S2. Utilize the 2D depth-velocity model and migration velocity analysis tomography of VSP with variable offset distance, and use ray tracing to calculate formation dip, incident angle, and ray path; S3. Co-imaging with Kirchhoff pre-stack time migration with VSP with variable offset The linear tomographic equation is established from the residual curvature of the gather, and the least square solution is used to obtain the velocity disturbance, and the 2D depth velocity model is updated. The invention utilizes Kirchhoff pre-stack time migration co-imaging gather residual curvature to update the migration velocity, makes the co-imaging gather straight and improves the imaging quality.

Description

technical field [0001] The invention relates to seismic data velocity analysis, in particular to a VSP Kirchhoff migration velocity analysis method and device with variable offset distance. Background technique [0002] Variable offset distance VSP (Walkaway VSP) means that an array composed of multiple geophones is placed in the observation well, and a shot line composed of artificially excited multiple shot points is laid on the surface, which is a two-dimensional observation method of VSP; Under the condition of manually stimulating seismic data at points, data acquisition in VSP wells with variable offset distance is realized. The three-dimensional diagram of the acquisition system is as follows: figure 1 As shown; VSP acquisition with variable offset is actually data acquisition by the geophones at each receiver point when each shot point is excited; VSP with variable offset can observe reflected longitudinal waves and reflected converted shear waves, and use offset ima...

AI Technical Summary

Problems solved by technology

[0004] However, the existing migration velocity analysis methods are mainly aimed at the observation method of surface earthquakes, and the migration velocity analysis formula of surface earthquakes is not suitable for borehole earthquakes

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