The conventional tomographic inversion calculates the depth errors based on residual curvatures of gathers and ignores the accu-mulation of depth errors from top to bottom.Cumulative error increases with depth,which affects depth positions of horizons on prestack depth migration profiles obtained using the updated velocity field.Based on the principle of curvature depth error accumulation,a recursive equation is formulated to eliminate cumulative errors layer by layer from bottom to top,and horizon picking is updated according to depth residuals.Residual time differences are calculated by using the residual curvatures of common imaging-point gathers in the angle domain,and the relation between incident angle and interval velocity derived from the Snell's law is used to calculate incident angles and eliminate cumulative errors for horizon updating.Model tests and field data application prove the feasibility and effectiveness of the proposed method.Compared with conventional tomographic inversion methods,the new method effectively improves the overall accuracy and efficiency to in-vert the velocity model for subsequent prestack depth migration.
tomographic inversionresidual time differencecumulative errorADCIGsmigrationhorizon updating
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