Common-offset migration of DMO-corrected data

Seismic Data Analysis

Series	Investigations in Geophysics
Author	Öz Yilmaz
DOI	http://dx.doi.org/10.1190/1.9781560801580
ISBN	ISBN 978-1-56080-094-1
Store	SEG Online Store

This technique for migration velocity analysis is the basis for the most common sequence used for prestack time migration (prestack time migration). A flowchart for the method is shown in Figure 5.4-4.

Figure 5.4-4  A flowchart of an algorithm for common-offset migration of DMO-corrected data.

1. Starting with prestack data P(y, h, t) in coordinates of midpoint y, offset h, and two-way event time t in the unmigrated position, apply NMO correction using an initial velocity field with minimal dip effect.
2. Sort the normal-moveout corrected data P(y, h, t_n) to common-offset sections P(y, t_n; h).
3. To each common-offset section P(y, t_n; h), apply DMO correction P(y, τ₀; h).
4. Migrate each of the common-offset sections using a zero-offset migration algorithm (migration) and the velocity field based on the flat-event velocity picks from step (a).
5. Sort the migrated common-offset data P(y, τ; h) back to CMP gathers P(y, h, τ) and apply inverse NMO correction using the flat-event velocities from step (a).
6. Perform velocity analysis at frequent intervals as needed to derive an optimum velocity field which is used for the subsequent migration of the data.

See also

• Prestack Stolt migration
• Prestack Kirchhoff migration
• Velocity analysis using common-reflection-point gathers
• Focusing analysis
• Fowler’s velocity-independent prestack migration

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