1. HOCIGs and VOCIGs via Two-way Reverse Time Migration
William Symes, Fuchun Gao
Rice University
TRIP
Oct 29, 2004

2. Outline Common image gathers (offset domain) Conclusions 1. Theory
2. HOCIGs and VOCIGs--- examples
Conclusions

3. Two-way Reverse Time Migration
1. Forward propagation: finite difference solution to
acoustic equation by
where
: impedance matrix.
: seismic wave field vector.
: source vector.
The acoustic wave equation is solved in frequency-space domain.
Pratt et al.(1998)

4. Two-way Reverse Time Migration
2. Back-propagation of data
3. Horizontal offset image (frequency domain)
Vertical offset image (frequency domain)
Common image gathers (time domain):
where
: recorded wave fields : back-propagated waves
: source location : image location
( : complex conjugate)
The inversion problem is solved by gradient method.

5. Example 1
No. of source = 51
No. of receiver = 51
Source interval =10m
Receiver interval=10m

6. Frequency domain CIGs

7. Frequency domain CIGs, tapered

8. time domain CIGs

9. Example 2
No. of source =101
No. of receiver = 101
Source interval =1.5m
Receiver interval=1.5m

10. Time domain
Frequency domain HOCIGs

11. Example 3

12. VOCIGs

13. HOCIG
Filtered HOCIG