1. Deghosting of towed streamer and OBC data
                                           
Jingfeng Zhang, Arthur B. Weglein
M-OSRP Annual Meeting,
University of Houston
March 31 – April 1, 2004

2. Outline Motivation Theory overview Towed streamer deghosting
Theory and strategy
Numerical tests
Ocean bottom deghosting
Conclusions and plans
Acknowledgements

3. Motivation Towed streamer deghosting Conventional methods
New techniques
Ocean Bottom deghosting

4. M-OSRP projects Wavelet estimation Deghosting
Interpolation and extrapolation
3-D multiple attenuation
Inverse scattering sub series for imaging
Inverse scattering sub series for inversion

5. Theory Overview
Weglein et al. (2002)
F.S.
M.S.
earth

6. Note (1)

7. Green’s Second Identity
Note (2)
Green’s Second Identity

8. Note (3) Deghosting formula Eq. (1) Weglein et al. (2002) earth F.S.
M.S.
Weglein et al. (2002)
earth

9. Note (4) Field prediction Eq. (2) Scattered field prediction Eq. (3)
F.S.
H. Tan (1992) and A.Osen et al. (1998)
M.S.
Scattered field prediction Eq. (3)
earth
H. Tan (1999), Weglein et al. (2000)

10. Note (5) Wavelet estimation Eq. (4) Weglein and Secrest, (1990) earth
F.S.
Wavelet estimation Eq. (4)
Weglein and Secrest, (1990)
M.S.
earth

11. Notes conclusion

12. Towed streamer deghosting (Theory)
Weglein et al. (2002)
F.S.
Pseudo-M.S.
M.S.

13. Towed streamer deghosting (Theory)
H. Tan (1992) and A.Osen et al. (1998)
H. Tan (1999), Weglein et al. (2002)

14. Towed streamer deghosting (Theory)
K=0.3 (f~72Hz)
Pseudo-M.S.

15. Towed streamer deghosting (Theory)

16. Towed streamer deghosting (Theory)
(2)
(3)

17. Towed streamer deghosting (Theory)
Offset x (m)
Exact A(w)=1.0

18. Towed streamer deghosting (Numerical tests)
F.S.
(0,2)
6.0m
M.S.
300m
c1=1500m/s
c2=2250m/s

19. Ricker wavelet

20. Total data received
At (1500,6.0)
At (0,6.0)

21. Wavelet approximation

26. Wavelet approximation

31. Depth sensitivity K=0.3 (f~72Hz) Pseudo-M.S.
A1(w)=(2,3),A2=0.04*A1,A3=0.03*A1,A4=0.3*A1
Pseudo-M.S.

32. Red solid: Exact Up-going P (5.8m)
Blue dash: Predicted Up-going P (6.3m) (using wrong depth 6.5m)

33. Red solid: Exact Up-going P (5.8m)
Blue dash: Predicted Up-going P (6.3m) (using wrong depth 6.5m)

34. Red solid: Exact Up-going P (5.8m)
Blue dash: Predicted Up-going P (6.3m) (using wrong depth 6.5m)

35. Red solid: Exact Up-going P (5.8m)
Blue dash: Predicted Up-going P (6.3m) (using wrong depth 6.5m)

36. Ocean bottom data deghosting (Theory)
Weglein et al. (2002)
Both and (particle velocity) are measured.
Noise on geophone
Coupling issue and scale factor : actually measured are and

37. Ocean bottom data deghosting (Theory)
Troublesome and historic
impediment measurement
Two stable measurements
Triangle relationship
Wavelet estimation Weglein and Secrest, (1990)

38. Ocean bottom data deghosting (Theory)
In this procedure:
Using and A(w) to calculate
Deghosting

39. Conclusions for towed streamer deghosting
If source wavelet is available, the deghosting algorithm performs well, as expected.
With an approximate wavelet, the algorithm still works well. If the rough duration of the source wavelet is known, very good deghosting result can be obtained.
Field data test is planned for 2004.

40. Plans and Acknowledgements
Numerical tests on the proposed procedure for ocean bottom deghosting using both synthetic and ocean bottom cable field data.
We thank M-OSRP sponsors for supporting this project.
Special thanks to Nizar Chemingui and Jon Sheiman for their interests. We thank A. de-Hoop for providing references and Hing Tan for valuable discussions.