1. Jingfeng Zhang and Arthur B. Weglein
Application of Extinction Theorem Deghosting method on Ocean Bottom Data
Jingfeng Zhang and Arthur B. Weglein
M-OSRP annual meeting
University of Houston
May 10th –12th, 2006

2. Outline Background and Motivation Theory Numerical tests Conclusions
Acknowledgments

3. Background and Motivation
Most of conventional multiple, imaging and inversion algorithms:
Robust and low expectation
Inverse scattering series related (ISS) algorithms:
ISS free surface multiple removal
ISS internal multiple attenuation and elimination
Imaging without the velocity
Nonlinear inversion
(1) Chain; (2) Amplitude and arrival time

4. Background and Motivation
Benefits of Deghosting
Prerequisite for ISS FSMR
Eliminate angle-dependent ghost effect
Large angle AVO
Nonlinear inversion
Imaging without the velocity
Restoring amplitude spectrum, low frequency component:
Ghost notch

5. Background and Motivation
Advantage of Extinction Theorem deghosting:
Stable
No low frequency assumption

6. Review: Theory
Weglein et al. (2002)
F.S.
Pseudo-M.S.
M.S.
Earth

7. Review: Deghosting
H. Tan (1992) and A.Osen et al. (1998)

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

9. Review: Deghosting results
Red Solid: Exact results; Blue Dash: Calculated results

10. Review: FSMR results Red Solid: Before FSMR; Blue Dash: After FSMR
Using the 1st term in the ISS FSMR series

11. Ocean bottom data deghosting (Theory)
Weglein et al. (2002):
Using measured P and its derivative
Disadvantages:
Noise on geophone
Coupling issue and scale factor : actually measured are and

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

13. Advantages and Disadvantages
Avoid noise on geophone
Avoid coupling issue and scale factor : actually measured are and
Disadvantages:
Unstable spectral division

14. Ocean bottom data deghosting (Theory)
Assume there is no direct wave, then
(1) only calculate “good” points;
(2) interpolate others
is the receiver depth

15. Interpolation at unstable points

16. Interpolation at unstable points

17. Ocean bottom data deghosting (Theory)
Direct wave; (b) Primary; (c) Receiver ghost of primary;
(d) 1st order FSM; (e) Source-Receiver ghost of Primary
(f) Source ghost of the 1st order FSM

18. A note on FSMR
Primary
Primary*Primary
FSM
Weglein et al. (1997, 2003)

19. Procedure Receiver side deghosting Source side deghosting
Calculate using spectral division
Source side deghosting

20. Receiver ghost and Source-Receiver ghost
Primary and
its source ghost
Before deghosting
Receiver ghost and Source-Receiver ghost

21. After deghosting

23. Another procedure Receiver side deghosting Source side deghosting
Calculate using spectral division
Source side deghosting
Calculate using prediction in space domain

24. Deghosting (Theory)
H. Tan (1992) and A.Osen et al. (1998)

25. New procedure

26. Former procedure

27. Applying taper
at k_z=0 end

28. Conclusions
The provided OBC deghosting procedure has certain advantages and disadvantages.
In predicting the derivative of the field, avoid using spectral division gives better result.
Further effort is needed in order to remove all of the artifacts.

29. Requirements for the field data
Tower streamer data
REAL point receiver 3D survey
Good estimation of source wavelet radiation pattern
Ocean bottom data
REAL 3D survey
More work to remove artifacts

30. Acknowledgments
Kris Innanen and Ken Matson (BP) is thanked for helpful discussions.
The support of M-OSRP sponsors is much appreciated.