1. 4C Mahogony Data Processing and Imaging by LSMF Method
Jianhua Yu and Yue Wang

2. Outline Motivation and Objective LSMF Method
Examples Graben Model Mahogany Field Data
Summary

3. Outline Motivation and Objective LSMF Method
Examples Graben Model Mahogany Field Data
Summary

4. Geological Objectives
Image Complex Structure
Detect Gas Reservoir Over Salt

5. Problems Strong Guided Waves P-SV Conversion at Reflector ?
How to Get “Pure” P-P and P-SV
Strong Guided Waves

6. Problems for F-K Use only wave moveout Strong guided waves
Near offset distortion

7. P-P and P-SV Waves
Source
P-P
P-SV
Point Scatterer

8. Least Squares Migration Filtering
Moveout
Particle Motion
Direction
Time +
offset
Separation

9. Separate P-P & P-S Suppress Guide Waves Improve Migration Image
Objective
Separate P-P & P-S
Suppress Guide Waves
Improve Migration Image

10. Outline Motivation and Objective LSMF Method
Examples Graben Model Mahogany Field Data
Summary

11. LSMF with Moveout m p = L m = [ Lp Lps ] m m [L L] L d m = moveout PS-1 T = m ps PS P

12. LSMF with Moveout+2-Comp.
Particle Motion P PS q
(cos q , sin q )
(sin q , -cos q )
u = u + u p ps
v = v + v
total
2-component particle
motion data
p = L m = [ Lp Lps ] m p ps
Scalar
moveout m
u = [ cos(q)Lp sin(q) Lps ] p ps
Vector
moveout
+ particle motion
v = [ sin(q)Lp -cos(q) Lps ]

13. LSMF Method = > Dpp + Dp-s Lpp mpp P-P wave Time Lp-s mp-s P-S wave
Observed data
Dp-s
Lp-s mp-s
Lpp mpp
Reflectivty
Modeling
Operator
P-P wave
Time
P-S wave
Offset

14. LSMF Filtering Step dpp = Lppmpp dp-s = Lp-smp-s P-P wave Time Time
P-S wave
Offset
Time
P-P wave
Offset
Time

15. LSMF Method
Operators are constructed based on moveout and particle-motion direction
The migration operators are the transposes of the modeling operators

16. Outline Motivation and Objective LSMF Method
Examples Graben Model Mahogany Field Data
Summary

17. Examples
Graben Model
Mahogony Field Data

18. Graben Velocity Model 5000 X (m) Depth (m) 3000 V1=2000 m/s
X (m)
V1=2000 m/s
V2=2700 m/s
V3=3800 m/s
Depth (m)
V4=4000 m/s
V5=4500 m/s
3000

19. FD Synthetic Data P-P P-S P-S P-P Horizontal Component
Offset (m)
Offset (m)
5000
5000
P-P
P-S
Time (s)
P-S
P-P
1.4
Horizontal Component
Vertical Component

20. LSMF Separation P-P P-S Horizontal Component Vertical Component
Offset (m)
5000
Offset (m)
5000
P-P
P-S
Time (s)
1.4
Horizontal Component
Vertical Component

21. F-K Filtering Separation
Offset (m)
5000
Offset (m)
5000
P-S
P-P
Time (s)
P-S
P-P
1.4
Horizontal Component
Vertical Component

22. Test Results Indicate:
LSMF works well for separating
P-P and P-SV
LSMF is superior to F-K filtering

23. Examples
Graben Model
Mahogony Field Data

24. Acquisition Survey
Shot Line
OBC
9 km
29 km

25. Main Processing Flow Geometry assignment, datuming and so on
Trace edit, noise elimination, dual-sensor summation
Amplitude Recovery
Static correction, (F-K filtering), multiple suppression
LSMF, velocity analysis
Migration
Output

26. Raw CSG Hydrophone component Vertical component Offset(m) Offset(m)
-750
725
-750
725
Continuous events
Continuous events
Time (s) 4
Hydrophone component
Vertical component

27. Raw CSG Radial component Transverse component Offset(m) Offset(m)
-750
725
-750
725
Wormy events
Wormy events
Time (s) 4
Radial component
Transverse component

28. Raw CRG Hydrophone component Vertical component X (m) X (m) Time (s)
3750
3750
Continuous events
Continuous events
Time (s) 4
Hydrophone component
Vertical component

29. Raw CRG Radial component Transverse component X (m) X (m) Time (s)
3750
3750
Continuous events
Continuous events
Time (s) 4
Radial component
Transverse component

30. Rough Estimate of Static Shift
Source
Receiver 12 p s
Receiver static
Static shift (ms)
Source
Receiver p s
Shot static -4
100
Station Number

31. Data Analysis Indicates:
The Shear static shifts exist
These shifts mainly come from receivers and one-way Shear path from deeper reflector
P-S waves originate from reflectors

32. CRG1 Data before Using LSMF
Guided wave and P-S
Time (s) 4
CRG1 (Vertical component)

33. CRG1 Data after Using F-K Filtering
Unwanted waves remain
Time (s) 4
CRG1 (Vertical component)

34. CRG1 Data after Using LSMF
Less Noise remains
Time (s) 4
CRG1 (Vertical component)

35. Prestack Migration Image With F-K Separation
Midpoint (Km)
4.6 c
Time (s)
3.5

36. Prestack Migration Image With LSMF Separation
Midpoint (Km)
4.6 c
Time (s)
3.5

37. A Zoom View of Box A Time (s) Midpoint (Km) Midpoint (Km) FK+Mig.
0.6
1.4
0.6
1.4
2.0
Time (s)
3.2
FK+Mig.
LSMF+Mig.

38. A Zoom View of Box C Time (s) Midpoint (Km) Midpoint (Km) FK+Mig.
3.4
4.6
3.4
4.6
0.2
Time (s)
0.8
FK+Mig.
LSMF+Mig.

39. Outline Motivation and Objective LSMF Method
Examples Graben Model Mahogany Field Data
Xwell Data
Summary

40. SSP Synthetic

41. Xwell

42. Outline Motivation and Objective LSMF Method
Examples Graben Model Mahogany Field Data
Summary

43. Summary and improves the migration image P-SV waves in Mahogony data
originate from the deep reflectors
LSMF gives better separation results
and improves the migration image

44. Summary LSMF can eliminate unwanted noise, such as guided waves
LSMF has negative impact on the
fidelity of data to some extent

45. Summary Future Research: Multiple Elimination Prestack Depth Migration
Converted Wave Imaging

46. Acknowledgement We are grateful to the 1999 sponsors
of the UTAM consortium for financial support