Multiple attenuation

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Multiple attenuation

• Why preserve receiver ghosts of primaries?

Water surface
Receiver
Reflector
Rp
Rg
The subsurface aperture of the receiver ghosts of
primaries (Rg) is larger than the subsurface
aperture of primaries (Rp) themselves.
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Model 2 (non-flat sea-floor)
Vp1.50 km/s Vs0.00 km/s
Vp2.00 km/s Vs 1.15 km/s
Vp3.00 km/s Vs 1.55 km/s
Vp3.00 km/s Vs 1.55 km/s
Vp2.60 km/s Vs 1.30 km/s
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VC data (two cables)
1
134
of receivers
0.0
0.0
0.5
0.5
1.0
1.0
Time (s)
1.5
1.5
2.0
2.0
2.5
2.5
3.0
3.0
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First order multiple with VC containing direct
wave
First order multiple with VC without direct wave
Difference (receiver ghosts)
Streamer with multiples
D1
D1
D1-D1
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First order multiple with VC containing direct
wave
First order multiple with VC without direct wave
Difference (receiver ghosts)
Streamer without multiples
D1
D1
D1-D1
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PHILLIPS Dataset
Shot lines
VC
1
5
791
795
i
793
797
3
7
Number of shots 797 In-line shot
spacing 50 m Cross-line shot spacing 75
m
VC2
VC4
c
VC3
VC1
792
2
6
4
8
794
796
VC3
VC1
VC2
VC4
0
200
Number of vertical cables 4 Number of
receivers/cable 16 Receiver spacing
25 m Vertical cable spacing 2 km
400
Depth (m)
600
800