SLIDE 1
- M-OSRP: objectives, strategy and game-changing delivery
- Recent advances to on-shore, ocean bottom and towed
streamer preprocessing for deghosting and ground roll removal
Jing Wu and Arthur B. Weglein
University of Houston February 7, 2017 Houston, TX
SLIDE 2 Migration
– Post-stack time – Post-stack depth – Pre-stack time – Pre-stack depth – RTM
- As migration became more capable there was a commensurate increase
in the need for an accurate velocity model
2
SLIDE 3 Multiple removal
– Predictive deconvolution – Stacking – FK filter – Radon – Model and Subtraction – SRME + Feed back loop (Delphi)
- As multiple removal became more capable there was a commensurate
increase in the need for accurate subsurface information
3
SLIDE 4
- ISS free surface and internal multiple removal had a game-changing
impact on multiple elimination.
- ISS direct depth imaging without a velocity model will have a game-
changing impact on structural imaging and amplitude analysis.
4
SLIDE 5
Projects, goals and deliverables within M-OSRP
v Preprocessing for on-shore, OBS, and towed streamer acquisition v Multiple elimination for surgically removing multiples that interfere with target and reservoir primaries v More effective migration and direct inversion velocity analysis v Game changing migration, direct and without a velocity model
5
SLIDE 6
Projects, goals and deliverables within M-OSRP
v Preprocessing for on-shore, OBS, and towed streamer acquisition v Multiple elimination for surgically removing multiples that interfere with target and reservoir primaries v More effective migration and direct inversion velocity analysis v Game changing migration, direct and without a velocity model
6
SLIDE 7 Preprocessing for on-shore, OBS, and towed streamer acquisition
- Developing and delivering new and more effective methods for the essential
preprocessing steps (that in addition to their intrinsic value) are necessary prerequisites for the new high-end and most effective methods for eliminating free surface and internal multiples , and that subsequently depth image and invert primaries. Those prerequisites include: removing ground roll and preserving reflection data at all offsets, and source and receiver de- ghosting for towed streamer, on-shore and ocean bottom acquisition, accommodating both flat horizontal and non-flat acquisition surfaces.
7
SLIDE 8
Projects, goals and deliverables within M-OSRP
v Preprocessing for on-shore, OBS, and towed streamer acquisition v Multiple elimination for surgically removing multiples that interfere with target and reservoir primaries v More effective migration and direct inversion velocity analysis v Game changing migration, direct and without a velocity model
8
SLIDE 9 Multiple elimination for surgically removing multiples that interfere with target and reservoir primaries
- Developing and delivering the next generation of urgently needed multiple
removal capability, with the elimination of free surface and internal multiples, without depending on energy minimization adaptive subtraction.
- Accurately predicting and surgically removing a multiple that interferes with a
target or reservoir primary, and with the unique ability to not damage the target or reservoir primary. The latter interference between a multiple and target primary can frequently occur on shore and often off-shore, as well. That next generation of capability will only be delivered by M-OSRP and for many sponsors that project and delivery is the business driver and ROI.
9
SLIDE 10
Projects, goals and deliverables within M-OSRP
v Preprocessing for on-shore, OBS, and towed streamer acquisition v Multiple elimination for surgically removing multiples that interfere with target and reservoir primaries v More effective migration and direct inversion velocity analysis v Game changing migration, direct and without a velocity model
10
SLIDE 11 More effective migration and direct inversion velocity analysis
- Progressing and delivering the first migration method for heterogeneous
media that is equally effective at all frequencies at the target and reservoir. It provides improved structural resolution and amplitude analysis, compared to all current migration methods including RTM. The documented codes for a 2D and 3D heterogeneous subsurface will be delivered in 2017. This new and more effective migration will require a velocity model and we will progress a direct non-linear inverse scattering series method for velocity analysis as an alternative to all current indirect velocity analysis methods, for example, CIG flatness and FWI.
11
SLIDE 12
Projects, goals and deliverables within M-OSRP
v Preprocessing for on-shore, OBS, and towed streamer acquisition v Multiple elimination for surgically removing multiples that interfere with target and reservoir primaries v More effective migration and direct inversion velocity analysis v Game changing migration, direct and without a velocity model
12
SLIDE 13 Game changing migration, direct and without a velocity model
- The direct inverse scattering series (ISS) depth imaging without a velocity
model will be progressed and delivered as a tool box option. In contrast to
- ther new approaches to migration, for example, Interferometry and
Marchenko imaging, that require a velocity model, the ISS direct imaging method is the only imaging method that is direct and doesn’t require a macro-velocity model or any other subsurface information.
13
SLIDE 14
- ISS free surface and internal multiple removal had a game-changing
impact on multiple elimination.
- ISS direct depth imaging without a velocity model will have a game-
changing impact on structural imaging and amplitude analysis.
14
SLIDE 15
Projects, goals and deliverables within M-OSRP
v Preprocessing for on-shore, OBS, and towed streamer acquisition v Multiple elimination for surgically removing multiples that interfere with target and reservoir primaries v More effective migration and direct inversion velocity analysis v Game changing migration, direct and without a velocity model
15
SLIDE 16
Recent advances in separating the reference wave and preserving reflection data, and for deghosting, for towed streamer, on-shore and ocean bottom acquisition: implications for multiple removal, structural determination and amplitude analysis
Jing Wu and Arthur B. Weglein
University of Houston February 7, 2017 Houston, TX
SLIDE 17
Historic contributions to Green’s theorem based processing
17
SLIDE 18
Historic contributions to Green’s theorem based processing
18
v Migration
Schneider 1978
SLIDE 19
Historic contributions to Green’s theorem based processing
19
v Reference and scattered wave separation & Source signature estimation
Weglein & Secrest 1990
v Migration
Schneider 1978
SLIDE 20
Historic contributions to Green’s theorem based processing
20
v Reference and scattered wave separation & Source signature estimation
Weglein & Secrest 1990
v Migration
Schneider 1978 Earth F.S. Air Water Reference wave
SLIDE 21
Historic contributions to Green’s theorem based processing
21
v Reference and scattered wave separation & Source signature estimation
Weglein & Secrest 1990
v Reduce data requirement in marine
Osen et al. 1998, Tan 1999
v Migration
Schneider 1978
SLIDE 22
Historic contributions to Green’s theorem based processing
22
v Reference and scattered wave separation & Source signature estimation
Weglein & Secrest 1990
v Reduce data requirement in marine
Osen et al. 1998, Tan 1999
v Deghosting
Weglein 2002, J. Zhang & Weglein 2005, 2007
v Migration
Schneider 1978
SLIDE 23
Historic contributions to Green’s theorem based processing
23
v Reference and scattered wave separation & Source signature estimation
Weglein & Secrest 1990
v Reduce data requirement in marine
Osen et al. 1998, Tan 1999
v Deghosting
Weglein 2002, J. Zhang & Weglein 2005, 2007
v Field data examination to deghosting method
Mayhan & Weglein 2013
v Migration
Schneider 1978
SLIDE 24 Historic contributions to Green’s theorem based processing
24
v Remove ground roll onshore
v Reference and scattered wave separation & Source signature estimation
Weglein & Secrest 1990
v Reduce data requirement in marine
Osen et al. 1998, Tan 1999
v Deghosting
Weglein 2002, J. Zhang & Weglein 2005, 2007
v Field data examination to deghosting method
Mayhan & Weglein 2013
v Migration
Schneider 1978
SLIDE 25
Progress
vDeghosting data on a depth variable cable vWave separation onshore for the removal of ground roll and ghosts vDeghosting data at the ocean bottom
25
SLIDE 26
26
General theory of Green’s theorem wave separation
= 𝜍$𝐻&
' + 𝜍)𝐻& '
𝝇𝟐 𝝇𝟑
SLIDE 27 27
General theory of Green’s theorem wave separation
= 𝜍$𝐻&
' + 𝜍)𝐻& ' 𝐻&
': Causal Green’s function in the homogeneous whole world
𝝇𝟐 𝝇𝟑
SLIDE 28 28
General theory of Green’s theorem wave separation
𝑠 ⃑ = 𝜍$𝐻&
' + 𝜍)𝐻& '
𝝇𝟐 𝝇𝟑
𝐻&
': Causal Green’s function in the homogeneous whole world
SLIDE 29 29
General theory of Green’s theorem wave separation
P2
𝑠 ⃑
P1
𝑄 = 𝑄
$ + 𝑄)
= 𝜍$𝐻&
' + 𝜍)𝐻& '
𝝇𝟐 𝝇𝟑
𝐻&
': Causal Green’s function in the homogeneous whole world
SLIDE 30 30
General theory of Green’s theorem wave separation
𝑄) 𝑠 ⃑, 𝜕 = 2 𝑄𝛼′𝐻&
' − 𝐻& '𝛼′𝑄 6 𝑜
8𝑒𝑇′
;<
P2 S’
𝑠 ⃑ 𝑄 = 𝑄
$ + 𝑄)
= 𝜍$𝐻&
' + 𝜍)𝐻& '
𝝇𝟐 𝝇𝟑
𝐻&
': Causal Green’s function in the homogeneous whole world
SLIDE 31 Marine experiment
31
Water
M.S.(Cable) F.S. O.B.
Air Earth
F.S. free surface, or air/water boundary O.B.
M.S. measurement surface
SLIDE 32
Homogeneous whole-space of water
32
Water
SLIDE 33
𝝇𝟐: Air gun
33
Water 𝝇𝟐
SLIDE 34
𝝇𝟑: Air perturbation
34
Water Air
F.S.
𝝇𝟑 𝝇𝟐
SLIDE 35
𝝇𝟒: Earth perturbation
35
Water Air Earth
F.S. O.B.
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 36
Predict a portion of total wave at 𝑠 ⃑ contributed by 𝝇𝟒
36
Water Air Earth
F.S. O.B.
S’
𝑠 ⃑ 𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 37
Predict a portion of total wave at 𝑠 ⃑ contributed by 𝝇𝟒
37
Water Air Earth
F.S. O.B.
S’
𝑠 ⃑
Up
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 38
Predict a portion of total wave at 𝑠 ⃑ contributed by 𝝇𝟒
38
Water Air Earth
F.S. O.B.
S’
𝑠 ⃑
Up Down Down
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 39
Predict deghosted data at 𝑠 ⃑ contributed by 𝝇𝟒
39
Water Air Earth
F.S. O.B.
S’
𝑠 ⃑ 𝝇𝟑 𝝇𝟐 𝝇𝟒
Deghosted
SLIDE 40
Predict deghosted data at 𝑠 ⃑ contributed by 𝝇𝟒
40
Water Air Earth
F.S. O.B.
𝑠 ⃑
S’
𝝇𝟑 𝝇𝟐 𝝇𝟒
Deghosted
SLIDE 41
Predict deghosted data at 𝑠 ⃑ contributed by 𝝇𝟒
41
Water Air Earth
F.S. O.B. M.S.(Cable)
𝑠 ⃑
Deghosted
S’
𝑄>? 𝑠 ⃑, 𝜕 = @ 𝑄𝛼′𝐻&
' − 𝐻& '𝛼′𝑄 6 𝑜
8𝑒𝑇′
A.C.
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 42 Advantage 1
42
Water Air Earth
F.S. O.B. M.S.(Cable)
𝑠 ⃑
Deghosted
- Can accommodate cable with an arbitrary shape
(Z. Zhang & Weglein, 2016) 𝑄>? 𝑠 ⃑, 𝜕 = @ 𝑄𝛼′𝐻&
' − 𝐻& '𝛼′𝑄 6 𝑜
8𝑒𝑇′
A.C.
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 43 Advantage 1
43
Water Air Earth
F.S. O.B. M.S.(Cable)
𝑠 ⃑
Deghosted
- Can accommodate cable with an arbitrary shape
(Z. Zhang & Weglein, 2016) 𝑄>? 𝑠 ⃑, 𝜕 = @ 𝑄𝛼′𝐻&
' − 𝐻& '𝛼′𝑄 6 𝑜
8𝑒𝑇′
A.C.
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 44 Advantage 1
44
Water Air Earth
F.S. O.B. M.S.(Cable)
𝑠 ⃑
Deghosted
- Can accommodate cable with an arbitrary shape
(Z. Zhang & Weglein, 2016) 𝑄>? 𝑠 ⃑, 𝜕 = @ 𝑄𝛼′𝐻&
' − 𝐻& '𝛼′𝑄 6 𝑜
8𝑒𝑇′
A.C.
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 45 Advantage 1
45
- Can accommodate cable with an arbitrary shape
(Z. Zhang & Weglein, 2016)
E method that assumes cable
being horizontal
Water Air Earth
F.S. O.B. M.S.(Cable)
𝑠 ⃑
Deghosted
𝑄>? 𝑠 ⃑, 𝜕 = @ 𝑄𝛼′𝐻&
' − 𝐻& '𝛼′𝑄 6 𝑜
8𝑒𝑇′
A.C.
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 46 Advantage 2
46
- Needs no information about the “sources”:
ü wavelet, radiation pattern ü air property (shape and reflection at sea surface) ü earth property
𝑄>? 𝑠 ⃑, 𝜕 = @ 𝑄𝛼′𝐻&
' − 𝐻& '𝛼′𝑄 6 𝑜
8𝑒𝑇′
A.C.
Water Air Earth
F.S. O.B. M.S.(Cable)
𝑠 ⃑
Deghosted
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 47 Advantage 2
47
- Needs no information about the “sources”:
ü wavelet, radiation pattern ü air property (shape and reflection at sea surface) ü earth property
𝑄>? 𝑠 ⃑, 𝜕 = @ 𝑄𝛼′𝐻&
' − 𝐻& '𝛼′𝑄 6 𝑜
8𝑒𝑇′
A.C.
Water Earth
F.S. O.B. M.S.(Cable)
𝑠 ⃑
Deghosted
Air
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 48
Progress
vDeghosting data on a depth variable cable vWave separation onshore for the removal of ground roll and ghosts vDeghosting data at the ocean bottom
48
SLIDE 49 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Issue of current Green’s theorem deghosting method
49
Water Air Earth
F.S. O.B. M.S.(Cable)
𝑠 ⃑
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 50 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Issue of current Green’s theorem deghosting method
50
Water Air Earth
F.S. O.B.
𝑠 ⃑
M.S.(Cable)
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 51 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Issue of current Green’s theorem deghosting method
51
- Can only output deghosted data at a depth
above cable (Weglein et al., 2013)
𝑄>? 𝑠 ⃑, 𝜕 = @ 𝑄𝛼′𝐻&
' − 𝐻& '𝛼′𝑄 6 𝑜
8𝑒𝑇′
A.C.
Water Air Earth
F.S. O.B.
𝑠 ⃑
M.S.(Cable)
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 52 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
How to deghost the actual acquired data?
52
Water Air Earth
F.S. O.B. M.S.(Cable)
𝑠 ⃑
𝝇𝟑 𝝇𝟐 𝝇𝟒
E if cable being horizontal
SLIDE 53 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
E if cable being horizontal
- A new method without assuming cable being
horizontal (J. Wu & Weglein, 2016)
How to deghost the actual acquired data?
53
Water Air Earth
F.S. O.B.
𝑠 ⃑
M.S.(Cable)
𝝇𝟑 𝝇𝟐 𝝇𝟒
SLIDE 54 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
The new method
54
Step 1:
Deghost data at a depth (at E.S.) above cable
Use current Green’s theorem deghosting
(Weglein 2002, J. Zhang & Weglein 2007) Water Air Earth
F.S. O.B.
E.S.
𝑸𝒗𝒒 (output) 𝑸, 𝑸𝒐 (input)
𝝇𝟑 𝝇𝟐 𝝇𝟒
M.S.(Cable) E.S. evaluation surface, shallower than cable
SLIDE 55 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
The new method
55
Step 2:
Predict deghosted data right on the cable
Use Green’s theorem one-way wave prediction
(Weglein et al., 2011a,b, 2016) Water Air Earth
F.S. O.B.
E.S.
𝑸𝒗𝒒 (input) 𝑸𝒗𝒒 (output)
𝝇𝟑 𝝇𝟐 𝝇𝟒
M.S.(Cable)
SLIDE 56 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Numerical test: Model
56
Layer Velocity (m/s) Density (kg/m3)
Water 1500 1000 Earth 2500 1000
Water F.S. O.B. Earth
0m 300m
M.S.
10m 40m
SLIDE 57 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Numerical test: Model
57 Water F.S. O.B. Earth
0m 300m
M.S.
10m 40m
E.S.
25m
Layer Velocity (m/s) Density (kg/m3)
Water 1500 1000 Earth 2500 1000
SLIDE 58 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Input total 𝑄 at cable
58
0.2 0.4 0.6 0.8 Time/s
500 1000 Offset/m
0.5 1.0 x105
E.S. cable
SLIDE 59 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Input total 𝑄 at cable
59
0.2 0.4 0.6 0.8 Time/s
500 1000 Offset/m
0.5 1.0 x105
Primary
E.S. cable
SLIDE 60 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Input total 𝑄 at cable
60
0.2 0.4 0.6 0.8 Time/s
500 1000 Offset/m
0.5 1.0 x105
Primary Direct Receiver-ghost
E.S. cable
SLIDE 61 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Deghosted 𝑄 at E.S. (Step 1)
61
0.2 0.4 0.6 0.8 Time/s
500 1000 Offset/m
0.5 1.0 x105
Primary
E.S. cable
SLIDE 62 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Input total 𝑄 at cable
62
0.2 0.4 0.6 0.8 Time/s
500 1000 Offset/m
0.5 1.0 x105
Direct Receiver-ghost
E.S. cable
SLIDE 63 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Deghosted 𝑄 at E.S. (Step 1)
63
0.2 0.4 0.6 0.8 Time/s
500 1000 Offset/m
0.5 1.0 x105
Direct Receiver-ghost
E.S. cable
SLIDE 64 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Input total 𝑄 at cable
64
0.2 0.4 0.6 0.8 Time/s
500 1000 Offset/m
0.5 1.0 x105
Primary
E.S. cable
SLIDE 65 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
0.2 0.4 0.6 0.8 Time/s
500 1000 Offset/m
0.5 1.0 x105
Primary
Deghosted 𝑄 at E.S. (Step 1)
65 E.S. cable
SLIDE 66 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Deghosted 𝑄 at cable (Step 2)
66
0.2 0.4 0.6 0.8 Time/s
500 1000 Offset/m
0.5 1.0 x105
Primary
E.S. cable
SLIDE 67 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Input total 𝑄 on cable
67
0.2 0.4 0.6 0.8 Time/s
500 1000 Offset/m
0.5 1.0 x105
Primary Direct Receiver-ghost
E.S. cable
SLIDE 68 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Deghosted 𝑄 at cable (Step 2)
68
0.2 0.4 0.6 0.8 Time/s
500 1000 Offset/m
0.5 1.0 x105
Primary
E.S. cable
SLIDE 69 üDeghosting on a depth variable cable Removal of ground roll & ghost onshore Deghosting ocean bottom data
Summary
69
vProvide a two-step new method to deghost actual data
without limitation
Current deghosting method
- utput deghosted data above cable
Step 1
One-way wave prediction
- utput deghosted data on cable
Step 2
SLIDE 70
Progress
vDeghosting data on a depth variable cable vWave separation onshore for the removal of ground roll and ghosts vDeghosting data at the ocean bottom
70
SLIDE 71 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data 71
Ground roll (Rayleigh wave)
(Boustani et al., Journal of Geophysics and Engineering, 2013)
SLIDE 72
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Deliverable (J. Wu & A. Weglein, SEG 2016)
72
v A new and simplified Green’s theorem wave separation algorithm
ü for onshore ground roll and ghost removal ü with a reduced data requirement ü retains effectiveness of original algorithm (J. Wu & A. Weglein, SEG 2015)
SLIDE 73
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Marine -- Wave separation
73
Earth Air Water 𝑄&: Reference wave
𝑄& = @ 𝑄𝜖K𝐻&
' − 𝐻& '𝜖K𝑄 𝑒𝑇′ A.C.
(Weglein & Secrest 1990)
SLIDE 74
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Marine -- Data requirement
74
𝑄& = @ 𝑄𝜖K𝐻&
' − 𝐻& '𝜖K𝑄 𝑒𝑇′ A.C.
(Weglein & Secrest 1990)
Earth Air Water 𝑄&: Reference wave
SLIDE 75 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Marine -- Data requirement
75
- 𝜖K𝑄 was rarely measured in 1990s
𝑄& = @ 𝑄𝜖K𝐻&
' − 𝐻& '𝜖K𝑄 𝑒𝑇′ A.C.
(Weglein & Secrest 1990)
SLIDE 76 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Marine -- Reduce data requirement
76
- 𝜖K𝑄 was rarely measured in 1990s
- Reduce requirement of 𝜖K𝑄 with 𝐻&
' = 0 along the cable
(Osen et al. 1998, Tan 1999)
𝑄& = @ 𝑄𝜖K𝐻&
' − 𝐻& '𝜖K𝑄 𝑒𝑇′ A.C.
(Weglein & Secrest 1990)
SLIDE 77
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Onshore -- Wave separation
77
𝑣>? Reflection without ground roll & receiver ghost 𝑯& Green’s tensor in homogenous whole-space elastic reference 𝜯& Stress tensor of Green’s function 𝑣 Displacement 𝑢 ⃑ Traction
𝑣>? = @ 𝑣 6 𝑜 8 6 𝜯& − 𝑢 ⃑ 6 𝑯& 𝑒𝑇′
A.C.
(Weglein & Secrest 1990, J. Wu & Weglein, SEG, 2015)
SLIDE 78
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Onshore -- Wave separation
78
𝑣>? Reflection without ground roll & receiver ghost 𝑯& Green’s tensor in homogenous whole-space elastic reference 𝜯& Stress tensor of Green’s function 𝑣 Displacement 𝑢 ⃑ Traction
𝑣>? = @ 𝑣 6 𝑜 8 6 𝜯& − 𝑢 ⃑ 6 𝑯& 𝑒𝑇′
A.C.
(Weglein & Secrest 1990, J. Wu & Weglein, SEG, 2015) @ 𝑄𝛼′𝐻&
' − 𝐻& '𝛼′𝑄 6 𝑜
8𝑒𝑇′
A.C.
SLIDE 79
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Onshore -- Wave separation
79
Not a filtering method of ground roll removal, but a wave theory based wave prediction and no damage on 𝑣>?
𝑣>? = @ 𝑣 6 𝑜 8 6 𝜯& − 𝑢 ⃑ 6 𝑯& 𝑒𝑇′
A.C.
(Weglein & Secrest 1990, J. Wu & Weglein, SEG, 2015)
SLIDE 80
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Onshore -- Wave separation
80
𝑣>? Reflection without ground roll & receiver ghost 𝑯& Green’s tensor in homogenous whole-space elastic reference 𝜯& Stress tensor of Green’s function 𝑣 Displacement 𝑢 ⃑ Traction
𝑣>? = @ 𝑣 6 𝑜 8 6 𝜯& − 𝑢 ⃑ 6 𝑯& 𝑒𝑇′
A.C.
(Weglein & Secrest 1990, J. Wu & Weglein, SEG, 2015)
SLIDE 81
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Onshore -- Data requirement
81
𝑣>? Reflection without ground roll & receiver ghost 𝑯& Green’s tensor in homogenous whole-space elastic reference 𝜯& Stress tensor of Green’s function 𝑣 Displacement 𝑢 ⃑ Traction
𝑣>? = @ 𝑣 6 𝑜 8 6 𝜯& − 𝑢 ⃑ 6 𝑯& 𝑒𝑇′
A.C.
(Weglein & Secrest 1990, J. Wu & Weglein, SEG, 2015)
SLIDE 82
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
𝑣>? Reflection without ground roll & receiver ghost 𝑯& Green’s tensor in homogenous whole-space elastic reference 𝜯& Stress tensor of Green’s function 𝑣 Displacement 𝑢 ⃑ Traction
Onshore -- Data requirement
82
𝑣>? = @ 𝑣 6 𝑜 8 6 𝜯& − 𝑢 ⃑ 6 𝑯& 𝑒𝑇′
A.C.
(Weglein & Secrest 1990, J. Wu & Weglein, SEG, 2015) 𝑢 ⃑ = 𝜇𝜄 + 2𝜈𝜖U𝑣U 𝜈(𝜖U𝑣W + 𝜖W𝑣U) 𝜈(𝜖U𝑣E + 𝜖E𝑣U) 𝜈(𝜖U𝑣W + 𝜖W𝑣U) 𝜇𝜄 + 2𝜈𝜖W𝑣W 𝜈(𝜖W𝑣E + 𝜖E𝑣W) 𝜈(𝜖U𝑣E + 𝜖E𝑣U) 𝜈(𝜖W𝑣E + 𝜖E𝑣W) 𝜇𝜄 + 2𝜈𝜖E𝑣E 𝑜U 𝑜W 𝑜E 𝜄=𝜖U𝑣U + 𝜖W𝑣W + 𝜖E𝑣E
SLIDE 83 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data 83
The data requirement is satisfied (J. Wu and A. Weglein, SEG 2015)
⃑
SLIDE 84
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Model -- Generate data (𝒗 & 𝒖 ⃑) from air/earth
84
Layer P Velocity (m/s) S Velocity (m/s) Density (kg/m3)
1(Air) 340 3 2(Top earth) 1800 1200 1500 3(Bottom earth) 4000 2500 1800
400m
Earth (𝑣U, 𝑣E), (𝑢U, 𝑢E) Air
A/E boundary M.S. 100m
SLIDE 85 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Total 𝑣U input to the separation algorithm
85
0.5 1.0 1.5 2.0 Time/s
1000 2000 3000 Offset/m
1 2 3 4 5 x10-12
SLIDE 86 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Total 𝑣U input to the separation algorithm
86
0.5 1.0 1.5 2.0 Time/s
1000 2000 3000 Offset/m
1 2 3 4 5 x10-12
Direct Direct
SLIDE 87 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Total 𝑣U input to the separation algorithm
87
0.5 1.0 1.5 2.0 Time/s
1000 2000 3000 Offset/m
1 2 3 4 5 x10-12
Rayleigh Rayleigh
SLIDE 88 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Total 𝑣U input to the separation algorithm
88
0.5 1.0 1.5 2.0 Time/s
1000 2000 3000 Offset/m
1 2 3 4 5 x10-12
Primary Primary
SLIDE 89 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Total 𝑣U input to the separation algorithm
89
0.5 1.0 1.5 2.0 Time/s
1000 2000 3000 Offset/m
1 2 3 4 5 x10-12
Ghost Ghost
SLIDE 90 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Total 𝑣U input to the separation algorithm
90
0.5 1.0 1.5 2.0 Time/s
1000 2000 3000 Offset/m
1 2 3 4 5 x10-12
Primary Rayleigh Direct Ghost
SLIDE 91 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
0.5 1.0 1.5 2.0 Time/s
1000 2000 3000 Offset/m
1 2 3 4 5 x10-12
Deghosted 𝑣U from the separation algorithm
91
Primary
SLIDE 92 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data 92
The data requirement is satisfied (J. Wu and A. Weglein, SEG 2015)
⃑
- Effectively separate ground roll and ghosts out, without damaging reflection data
SLIDE 93 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data 93
The data requirement is satisfied (J. Wu and A. Weglein, SEG 2015)
⃑
- Effectively separate ground roll and ghosts out, without damaging reflection data
The data requirement is not satisfied (J. Wu and A. Weglein, SEG 2016)
- Measure only 𝒗, but not 𝒖
⃑
SLIDE 94
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
2D onshore experiment
94
Air Earth (𝐺
U, 𝐺 E)
A/E boundary
(𝑣U, 𝑣E)
SLIDE 95
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
2D onshore experiment -- approximation
95
Vacuum Earth (𝐺
U, 𝐺 E)
V/E boundary
(𝑣U, 𝑣E)
ü Vacuum/earth boundary
SLIDE 96
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
2D onshore experiment -- approximation
96
ü Vacuum/earth boundary ü A localized force on surface 𝐺 ⃑(𝑢)𝜀(𝑦 − 𝑦C), 𝐺 ⃑ 𝑢 : source wavelet
Vacuum Earth (𝐺
U, 𝐺 E)
V/E boundary
(𝑣U, 𝑣E)
SLIDE 97
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Boundary condition
97
𝑢 ⃑ 𝑦, 𝑨 = 0, 𝜕 = −𝐺 ⃑ 𝜕 𝜀 𝑦 − 𝑦C
𝐺 ⃑(𝜕): source wavelet Vacuum Earth (𝐺
U, 𝐺 E)
V/E boundary
(𝑣U, 𝑣E)
SLIDE 98
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Formula simplification
98
𝑣>?(𝑠 ⃑, 𝑠
C, 𝜕) = @
𝑣 6 𝑜 8 6 𝜯& − 𝑢 ⃑(𝑠 ⃑′, 𝑠
C, 𝜕) 6 𝑯&(𝑠
⃑′, 𝑠 ⃑, 𝜕) 𝑒𝑇′
A.C.
Original
𝑢 ⃑ 𝑦, 𝑨 = 0, 𝜕 = −𝐺 ⃑ 𝜕 𝜀 𝑦 − 𝑦C
𝐺 ⃑(𝜕): source wavelet
SLIDE 99
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Formula simplification
99
𝑣>?(𝑠 ⃑, 𝑠
C, 𝜕) = @
𝑣 6 𝑜 8 6 𝜯& − 𝑢 ⃑(𝑠 ⃑′, 𝑠
C, 𝜕) 6 𝑯&(𝑠
⃑′, 𝑠 ⃑, 𝜕) 𝑒𝑇′
A.C.
Original
𝑣>?(𝑠 ⃑, 𝑠
C, 𝜕) = @
𝑣 6 𝑜 8 6 𝜯& 𝑒𝑇^
A.C.
+ 𝐺 ⃑(𝜕) 6 𝑯𝟏(𝑠
C, 𝑠
⃑, 𝜕)
Simplified
𝑢 ⃑ 𝑦, 𝑨 = 0, 𝜕 = −𝐺 ⃑ 𝜕 𝜀 𝑦 − 𝑦C
𝐺 ⃑(𝜕): source wavelet
SLIDE 100
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Formula simplification
100
𝑣>?(𝑠 ⃑, 𝑠
C, 𝜕) = @
𝑣 6 𝑜 8 6 𝜯& − 𝑢 ⃑(𝑠 ⃑′, 𝑠
C, 𝜕) 6 𝑯&(𝑠
⃑′, 𝑠 ⃑, 𝜕) 𝑒𝑇′
A.C.
Original
𝑣>?(𝑠 ⃑, 𝑠
C, 𝜕) = @
𝑣 6 𝑜 8 6 𝜯& 𝑒𝑇^
A.C.
+ 𝐺 ⃑(𝜕) 6 𝑯𝟏(𝑠
C, 𝑠
⃑, 𝜕)
Simplified
Require traction everywhere along acquisition surface Require source wavelet 𝑢 ⃑ 𝑦, 𝑨 = 0, 𝜕 = −𝐺 ⃑ 𝜕 𝜀 𝑦 − 𝑦C
𝐺 ⃑(𝜕): source wavelet
SLIDE 101
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data 101
Q: Is vacuum/earth approximation useful?
SLIDE 102
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data 102
Q: Is vacuum/earth approximation useful?
ü Generate data from air/earth ü Apply simplified wave separation formula (𝑣 + 𝐺 ⃑) ü Process as though it was in vacuum/earth
SLIDE 103
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data 103
Q: Is vacuum/earth approximation useful?
ü Generate data from air/earth ü Apply simplified wave separation formula (𝑣 + 𝐺 ⃑) ü Process as though it was in vacuum/earth
SLIDE 104
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Model -- Generate data (only 𝒗) from air/earth
104
Layer P Velocity (m/s) S Velocity (m/s) Density (kg/m3)
1(Air) 340 3 2(Top earth) 700 400 600 3(Bottom earth) 1500 800 1000
200m
Earth (𝑣U, 𝑣E) (0, 𝐺
E(𝑢))
Air
A/E boundary
SLIDE 105 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Total 𝑣E input to simplified formula assuming v/e
105
0.5 1.0 1.5 2.0 Time/s
1000 Offset/m
0.5 1.0 x10-10
v/e: vacuum/earth
SLIDE 106 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Total 𝑣E input to simplified formula assuming v/e
106
0.5 1.0 1.5 2.0 Time/s
1000 Offset/m
0.5 1.0 x10-10
Rayleigh
SLIDE 107 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Total 𝑣E input to simplified formula assuming v/e
107
0.5 1.0 1.5 2.0 Time/s
1000 Offset/m
0.5 1.0 x10-10
𝑄 ` 𝑄 a + Ghost 𝑄 ` 𝑇 a/𝑇 `𝑄 a + Ghost 𝑇 `𝑇 a + Ghost
SLIDE 108 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Predicted primary from simplified formula assuming v/e
108
0.5 1.0 1.5 2.0 Time/s
1000 Offset/m
0.5 1.0 x10-10
SLIDE 109 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Total 𝑣E input to simplified formula assuming v/e
109
0.5 1.0 1.5 2.0 Time/s
1000 Offset/m
0.5 1.0 x10-10
Rayleigh
SLIDE 110 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Predicted primary from simplified formula assuming v/e
110
0.5 1.0 1.5 2.0 Time/s
1000 Offset/m
0.5 1.0 x10-10
Rayleigh
SLIDE 111 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Total 𝑣E input to simplified formula assuming v/e
111
0.5 1.0 1.5 2.0 Time/s
1000 Offset/m
0.5 1.0 x10-10
𝑄 ` 𝑄 a + Ghost 𝑄 ` 𝑇 a/𝑇 `𝑄 a + Ghost 𝑇 `𝑇 a + Ghost
SLIDE 112 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Predicted primary from simplified formula assuming v/e
112
0.5 1.0 1.5 2.0 Time/s
1000 Offset/m
0.5 1.0 x10-10
𝑄 ` 𝑄 a + Ghost 𝑄 ` 𝑇 a/𝑇 `𝑄 a + Ghost 𝑇 `𝑇 a + Ghost
SLIDE 113 Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Analytically computed primary (ideal result)
113
0.5 1.0 1.5 2.0 Time/s
1000 Offset/m
0.5 1.0 x10-10
𝑄 ` 𝑄 a + Ghost 𝑄 ` 𝑇 a/𝑇 `𝑄 a + Ghost 𝑇 `𝑇 a + Ghost
SLIDE 114
Deghosting on a depth variable cable üRemoval of ground roll & ghost onshore Deghosting ocean bottom data
Summary
114
vAssume data requirement (displacement and traction) is satisfied üSeparate ground roll and ghosts out effectively and without damaging reflection data vAssume traction requirement is not satisfied üDerive a simplified algorithm assuming vacuum/earth üSignificantly reduce data requirement (𝑣 + source wavelet) üProduce acceptable and useful result, and practical value
SLIDE 115 Progress
vDeghosting data on a depth variable cable vWave separation onshore for the removal of ground roll and ghosts vDeghosting data at the ocean bottom
115
- Pressure and multicomponent displacement
(J. Zhang & A. Weglein 2006, J. Wu & A. Weglein, SEG 2016)
SLIDE 116 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Model
116 Layer P Velocity (m/s) S Velocity (m/s) Density (kg/m3)
1(water) 1500 1000 2(top earth) 2500 1200 2000 3(bottom earth) 4000 1400 2000
F.S.
(𝒗𝒚, 𝒗𝒜)
O.B./M.S.
Water Earth
500m 300m 20m
𝑄
SLIDE 117 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Total 𝑣E input for deghosting
117
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
SLIDE 118 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Deghosted 𝑣E
118
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
SLIDE 119 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Total 𝑣E input for deghosting
119
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
SLIDE 120 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Total 𝑣E input for deghosting
120
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
SLIDE 121 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Total 𝑣E input for deghosting
121
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
SLIDE 122 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Total 𝑣E input for deghosting
122
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
SLIDE 123 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Total 𝑣E input for deghosting
123
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
SLIDE 124 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Deghosted 𝑣E
124
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
SLIDE 125 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Total 𝑣E input for deghosting
125
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
SLIDE 126 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Total 𝑣E input for deghosting
126
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
M.S. O.B. Water Earth F.S.
SLIDE 127 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Total 𝑣E input for deghosting
127
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
M.S. O.B. Water Earth F.S.
SLIDE 128 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Total 𝑣E input for deghosting
128
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
M.S. O.B. Water Earth F.S.
SLIDE 129 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Total 𝑣E input for deghosting
129
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
M.S. O.B. Water Earth F.S.
SLIDE 130 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Total 𝑣E input for deghosting
130
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
M.S. O.B. Water Earth F.S.
SLIDE 131 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Deghosted 𝑣E
131
0.5 1.0 1.5 Time/s
1000 Offset/m
1 x10-4
SLIDE 132 Deghosting on a depth variable cable Removal of ground roll & ghost onshore üDeghosting ocean bottom data
Spectrum improvement after receiver-side deghosting
132
10 20 30 40 50 60 70 Frequency/Hz
Amplitude/DB
Total 𝑣E Up/Deghosted 𝑣E
SLIDE 133
Conclusion and future work
vAdvance Green’s theorem wave separation methods
ü Propose a method to deghost data on a depth variable cable ü Extend theory to land for removing ground roll and ghosts and
further reduce data requirement
ü Extend theory to ocean bottom for deghosting both pressure and
multi-component displacement data
v Further investigate how these separation methods work for
land/ocean-bottom with less than full component
133
SLIDE 134
134
Thank you
