Migration Deconvolution for VSP and Surface Data
description
Transcript of Migration Deconvolution for VSP and Surface Data
Migration Deconvolution Migration Deconvolution for VSP and Surface Datafor VSP and Surface Data
Jianhua YuJianhua Yu
Feb 3, 2005Feb 3, 2005
OutlineOutlineMotivation
Migration Deconvolution
Examples
Summary
OutlineOutlineMotivation
Migration Deconvolution
Examples
Summary
5
10
Dep
th (
km
)
WE Mig.
MD
Surface Seismic Migration and MD images
3D
VSP Data: VSP Data:
Irregular acquisition geometry
well
2D
Objectives : Objectives :
Improve spatial resolution
Enhance illumination
Suppress migration noise and artifacts
Develop migration deconvolution for VSP data
OutlineOutlineMotivation
Migration Deconvolution
Examples
Summary
mMigration Modeling
Migration image
RG GT
Reflectivity
Migration:
G GT -1
][ G GT -1
][RG GT m
Migration deconvolution:
mR G GT -1
][
Migration Green’s Function
sgsoogsgomig rdrdrrGrrGrrGrrGrr
)()()()()( **
MD image
Migration Deconvolution
)(~
),,~,(~
...,),,,~,(~
),,,~,(~
)(~21 inppippippii zkRzyxzkzyxzkzyxzkzkm
FFT of ),,,,( ippj zyxzyx
MigratedMigrated
datadata
m
True True ReflectivityReflectivity
R
Discrete Migration deconvolution
OutlineOutlineMotivationMigration deconvolution
Examples
Summary
VSP data
Surface seismic data
3 km
3 km
1.75 km
Nsx=Nsy=21, dsx=dsy=150 m
12 g
eoph
one
Ng=12, dgz=50 m
(750 m – 1300m)
VSP Geometry: source 21 x 21; geophone: 12
Depth=1.75 kmMigration MD
3 km
3 km
1.75 km
Nsx=Nsy=21, dsx=dsy=150 m
30 g
eoph
one
Ng=30, dgz=50 m
(100 m – 1500m)
Depth=1.75 km
Migration MD
OutlineOutlineMotivationMigration deconvolution
Examples
Summary
VSP data from salt model
Surface seismic data
750 m
21 g
eop
hon
es
7 km
16 km
320 shots
2D
Velocity
X (km)
Dep
th (
km)
Well
X (km)
Tim
e (s
)
10
0
0 15
CRG 21 (z=7.75 km)
(Courtesy of BP)
X (km)0 15
CRG 1 (z=7.0 km)
Primary Migration Image
X (km)
Dep
th (
km)
12
5
0 15
X (km)0 10
MDX (km)
Dep
th (
km
)
10
8
0 10
MIG
X (km)4 10
MDX (km)
Dep
th (
km
)
10
8
4 10
MIG
OutlineOutlineMotivationMigration deconvolution
Examples
Summary
vsp data
Surface seismic data
L500
Mig (Unocal) MD
X XT
ime
(s)
0.0
4.5
L500
Mig (Unocal) MD
X XT
ime
(s)
1.0
4.0
X10
Mig (Unocal) MD
Y YT
ime
(s)
1.0
5.0
X10
Mig (Unocal) MD
Y YT
ime
(s)
2.5
4.0
Inline 171
1 500Xline 1 500Xline
Tim
e (s
)
2.4
4
MIG (Unocal) MD
Mig MDYcross x=50T
ime
0.5
4.50 41Y (kft) 0 41Y (kft)
Mig MDYcross x=50T
ime
0.5
2.00 41Y (kft) 0 41Y (kft)
Mig MDXcross Y=125T
ime
0.5
4.50 12X (kft) 0 12X (kft)
Mig MDT
ime
2.5
4.5
Xcross Y=125
4 12X (kft) 4 12X (kft)
Xline 181
1 170Inline 1 170Inline
Tim
e (s
)
2.4
4
MDMIG (Unocal)
Xline 281
1 170Inline 1 170Inline
Tim
e (s
)
2.4
4
MDMIG (Unocal)
Mig MD
0
Z=3.0s
12.75X(kft) 0 12.75X(kft)
Y (
kft)
41
0
1 170Inline 1 170Inline
Xli
ne
1
550
MDMIG (Unocal)
3.4 s
1 170Inline 1 170Inline
Xli
ne
1
550
MDMIG (Unocal)
3.6 s
OutlineOutlineMotivationMigration deconvolution
Examples
Summary
VSP data from salt model
Surface seismic data
MD improves the resolution of VSP and surface migrated image partly
The cost depends acquisition geometry and filter length used
Summary
Time MD and poststack MD is more stable.
Summary
To reduce computational cost:
Analytic MD operator
Decimated acquisition geometry
Mig MD
Fre
q
0
120
Spectrum for Meandering Model
Mig MD
Fre
q
0
120
Spectrum for Unocal Data
AcknowledgementsAcknowledgements
UTAM Sponsors
BP, Unocal
Brian Hornby, Hans Sugianto
X10
Mig (Unocal) MD
Y YT
ime
(s)
1.0
5.0