seismic interferometry: who needs a seismic source? roel snieder center for wave phenomena colorado...
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Seismic interferometry:Who needs a seismic source?
Roel SniederCenter for Wave Phenomena
Colorado School of Mines
email [email protected]://www.mines.edu/~rsnieder
download publications from:http://www.mines.edu/~rsnieder/Publications.html
Fluctuation-dissipation theorem
F
mkT
D (Einstein, 1905)
(Kubo, Rep. Prog. Phys., 29, 255-284, 1966)
Cross-correlation
)/()/()()0( cHtCcHtCHxuxu LR
t
cH / cH /
• sum of causal and acausal response• uncorrelated left- and rightgoing waves
Displacement response
m
mmmmm
m tbtau
tu
cossin)(
),(r
r
)(sin)'()(
),',( tHtuu
tGm
mm
mm
rrrr
Heaviside function
Correlation as sum over modes
ttbb
ttab
ttba
ttaa
uuC
mnmn
mnmn
mnmn
mnmn
mnBmAn
vAB
sinsin
cossin
sincos
coscos
)()()(,
)( rr
For uncorrelated modes
ttbb
ttab
ttba
ttaa
uuC
mnmn
mnmn
mnmn
mnmn
mnBmAn
vAB
sinsin
cossin
sincos
coscos
)()()(,
)( rr
nmF 2
For uncorrelated modes
ttbb
ttab
ttba
ttaa
uuC
mnmn
mnmn
mnmn
mnmn
mnBmAn
vAB
sinsin
cossin
sincos
coscos
)()()(,
)( rr
nmF 2
mcos
Correlation
m
mBmAmvAB uuFC cos)()()( 2)( rr
Green’s function
)(cos)()(),,()( HuuGm
mBmAmBAv rrrr
0 ),,()( )(2)( BAvv
AB GFC rr
Correlation
m
mBmAmvAB uuFC cos)()()( 2)( rr
Green’s function
)(cos)()(),,()( HuuGm
mBmAmBAv rrrr
0 ),,()( )(2)( BAvv
AB GFC rr
Correlation and Green’s function
),,(),,()( )()(2)( tGtGFtC BAv
BAvv
AB rrrr
- sum of causal and acausal Green’s function
- holds for arbitrary heterogeneity
Dealing with with acausal Green’s function
),,(),,()( )()(2)( tGtGFtC BAv
BAvv
AB rrrr
- truncate correlation for t<0
- average correlation for t<0 and t>0
Displacement instead of velocity
2
)(2)(
dt
CdC
dispABv
AB
t
tGtG BA
disp
BAv
),,(
),,()(
)( rrrr
),,(),,()( )()(2)(
tGtGFtdt
dCBA
dispBA
dispdispAB rrrr
Conclusion: time derivative may appear
20 30 40 50 60 70 80 90 100 110
-4500
-4000
-3500
-3000
-2500
-2000
-1500
-1000
-500
0
500
1000
1500
2000
-0.5
-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
time (microseconds)
Pulse/echo
noiseautocorrelation
(Weaver and Lobkis, Ultrasonics, 40, 435-439, 2002)
Time-reversal
When is a solution.
then is a solution as well
N.B. this does not hold in the presence of attenuation
qp ,, v
*** ,, qp v
Representation theorem
dSppdVpqqp BABABABA nvv ˆ *** ,, AAAAAA qqpp vvreplace:
dSppdVpqqp BABABABA nvv ˆ****
Left hand side
),()()()(
),()()()(
BBBB
AAAA
Gpq
Gpq
rrrrrr
rrrrrr
),(),(
),(),(
*
***
BABA
BAABBABA
rrGrrG
rrGrrGdVpqqp
reciprocity
Right hand side
),(1
)(1
)()( AAAAA Gi
pi
q rrrvrrr
dSGGGGi
dSpp
ABBA
BABA
nrrrrrrrr
nvv
ˆ),(),(),(),(1
ˆ
**
**
For spherical surface far away
rrrrr ˆ),(),( BB Gc
iG
dSGGc
dSpp BABABA ),(),(1
2ˆ *** rrrrnvv
Radiation condition:
Virtual-sources
dSGGc
GG BABABA ),(),(1
2),(),( ** rrrrrrrr
Ar
Br
r
(Wapenaar, Fokkema, and Snieder, JASA, 118, 2783-2786 2005heuristic derivation: Derode et al., JASA, 113, 2973-2976, 2003)
Field example of virtual sources
(Bakulin and Calvert, SEG expanded abstracts, 2477-2480, 2004)
reservoir
complicated overburden
Peace River 4D VSP
1 0.500.5
1x
10.5
00.51y
1 0.50
0.5
1
z
1 0.500.5
1x
10.5
00.51y
Component used,along-the-well (450)
Virtual-sources
dSGGc
GG BABABA ),(),(1
2),(),( ** rrrrrrrr
Ar
Br
r
(Wapenaar, Fokkema, and Snieder, JASA, 118, 2783-2786 2005heuristic derivation: Derode et al., JASA, 113, 2973-2976, 2003)
Excitation by uncorrelated sources on surface
)'(),'(),()()(** rrrrrr FNNc
Uncorrelated sources can be:
- sequential shots
- uncorrelated noise
Response to uncorrelated noise
)()(1
')'()',()(),(1
')',()'(),(1
),(),(1
*2
***2
*
*
BA
BA
BA
BA
ppF
dSNGdSNGF
dSdSGGc
dSGGc
rr
rrrrrr
rrrrrr
rrrr
Green’s function from uncorrelated sources
)()(2
),(),( *2
*BABABA pp
FGG rrrrrr
Ar
Br
r
(For elastic waves: Wapenaar, Phys. Rev. Lett, 93, 254301, 2004)
Response to random sources
SBASBA
SSBA ctStp rr
rrr
,
,, /),(
Ar Br
Sr
dttptpC B
T
AAB ),(),()(0
rrCorrelation:
Cross-terms
- vanish on average
- in a single realization:
freedomNTf
11
termsdiagonal
termscross
(Snieder, Phys. Rev. E, 69, 046610, 2004)
Stationary phase integration
R
ikRe
R
ikRe
i
cSnCAB
44
)()(
2
)()()(
)( *
2
RGRGi
cSnCAB
(Snieder, Phys. Rev. E, 69, 046610, 2004,for reflected waves see:
Snieder, Wapenaar, and Larner, Geophysics, in press, 2005)
Ultrasound experiment
source
receivers
54 mm
135 mm
(Malcolm et al., Phys. Rev. E, 70, 015601, 2004)
T – Deconvolved (4.5 to 15 sec)
time (sec)
dep
th (
m)
β
β
β
β
β
=100 m/s=150 m/s
=200 m/s
=250 m/s
=550 m/s
Z – Deconvolved (1 to 15 sec)
time (sec)
dep
th (
m)
ααα
α
α
=1500 m/s=1250 m/s
=1600 m/s
=1350 m/s
=2200 m/s
time (sec)
dep
th (
m)
β
β
β
β
β
=100 m/s=150 m/s
=200 m/s
=250 m/s
=550 m/s
R – Deconvolved (4.5 to 15 sec)
R – Deconvolved (1 to 4.5 sec)
time (sec)
dep
th (
m)
β
β
β
β
β
=100 m/s=150 m/s
=200 m/s
=250 m/s
=550 m/s
Seismic interferometry in Millikan Library
(Snieder and Safak, Bull. Seismol. Soc. Am., in press, 2005)
Advantage (4), use other type of data
(Shapiro et al., Science, 307, 1615-1618, 2005)
earthquake
correlation(1 year)
correlation(1 month)