seeing the invisible with seismic interferometry: datuming and migration gerard t. schuster, jianhua...

Seeing the Invisible with Seismic Interferometry: Datuming and

Migration

Gerard T. Schuster, Jianhua Yu, Xiao Xiang and Jianming Sheng

University of Utah

Outline Outline

Seismic Interferometry

Interferometric Migration

Interferometric Datuming

Interferometric Tomography

Conclusions

Constructive InterferenceWave 1

Wave 2=

Destructive Interference

Wave 1

Wave 2

eiwtiwt eiwtiwt+11 22 = 2 - 2cos(w(t - t ))= 2 - 2cos(w(t - t ))2211

Interferometry uses interference patterns or time differences Interferometry uses interference patterns or time differences

=

eiwtiwt e-iwt-iwt11 22== e iw(t - t )iw(t - t )

11 22

Is the Lens Broken?Is the Lens Broken?Interference PatternInterference Pattern

Optical LensOptical LensOptical LensOptical LensOptical LensOptical Lens

tLASERLASER

LASERLASER

Buried sources redatumed to targetBuried sources redatumed to target

Interferogram only sensitive to lens geometryInterferogram only sensitive to lens geometry

Outline Outline





Conclusions

Goal: Transform Ghost Reflections into Primary Goal: Transform Ghost Reflections into Primary Reflection TraveltimesReflection Traveltimes

Uninteresting PartUninteresting Part of Mediumof Medium

Tim

eT

ime

Direct Direct

LASERLASER

DirectDirect

GhostGhost

GhostGhost

To Remove Kinematics of Traveling in UninterestingTo Remove Kinematics of Traveling in UninterestingMedium Time Shift Traces by Direct TimesMedium Time Shift Traces by Direct Times

{{MMTT

BASINBASIN



Tim

eT

ime

Direct Direct

Greens Thm: Every Point on Surface acts as a Greens Thm: Every Point on Surface acts as a Secondary SourceSecondary Source

DirectDirect

GhostGhost

GhostGhost


GhostGhost

GhostGhost



Tim

eT

ime

Direct Direct

Greens Thm: Every Point on Surface acts as a Greens Thm: Every Point on Surface acts as a Secondary SourceSecondary Source

DirectDirect GhostGhost


Source Moved to Surface. Statics EliminatedSource Moved to Surface. Statics Eliminated


Tim

eT

ime

Replace Time Shifting by CrosscorrelationReplace Time Shifting by Crosscorrelation

d(M|d(M|ss)) d(g|s)d(g|s)

MM gg

ss


Tim

eT

ime



MM gg

ss

((gg,,MM,,ss)= )= d(d(MM||ss)* )* d(g|s)d(g|s) ss

,s,s

Every VSP source at different Every VSP source at different SS reflects off M reflects off MAnd recorded at And recorded at gg


Tim

eT

ime



MM gg

ss


,s,s


We accidentally found specular ray for given (We accidentally found specular ray for given (MM,,gg),),& stationary phase says this is dominant contribution. & stationary phase says this is dominant contribution.


Tim

eT

ime



MM gg

ss


,s,s


Above Datuming Formula = CSG for source at M and Above Datuming Formula = CSG for source at M and receiver at greceiver at g

Interferometric VSP DatumingInterferometric VSP Datuming

Eliminates well statics and Eliminates well statics and uninteresting parts of the medium.uninteresting parts of the medium.

Raise Raise buried srcburied src to surface. to surface.


,s,s

Interferometric VSP DatumingInterferometric VSP Datumingby by Least SquaresLeast Squares


,s,s

d = d = EE d d zz00

Data with source at depthData with source at surface

Natural extrapolation operator

TT

[[E EE E] ] EE d dzz

T -1 TT -1 T

00d =d =

Extrapolation DeconvolutionExtrapolation DeconvolutionEDED

Interferometric Interferometric DeviatedDeviated VSP VSP DatumingDatuming

Eliminates well statics and Eliminates well statics and uninteresting parts of the medium.uninteresting parts of the medium.

Lower surface src to Lower surface src to wellwell..


,s,s

Interferometric Interferometric CDPCDP Datuming Datuming

Eliminates src/rec statics and Eliminates src/rec statics and uninteresting parts of the medium.uninteresting parts of the medium.

Lower buried src to Lower buried src to referencereference inter. inter.


,s,s

referencereflector

referencereflector

Outline Outline





Conclusions


Tim

eT

ime



MM gg

ss


,s,s

Above Formula = CSG for source at M and Above Formula = CSG for source at M and receiver at g’receiver at g’

Every surface pt at different Every surface pt at different MM acts as secondary source acts as secondary sourceTo contribute to To contribute to gg

Shot gather for source at Shot gather for source at MM and geophone at and geophone at gg


Tim

eT

ime

MM gg

ssAbove Formula = CSG for source at M and Above Formula = CSG for source at M and

receiver at g’receiver at g’Every surface pt at different Every surface pt at different MM acts as secondary source acts as secondary source

To contribute to To contribute to gg

((gg, t + t ), t + t )

MM gg MMxxggxxM,M,m(m(xx)=)=

X = trial image pt.X = trial image pt.

Outline Outline


Interferometric Migration: Exxon VSP



Conclusions

Tim

e (s

)

0.3

030 900Depth (ft)

Raw Data(CRG15)

Tim

e (s

)

0.3

030 900Depth (ft)

Ghosts

Dep

th (

ft)

1300

2000 400X (ft) 0 400X (ft)

Standard mig Xcorr. mig

Outline Outline


Interferometric Migration: CDP



Conclusions

Shots: 280Shots: 280

Shot interval: 10 mShot interval: 10 m

Receivers: 300Receivers: 300

Receiver interval: 10 mReceiver interval: 10 m

Temporal interval:1msTemporal interval:1ms

X (km)X (km)00 3300

1.81.8

De

pth

(k

m)

De

pth

(k

m)

Salt modelSalt model

X (km)X (km)00 3300

33

Tim

e (

s)T

ime

(s)

CSG 100CSG 100

X (km)X (km)00 3300

1.81.8

De

pth

(k

m)

De

pth

(k

m)

Velocity model with inaccurate salt boundary, Velocity model with inaccurate salt boundary, oceam bottom, and overburdenoceam bottom, and overburden

X (km)X (km)00 3300

1.81.8

De

pth

(k

m)

De

pth

(k

m)

Kirmig with inaccurate salt boundary, ocean Kirmig with inaccurate salt boundary, ocean bottom, and overburdenbottom, and overburden

X (km)X (km)00 3300

1.81.8

De

pth

(k

m)

De

pth

(k

m)

RT mig with inaccurate salt boundary, ocean RT mig with inaccurate salt boundary, ocean bottom, and overburdenbottom, and overburden

X (km)0 30

1.8

De

pth

(k

m)

Standard mig

Correct velocity

X (km)0 3 X (km)0 3

Standard mig

Incorrect velocity

RT mig

Summary Summary Seismic Interferometry

d(g)d(g) d(g’)d(g’)**

d(g)d(g) d(g’)d(g’)**

Summary Summary Seismic Interferometry

d(g)d(g) d(g’)d(g’)**

d(g)d(g) d(g’)d(g’)**

Time Shift = Remove UninterestingTime Shift = Remove Uninteresting Kinematics+StaticsKinematics+Statics

Datuming Datuming Migration Migration Tomography Tomography

Issues Issues 1. VSP Natural Home for Interferometry1. VSP Natural Home for Interferometry

2. CDP Interferometry2. CDP Interferometry

Eliminates statics+overburden. Widens coverageEliminates statics+overburden. Widens coverage

Effective if Effective if Guide Star/ReferenceGuide Star/Reference Interface Known Interface Known

Less Effective if Less Effective if Reference Reference not Knownnot Known

3. Interferometric Datuming3. Interferometric DatumingNaturally Datumed Data can be FilteredNaturally Datumed Data can be Filtered

ID vs EDID vs ED

Outline Outline


Interferometric Migration: CDP



Conclusions

Salt Flank Imaging PS Waves


Tim

eT

ime

Goal: Image Interface by PS Transmitted WavesGoal: Image Interface by PS Transmitted Waves

MM gg

ss

PP


PPPPPPSS

d(M|d(M|ss)) d(g|s)*d(g|s)*((gg,,MM) =) =

m(m(xx)=)=

== e e eei wi w t + t + i wi w tt -i w-i w t - t - i wi w tt

PPSS PPPP

== e ei wi w ((t t –– tt))


Tim

eT

ime


MM gg

ss

PP


PPPPPPSS

ss

d(M|d(M|ss)) d(g|s)*d(g|s)*((gg,,MM) = ) =

m(m(xx)=)=


Tim

eT

ime


MM gg

ss

PP


PPPPPPSS

ss

d(M|d(M|ss)) d(g|s)*d(g|s)*((gg,,MM) = ) =

m(m(xx)=)=

Unique Specular Point Snell’s Law OKUnique Specular Point Snell’s Law OK

g,g,MM

((gg,,MM) ) m(x) =m(x) = eei wi w ((t t –– tt))––

xx xx

xxDatuming

Migration

Interferometric Interferometric PSPS Datuming Datuming

g,g,MM

((gg,,MM) ) m(x) =m(x) = eei wi w ((t t –– tt))––

xx xx

Eliminates src/rec statics and Eliminates src/rec statics and uninteresting parts of the medium.uninteresting parts of the medium.

Raise buried src to Raise buried src to interestinginteresting inter. inter.

seeing the invisible with seismic interferometry: datuming and migration gerard t. schuster, jianhua...

Documents

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