vsp multiple interferometry

VSP Multiple InterferometryVSP Multiple Interferometry

BBAA

xx

BBAA

xx

BBAA

xx

3x3 Classification Matrix3x3 Classification Matrix

SSPSSP VSPVSP SWPSWP

VSPVSP

SSPSSP

SWPSWP

SSPSSP SSPSSP SSPSSP SSPSSPVSPVSP SWPSWP

VSPVSP VSPVSP VSPVSP

SWPSWP SWPSWP SWPSWP

VSPVSP

SWPSWP

SWPSWP

VSPVSP

SSPSSP

SSPSSP

Interferometry SummaryInterferometry Summary

x

= G(= G(AA||BB)) G(G(AA||xx)*)* G(G(BB||xx))

BBAA

xx

BBAA

xx

BBAA

xx

kk

Key Point #2: Every Bounce Pt on Surface Acts a New Key Point #2: Every Bounce Pt on Surface Acts a New Virtual SourceVirtual Source

Key Point #1: Common Raypath CancelsKey Point #1: Common Raypath Cancels

Key Point #3: Summation over Sources Picks out Specular ContributionKey Point #3: Summation over Sources Picks out Specular Contribution

Key Point #4: Kills Source Statics and no need to know src location or excitation timeKey Point #4: Kills Source Statics and no need to know src location or excitation time

Key Point #5: Huge increase in Illumination AreaKey Point #5: Huge increase in Illumination Area

Correlation RedatumingCorrelation RedatumingVSP ->SSPVSP ->SSP

x


Standard VSP PrimaryStandard VSP Primary VSP -> SSPVSP -> SSP

kk

Theory VSP -> SSPTheory VSP -> SSP

AA

xx

Reciprocity Correlation EquationReciprocity Correlation Equation

BB

Given: VSP data G(Given: VSP data G(AA|x)|x)

Find: SSP data G(Find: SSP data G(AA||BB))

AA

xx


BB

SS oooo

SS oo

SS wellwell



AA

xx


BB

{ }{ }G(A|x)G(B|x) G(B|x) - G(A|x) d x

2= G(A|B) - G(B|A)n** ** **

S + S + SS + S + Swellwell oooooo

SS oooo

SS oo

SS wellwell



x

= Im[G(= Im[G(AA||BB)])] G(G(AA||xx)*)* G(G(BB||xx))kk




x


AA

xx

BBAA

xx

BB AA

xx

BB

G(G(A|A|xx)) G(G(BB||xx))** G(G(BB|A|A))

VSP => SSPVSP => SSP

ExamplesExamples

1. 2D Synthetic VSP Data1. 2D Synthetic VSP Data

2. 2D Field VSP Data2. 2D Field VSP Data

3. 3D VSP Data3. 3D VSP Data

Well

2

0D

epth

(k

m)

0 3X (km)

SEG/EAGE Model

256 Sources

V = 1.5 - 3.0 km/s

Well

2

0D

epth

(k

m)

0 3X (km)

Receiver interval: 10 m

Receiver depth range: 0.1 -1 km

Receiver number: 91

Sample interval: 1 ms

Recording length: 3 s

Well location: (1.5 km, 0 km)

Source interval: 10 m

Source number: 256

Acquisition Parameters:

1 km

ImplementationImplementation

x


AA

xx

BBAA

xx

BB AA

xx

BB

VSP VSP SSPVSP VSP SSP

1. FK Filter up and downgoing waves1. FK Filter up and downgoing waves

2. Correlation: 2. Correlation: (A,B,x) = (A,B,x) = G(G(AA||xx)*)* G(G(BB||xx))

3. Summation: 3. Summation: x

= Im[G(= Im[G(AA||BB)])] kk (A,B,x) (A,B,x)

4. Migration:4. Migration: M(x) = M(x) = Mig(G(Mig(G(AA|B|B))))

Tim

e (s

)

3

00.2 0.9Depth (km)

CSG 160

Tim

e (s

)

3

00.2 0.9Depth (km)

Ghosts (CSG 160)

Tim

e (s

)

3

00 2.4X (km) 1.4 2.4X (km)

Xcross 60CRG 60

2.0

0.5

Dep

th (

km

)

0.5 2.5X (km)

Kirchh Mig (45) Xcorr Mig (45) Xcorr. Mig(15’)

2.52.5 0.5 0.5

Sta

tic

erro

rs (

ms)

-50

500 900Well Depth (m)

Raw Data

Static Errors at Well

2.0

0.5

Dep

th (

km

)

0.5

Kirchhoff MigrationStatic Error: 0

X (km)

Static Error: 25 ms

2.5

Static Error: 50ms

2.52.5 0.5 0.5

2.0

0.5

Dep

th (

km

)

0.5

Crosscorrelation MigrationStatic Error: 0

X (km)

Static Error: 25ms

2.5

Static Error: 50 ms

2.52.5 0.5 0.5

Lesson: Immune to statics at wellLesson: Immune to statics at well

Velocity ModelVelocity Model

00

13001300

92592500 X (m)X (m)

Dep

th (

m)

Dep

th (

m)

19001900

40004000V (m/s)V (m/s)

Shots: 92; Receivers: 91 (50m -950 m)Shots: 92; Receivers: 91 (50m -950 m)

WellWell

CSG 51CSG 51

5050 950m950m 950m950m5050

Tim

e (s

)T

ime

(s)

33

00Ghost ComponentGhost Component

SS

GG

XX

AAWellWell

CSG 51CSG 51

5050 950m950m 950m950m5050

Tim

e (s

)T

ime

(s)

33

00Primary ComponentPrimary Component

SS

GG

XX

AAWellWell

X (m)X (m)00 925925

00

13001300

Dep

th (

m)

Dep

th (

m)

X (m)X (m) 92592500

PrimaryPrimary 1st-order multiple 1st-order multiple 8 Receivers8 Receivers

Lesson: Super-illuminationLesson: Super-illumination

ExamplesExamples


2. 2D Field VSP Data:Friendswood Data2. 2D Field VSP Data:Friendswood Data


Tim

e (s

)

0.3

030 900Depth (ft)

Raw Data(CRG15)

Tim

e (s

)

0.3

030 900Depth (ft)

Ghosts

5 24Trace No.

Tim

e (s

)

1.2

0.2 xcorr data (muted)

Tim

e (s

)

1.4

0.55 24Trace No.

Field Data (CSG 25)

Raw data (muted)

Master trace Master trace

Dep

th (

ft)

1300

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

Standard mig Xcorr. mig

Dep

th (

ft)

1100

0

Standard Well data Xcorr.

Exxon Data

ExamplesExamples


2. 2D Field VSP Data:Middle East Data2. 2D Field VSP Data:Middle East Data


A RealReal Walkaway VSP Experiment

00

0

15001500

1000010000Offset (m)Offset (m)

DepthDepth (m)(m)

wellwell

12 geophones at ~ 1400 - 1500 m depth12 geophones at ~ 1400 - 1500 m depth14001400

401 shots on a topographic surface401 shots on a topographic surface

A Common Receiver GatherA Common Receiver Gather

0.40.4

1.81.8

Time (s)Time (s)

00 1000010000Offset (m)Offset (m)

Work flowWork flow

Separate up and down going wavefieldsSeparate up and down going wavefields

Ray tracingRay tracing

Upgoing wavefieldUpgoing wavefield Downgoing wavefieldDowngoing wavefield

Pick first-breakPick first-break

Primaries migrationPrimaries migration Specular interferometrySpecular interferometry

Multiples migrationMultiples migration

StaticsStatics StaticsStaticsStaticsStatics

Standard vs Interferometry Mig VSP(Narrow vs Wide Illumination)

geophones

Tim

e (ms)

1600

100

500 m 1000 m

1500 m

VSP Interferometry Imaging

VSPPrimariesmigration

ExamplesExamples


2. 2D Field VSP Data: GOM Data2. 2D Field VSP Data: GOM Data


50005000

130001300000 5600056000X (ft)X (ft)

De

pth

(ft)D

ep

th (ft)

VSP Multiple (12 receivers 13 kft @ VSP Multiple (12 receivers 13 kft @ 30 ft spacing; 500 shots) 30 ft spacing; 500 shots)

TLE, Jiang et al., 2005TLE, Jiang et al., 2005

50005000

130001300000 5600056000X (ft)X (ft)

De

pth

(ft)D

ep

th (ft)

Surface SeismicSurface Seismic


50005000

130001300000 5600056000X (ft)X (ft)

De

pth

(ft)D

ep

th (ft)

VSP Multiple (12 receivers 13 kft @ VSP Multiple (12 receivers 13 kft @ 30 ft spacing; 500 shots) 30 ft spacing; 500 shots)


ExamplesExamples



3. 3D VSP Data: Synthetic3. 3D VSP Data: Synthetic

3D SEG Salt Model Test3D SEG Salt Model Test

(He, 2006)(He, 2006)

VSP Multiples MigrationVSP Multiples Migration

( CourtesyCourtesy of P/GSI: ~¼ million traces, ~3 GB memory, ~4 hours on a PC )

Stack of 6 receiver gathersStack of 6 receiver gathers

(He, 2006)(He, 2006)

ExamplesExamples



3. 3D VSP Data: GOM BP Data3. 3D VSP Data: GOM BP Data

Field Data Application

Survey GeometrySurvey Geometry

Each geophone groupEach geophone grouphas 12 geophones.has 12 geophones.

~ 11 km~ 11 km

~ 11 km~ 11 km

~ 5 km deep~ 5 km deep

3 similar spirals,3 similar spirals,each correspondingeach correspondingto an offset-edto an offset-edgeophone group.geophone group.

3D WEIM Result3D WEIM ResultMigration of only one receiver gatherMigration of only one receiver gather

Slice of 3D WEIM ResultSlice of 3D WEIM Result

Slice of 3D WEIM ResultSlice of 3D WEIM ResultWhy was the 2D mirror migration good out to 50,000 feet offset?Why was the 2D mirror migration good out to 50,000 feet offset?

VSP->SSP SummaryVSP->SSP Summary

x


BBAA

xx

BBAA

xx

BBAA

xx

kk

Key Point #2: Every Bounce Pt on Surface Acts a New Key Point #2: Every Bounce Pt on Surface Acts a New Virtual SourceVirtual Source

Key Point #1: Common Raypath CancelsKey Point #1: Common Raypath Cancels

Key Point #3: Summation over Sources Picks out Specular ContributionKey Point #3: Summation over Sources Picks out Specular Contribution

Key Point #4: Kills Source Statics and no need to know src location or excitation timeKey Point #4: Kills Source Statics and no need to know src location or excitation time

Key Point #5: Huge increase in Illumination AreaKey Point #5: Huge increase in Illumination Area

VSP->SSP CaveatsVSP->SSP Caveats

x


BBAA

xx

BBAA

xx

BBAA

xx

kk

1. Infinitely source wide aperture. Artifacts must be recognized/fixed)1. Infinitely source wide aperture. Artifacts must be recognized/fixed)

2. No attenuation assumed (remedy: attenuation compensation)2. No attenuation assumed (remedy: attenuation compensation)

3. Be careful beneath salt domes (extra bounces get double defocused3. Be careful beneath salt domes (extra bounces get double defocused

by salt).by salt).3. Violation of assumptions seems ok for kinematics, not amplitudes3. Violation of assumptions seems ok for kinematics, not amplitudes

Loss of some lateral resolution?

Be careful about virtual multiple

Xcorr

Narrow Angle

Kirchhoff

Wide Angle

vs

Ghost is weaker than primaryExtra summation compared to KM

VSP->SSP CaveatsVSP->SSP Caveats

2D, not 3D theory..but mirror mig. is 3D

vsp multiple interferometry

Documents