Interferometric Extraction Interferometric Extraction ofof

SSP from Passive Seismic SSP from Passive Seismic Data Data

Yanwei XueYanwei Xue

Feb. 7, 2008Feb. 7, 2008

OUTLINEOUTLINE

MotivationMotivationTheoryTheoryField data testField data testConclusions and the way aheadConclusions and the way ahead

MotivationMotivation

No individual experiment requiredCan get Green’s function between

two randomly selected receivers

Why?Why?

How?How?

Interferometric Transform

OUTLINEOUTLINE

MotivationMotivationTheoryTheoryField data testField data testConclusions and the way aheadConclusions and the way ahead

Random Sources

<N(x)*N(x’)> =δ(x-<N(x)*N(x’)> =δ(x-x’)S(ω)x’)S(ω)

P(B) =P(B) =∫ G(B|x)N(x)d x 22

SSsrcsrc

ImIm[G(A|B)] = k<p(A)*p(B)>[G(A|B)] = k<p(A)*p(B)>

= k= k∫ G(B|x)G(A|x)*d x22

SSsrcsrc

AA BB.. ..

SS00

SSsrcsrc

xx

x’x’zz

Random Scatterers

Workflow

Input data dInput data d Truncate d in time into Truncate d in time into several data panelsseveral data panels

Crosscorrelate each Crosscorrelate each trace with a given trace trace with a given trace

at xat x

Sum and average the Sum and average the crosscorrelation panelscrosscorrelation panels

Output Output

OUTLINEOUTLINE

MotivationMotivationTheoryTheoryField data testField data testConclusion and the way aheadConclusion and the way ahead

Data Introduction

8 receiver lines

779 receivers

Receiver interval:

27 - 30 m1

2

3

4

5

6

7

8

61061000

0000 61006100X (m)X (m)

Y (

m)

Y (

m)

Receiver positionReceiver position

Am

plit

ude

Time (s)0 960

Trace ExampleTrace Example

Virtual Shot Virtual Shot GatherGather

Receiver line 6

90 receivers

Frequency used to do the interferometry is 1 - 11.5 Hz

Event velocity 1450 m/s

0.0

2.40 250

0

Tim

e (

s)

X (m)

0.0

2.40 250

0

Tim

e (

s)

X (m)

Receiver line 6

90 receivers

Frequency used: 1 – 9 Hz

Event velocity 1450 m/s

Virtual Shot Virtual Shot GatherGather

Virtual Shot Virtual Shot GatherGather

0.0

2.40 250

0

Tim

e (

s)

X (m)

Receiver line 8

95 receivers

Frequency used: 1 - 9 Hz

Event velocity 1455 m/s

0.0

2.40 250

0

Tim

e (

s)

X (m)

Virtual Shot Virtual Shot GatherGather

Receiver line 2

90 receivers

Frequency used: 1 - 5 Hz

Receiver line 2

90 receivers

Frequency used: 1 - 44 Hz

Left-going events removed

0.0

2.40 250

0

Tim

e (

s)

X (m)

Virtual Shot Virtual Shot GatherGather

OUTLINEOUTLINE

IntroductionIntroductionTheoryTheoryField data testField data testConclusions and the way aheadConclusions and the way ahead

ConclusionsConclusionsField data test gives Field data test gives

continuous eventscontinuous eventsLow frequency results have Low frequency results have a velocity of 1450 m/sa velocity of 1450 m/sHigh frequency (1 - 44 Hz) High frequency (1 - 44 Hz) results look like reflectionsresults look like reflections

We need records with longer We need records with longer time to get better resultstime to get better results

Road AheadRoad Ahead

Test the data with longer time Test the data with longer time recordsrecords

Velocity analysis of the virtual Velocity analysis of the virtual gathersgathers

Migrate the virtual dataMigrate the virtual data

Thanks!Thanks!