the earth’s near surface as a vibroseis signal generator

The Earth’s Near Surface as The Earth’s Near Surface as a Vibroseis Signal Generatora Vibroseis Signal Generator

Zhiyong JiangZhiyong Jiang

University of UtahUniversity of Utah

OutlineOutline

• IntroductionIntroduction• MethodologyMethodology• Synthetic Data TestSynthetic Data Test• ConclusionsConclusions

ggss

xx

Motivation: in Indonesia gas Motivation: in Indonesia gas hydrates blur the reflectionshydrates blur the reflections

s’s’

OutlineOutline

• IntroductionIntroduction• MethodologyMethodology• Synthetic Data TestSynthetic Data Test• ConclusionsConclusions

Review: 1st-order Multiple Imaging with Review: 1st-order Multiple Imaging with Crosscorrelation MigrationCrosscorrelation Migration

directssu )|'(

ghostsgu )|(

gg

ssXX

s’s’

dxdsssusxGgsxmxgG

sgudirecrt

ghost

')|'()'|(),',()|(

)|(2

Review: 1st-order Multiple Imaging with Review: 1st-order Multiple Imaging with Crosscorrelation MigrationCrosscorrelation Migration

directssu )|'(

ghostsgu )|(

gg

ssXX

s’s’

dgdsgssxGxgG

dsdgdssgussusxGxgG

xmghostdirect

')|'()'|()|(

')|()|'()'|()|(

)(

**2

***2

dssgussugs latedirect )|()|'()|'( *

Review: Near Surface Scattering Decon.Review: Near Surface Scattering Decon.

ggss

XX

s’s’

.)|'( scattssu

1)|( FOMsgu

dxdsssusxGgsxmxgG

sguscatt

FOM

')|'()'|(),',()|(

)|(.2

1

Review: Near Surface Scattering Decon.Review: Near Surface Scattering Decon.

ggss

XX

s’s’

.)|'( scattssu

1)|( FOMsgu

dgdsgssxGxgG

dsdgdssgussusxGxgG

xmFOMscatt

')|'()'|()|(

')|()|'()'|()|(

)(

**2

1*.**2

dssgussugs FOMscatt 1*. )|()|'()|'(

gg

ss xx

s’s’

dxdsssusxGgsxmxgGsgu earlylate ')|'()'|(),',()|()|( 2

EAVEAV

earlyssu )|'(

latesgu )|(

gg

ss xx

s’s’

EAVEAV

earlyssu )|'(

latesgu )|(

dssgussugs lateearly )|()|'()|'( *

dgdsgssxGxgG

dsdgdssgussusxGxgG

xmlateearly

')|'()'|()|(

')|()|'()'|()|(

)(

**2

***2

gg

ss xx

s’s’

Why name it “EAV” (Earth as a Why name it “EAV” (Earth as a vibroseis signal generator)vibroseis signal generator)

earlyssu )|'(

latesgu )|(

Pilot signalPilot signalVibroseis traceVibroseis trace

OutlineOutline

• IntroductionIntroduction• MethodologyMethodology• Synthetic Data TestSynthetic Data Test• ConclusionsConclusions

Velocity ModelVelocity Model

6750675000 X (m)X (m)00

20002000

Dep

th (

m)

Dep

th (

m)

Shots: 676; Receivers: 50 (1100m -1600m)Shots: 676; Receivers: 50 (1100m -1600m)

Tim

e (s

)T

ime

(s)

66

00

1180m1180m 1500m1500m

CSG 333CSG 333

1180m1180m 1500m1500m

Upgoing Upgoing componentcomponent

SS

GG

XX1180m1180m 1500m1500m

Downgoing Downgoing componentcomponent

SS

GG

XX

CRG 33CRG 33

Tim

e (s

)T

ime

(s)

66

00

6750675000 X (m)X (m)

Early part Early part (pilot signal)(pilot signal)

Late part Late part (vibroseis trace)(vibroseis trace)

EAV to Upgoing ComponentEAV to Upgoing Component

6750675000 X (m)X (m)

00

20002000

Dep

th (

m)

Dep

th (

m)

ss

gg xx

g’g’

EAV to Downgoing ComponentEAV to Downgoing Component

00 X (m)X (m)

00

20002000

Dep

th (

m)

Dep

th (

m)

67506750

ss

xxgg

g’g’

Primary Migration ImagePrimary Migration Image

00

00

20002000

Dep

th (

m)

Dep

th (

m)

X (m)X (m) 67506750

ss

gg

xx

11stst-order Multiple with -order Multiple with Crosscorrelation MigrationCrosscorrelation Migration

00

00

20002000

Dep

th (

m)

Dep

th (

m)

X (m)X (m) 67506750

ss

gg

g’g’

xx

EAV to Downgoing ComponentEAV to Downgoing Component

00 X (m)X (m)

00

20002000

Dep

th (

m)

Dep

th (

m)

67506750

ss

xxgg

g’g’

OutlineOutline

• IntroductionIntroduction• MethodologyMethodology• Synthetic Data TestSynthetic Data Test• ConclusionsConclusions

ConclusionConclusion

• Free surface points can be regarded as Free surface points can be regarded as vibroseis signal generator, and direct waves, vibroseis signal generator, and direct waves, primary reflections, multiple reflections can primary reflections, multiple reflections can be regarded as the pilot signal, the response be regarded as the pilot signal, the response can be thought of as vibroseis tracecan be thought of as vibroseis trace

• With EAV, a ringy trace can be compressed With EAV, a ringy trace can be compressed into an impulsive primary reflectioninto an impulsive primary reflection

ss

xx

s’s’

gg

Pilot Pilot signalsignal

vibroseis vibroseis tracetrace

Future work: use EAV to deblur the scattering due Future work: use EAV to deblur the scattering due to gas hydrates near the sea floor to gas hydrates near the sea floor

We thank UTAM sponsors for their We thank UTAM sponsors for their financial supportfinancial support

AcknowledgmentsAcknowledgments