Primary-Only Imaging Condition Yue Wang. Outline Objective Objective POIC Methodology POIC Methodology Synthetic Data Tests Synthetic Data Tests 5-layer.

Primary-Only Imaging Primary-Only Imaging ConditionCondition

Yue WangYue Wang

OutlineOutline• • ObjectiveObjective

• POIC MethodologyPOIC Methodology

• • Synthetic Data TestsSynthetic Data Tests 5-layer model5-layer model

salt dome model salt dome model

• Unocal Field Data TestsUnocal Field Data Tests

• • Discussion and Future WorkDiscussion and Future Work

Synthetic Shot GatherSynthetic Shot Gather

Distance (m)Distance (m)

Tim

e (s

)T

ime

(s)

00

4400 30003000

Multiples

Primary

2D Kirchhoff migration2D Kirchhoff migration

*^SourceSource

ReceiverReceiver

obsobs

obsobs = = SASA + + RARA

SASA RARA

Kirchhoff Migration ImageKirchhoff Migration Image

Artificial Multiple Image

Distance (km)Distance (km)

Dep

th (

km

)D

epth

(k

m)

00

6600 55

ProblemProblem

Standard imaging conditionStandard imaging condition

DataData( primary + multiple )( primary + multiple )

ImageImage( primary + multiple )( primary + multiple )

ObjectiveObjective

Primary-Only imaging conditionPrimary-Only imaging condition

DataData( primary + multiple )( primary + multiple )








MethodologyMethodology

DataData PrimaryPrimary MultipleMultiple

== ++First-order MultipleFirst-order Multiple

Second-order MultipleSecond-order Multiple

Third-order MultipleThird-order Multiple


Primary ---------------- MultiplePrimary ---------------- Multiple

?? What DifferencesWhat Differences

Primary ReflectionsPrimary Reflections

OffsetOffset

Dep

thD

epth

*

^

SourceSource ReceiverReceiver

AA

Multiple ReflectionsMultiple Reflections

OffsetOffset

Dep

thD

epth

*

^


AA

CC

BB


For a specific event:For a specific event:

Observed traveltime Observed traveltime obsobs

shooting angle shooting angle

incident angle incident angle

Shoot ray from sourceShoot ray from source

OffsetOffset

Dep

thD

epth

*

^


OffsetOffset

Dep

thD

epth

*

^


Shoot ray from receiverShoot ray from receiver

Find crossing pointFind crossing point

OffsetOffset

Dep

thD

epth

*

^


Cross point ACross point A

SASA RARA

Primary-Only Imaging Primary-Only Imaging Condition (POIC)Condition (POIC)

One event is primary reflectionOne event is primary reflectiononly if :only if :

obsobs = = SASA + + RARA


OffsetOffset

Dep

thD

epth

*

^


AA

SASA RARA


obsobs == SASA + + RARA

MethodologyMethodology DataData

( primary + multiple )( primary + multiple )

Standard Imaging Standard Imaging ConditionCondition

obsobs


Primary Only Imaging Primary Only Imaging ConditionCondition

obsobs , , and and








5-Layer Model5-Layer Model


Dep

th (

km

)D

epth

(k

m)

00

6600 55

*Source

GeophoneLine

Shot GatherShot Gather


Tim

e (s

)T

ime

(s)

00

4400 30003000

P1

P2

P3

P4


123

4


Dep

th (

km

)D

epth

(k

m)

00

6600 55


Artificial Multiple Image


Dep

th (

km

)D

epth

(k

m)

00

6600 55

Migration Image with POICMigration Image with POIC

123

4


Dep

th (

km

)D

epth

(k

m)

00

6600 55







Salt ModelSalt Model


Dep

th (

km

)D

epth

(k

m)

00

3.53.500 55

*Source

GeophoneLine

Shot GatherShot Gather


Tim

e (s

)T

ime

(s)

00

4400 30003000


1

2

345

6

6

A.M.I.A.M.I.


Dep

th (

km

)D

epth

(k

m)

00

3.53.500 55

A.M.I.

Migration Image with POICMigration Image with POIC

1

2

345

6

6


Dep

th (

km

)D

epth

(k

m)

00

3.53.500 55







Processed CSGProcessed CSG


Tim

e (s

)T

ime

(s)

00

44175175 31753175

M1M2

NMO Corrected CMGNMO Corrected CMG


Tim

e (s

)T

ime

(s)

00

66175175 31753175

M2

CMG after Dip FilteringCMG after Dip Filtering


Tim

e (s

)T

ime

(s)

00

66175175 31753175

M2

Seismogram in Seismogram in -p Domain-p Domain

pp

Tim

e (s

)T

ime

(s)

00

66-200-200 400400

Multiple

Primary

Muting in Muting in -p Domain-p Domain

pp

Tim

e (s

)T

ime

(s)

00

66-200-200 400400

CMG after Muting in CMG after Muting in -p -p


Tim

e (s

)T

ime

(s)

00

66175175 31753175

M2

Stack before MutingStack before MutingT

ime

(s)

Tim

e (s

)00

44

M1

CDP NumberCDP Number313313 14001400

M2

M2

Stack after MutingStack after MutingT

ime

(s)

Tim

e (s

)00

M2

M2

CDP NumberCDP Number44

313313 14001400

Kirchhoff ImageKirchhoff ImageD

epth

(m

)D

epth

(m

)00

40004000

M1M2

M2

Distance (m)Distance (m)20002000 90009000

POIC ImagePOIC ImageD

epth

(ft

)D

epth

(ft

)00

40004000

M1M2

M2

Distance (m)Distance (m)20002000 90009000

ConclusionsConclusions

• POIC Works for synthetic dataPOIC Works for synthetic data

• Encouraging results for field dataEncouraging results for field data

• POIC need more accurate velocity modelPOIC need more accurate velocity model

Future WorkFuture Work

• • Apply to other field dataApply to other field data

• • Improve velocity model estimateImprove velocity model estimate

AcknowledgementAcknowledgement

We are grateful to the 1999 sponsors We are grateful to the 1999 sponsors of the UTAM consortium for the of the UTAM consortium for the financial supportfinancial support

Migration with POICMigration with POIC

Four Steps:Four Steps:

(1) pick seismic events automatically;(1) pick seismic events automatically;

obsobs



(2) calculate incidence and shooting angles (2) calculate incidence and shooting angles andand for one event using local slant for one event using local slant stack;stack;



(3) ray tracing and find the crossing point;(3) ray tracing and find the crossing point;

SASA + + RARA

Find crossing pointFind crossing point

OffsetOffset

Dep

thD

epth

*

^


Cross point ACross point A

SASA RARA

(4) (4) obs obs = = SASA + + RARA ??

No: Discard this event;No: Discard this event; Yes: Migrate this event;Yes: Migrate this event;


Raw CSGRaw CSG


Tim

e (s

)T

ime

(s)

00

44175175 31753175

CMGCMG

Offset (m)Offset (m)

Tim

e (s

)T

ime

(s)

00

66175175 31753175

M1M2

Primary-Only Imaging Condition Yue Wang. Outline Objective Objective POIC Methodology POIC Methodology Synthetic Data Tests Synthetic Data Tests 5-layer.

Documents

image primary multiple

source receiver slide

order multiple slide

future work slide

sa ra slide

multiples primary slide

methodology primary

sa ra sa ra slide