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Imaging Conditions for Primary Reflections and for Multiple Reflections. Jianming Sheng, Hongchuan Sun, Yue Wang and Gerard T. Schuster. University of Utah. Outline. Introduction. Primary-Only Imaging Condition. Multiple-Only Imaging Condition. Conclusions. Introduction.

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imaging conditions for primary reflections and for multiple reflections
Imaging Conditions for Primary Reflections and for Multiple Reflections

Jianming Sheng, Hongchuan Sun,

Yue Wang and Gerard T. Schuster

University of Utah

outline
Outline
  • Introduction
  • Primary-Only Imaging Condition
  • Multiple-Only Imaging Condition
  • Conclusions
introduction
Introduction

Other de-multiple methods:

(prior to migration imaging)

(1) Exploit moveout differences

(2) Predict and subtract multiples

introduction4
Introduction

Our two new approaches:

(during migration imaging)

(1) POIC

(1) Primary-Only Imaging Condition:

Migrate primary reflections

Discard multiple reflections

(2) MOIC

(2) Multiple-Only Imaging Condition:

Migrate multiple reflections

Discard primary reflections

outline5
Outline
  • Introduction
  • Primary-Only Imaging Condition
  • Multiple-Only Imaging Condition
  • Conclusions
slide6

Primary-Only Imaging Condition

  • Methodology
  • Synthetic Data Example
  • Unocal Field Data Example
slide7

Forward Modeling

Primary

Multiple

S

S

R

R

Depth

Offset

Offset

slide8

M1

M1

M2

M2

M3

M3

Forward Modeled Data

Primary

Multiple

Data

P1

P1

+

Time (s)

Offset

Offset

Offset

slide9

Problem in Kirchhoff Migration

Data

( primary + multiple )

Standard imaging condition

Image

( primary + multiple )

slide10

Objective of POIC Migration

Data

( primary + multiple )

Primary-only imaging condition

Image

( primary + multiple )

slide11

Migration with POIC

Key Steps:

(1) pick seismic events automatically;

obs

slide12

Key Steps:

(2) calculate shooting angle and incidence anglefor event using local slant stack;

obs

Migration with POIC

slide13

Migration with POIC

S

R

Key Steps:

(3) Shoot ray from the source using shooting angle ;

Depth

Offset

slide14

Migration with POIC

S

R

Key Steps:

(4) Shoot ray from the receiver using incidence angle;

Depth

Offset

slide15

Migration with POIC

S

R

Key Steps:

(5) Find the crossing point P, whose traveltime is: SP +RP

Depth

P

Offset

slide16

POIC Constraint

An event is a primary reflection

only if :

obs = SP + RP

Primary reflections are migrated

calculated

picked

slide17

Multiple Reflection

S

R

Depth

P

Offset

slide18

Multiple Reflection

An event is a multiple reflection

if :

obs =SP + RP

Multiple reflections are discarded

slide19

Migration with POIC

Data

( primary + multiple )

Primary-Only Imaging Condition

obs,and

Image

( primary + multiple )

slide20

Primary-Only Imaging Condition

  • Methodology
  • Synthetic Data Example
  • Unocal Field Data Example
slide21

0

Depth (km)

6

5

0

Distance (km)

5-Layer Model

A Shot Gather

0

P1

P2

Time (s)

P3

P4

4

0

Distance (km)

3

slide22

P1

P1

P2

P2

P3

P3

P4

P4

5

5

0

0

Distance (km)

Distance (km)

Kirchhoff Image

POIC Image

0

Multiple

Depth (km)

6

slide23

Primary-Only Imaging Condition

  • Methodology
  • Synthetic Data Example
  • Unocal Field Data Example
slide24

Stack Before Multiple Removal

0

M1

Time (s)

M2

M2

4

313

1400

CDP Number

stack after p multiple removal

Stack After -p Multiple Removal

0

M1

Time (s)

M2

M2

4

313

1400

CDP Number

slide26

Kirchhoff Image

0

M1

M2

Depth (km)

M2

4

9

2

Distance (km)

slide27

POIC Image

0

M1

M2

Depth (km)

M2

4

9

2

Distance (km)

outline28
Outline
  • Introduction
  • Primary-Only Imaging Condition
  • Multiple-Only Imaging Condition
  • Conclusions
slide29

Multiple-Only Imaging Condition

  • Methodology
  • Nine-layered Model
  • SEG/EAGE Salt Model
step1 create crosscorrelograms

Ghost

G

P

Primary

Primary

S

G’

G

S

G’

G

S

G’

G

VIRTUAL

SOURCE

X

X

X

X’

X’

X’

Step1: Create crosscorrelograms
slide31

Step2: Migrate crosscorrelograms

Migration image

Trial image point

With Imaging Condition

key idea of moic

Three-layered Model

Crosscorrelogram Image

Kirchhoff Image

Reflector

Reflector

Artifacts

Artifacts

Key Idea of MOIC
key idea of moic33
Key Idea of MOIC

True

reflectors

Step3:

Multiply the

crosscorrelogram image by the Kirchhoff image

slide34

Multiple-Only Imaging Condition

  • Methodology
  • Nine-layered Model
  • SEG/EAGE Salt Model
nine layered model

0

0.6

Depth (km)

1.2

1.8

2.4

3.0

Nine-Layered Model

Model

Crosscorrelogram image

Distance (km)

Distance (km)

3.0

3.0

0

0

nine layered model36

0

0.6

Depth (km)

1.2

1.8

2.4

3.0

Nine-Layered Model

Kirchhoff Image

Product Image

artifacts

Distance (km)

Distance (km)

3.0

3.0

0

0

slide37

Multiple-Only Imaging Condition

  • Methodology
  • Nine-layered Model
  • SEG/EAGE Salt Model
seg eage salt model
SEG/EAGE Salt Model

0

0.6

1.2

Depth (km)

1.8

2.4

3.0

3.6

0 5.0 10.0 15.0

Distance (km)

crosscorrelogram image
Crosscorrelogram Image

0

0.6

1.2

Depth (km)

1.8

2.4

3.0

3.6

0 5.0 10.0 15.0

Distance (km)

kirchhoff image
Kirchhoff Image

0

0.6

1.2

Depth (km)

1.8

2.4

3.0

3.6

0 5.0 10.0 15.0

Distance (km)

product image
Product Image

0

0.6

1.2

Depth (km)

1.8

2.4

3.0

3.6

0 5.0 10.0 15.0

Distance (km)

outline42
Outline
  • Introduction
  • Primary-Only Imaging Condition
  • Multiple-Only Imaging Condition
  • Conclusions
slide43

Conclusions

POIC:

Multiples are effectively attenuated

during the imaging process

MOIC:

Multiples are considered as signal

and correctly imaged

further work
Further Work

POIC:

1) Apply to other field data sets;

2) Develop more robust algorithms;

MOIC:

1) Attenuate crosscorrelogram artifacts;

2) Deal with high-order and internal multiples.

slide45

Acknowledgments

We thank the sponsors of University of Utah Tomography and Modeling /Migration (UTAM) Consortium for their financial support . We are appreciative of

Yi Luo for his early insights into MOIC.