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[email protected]. edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected] Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

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Page 1: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Wave-equation MVA by inversion of differential

image perturbations

Paul Sava & Biondo BiondiStanford University

SEP

Page 2: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Motivation

Page 3: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Wave-equation MVA (WEMVA)

• Band-limited• Multi-pathing• Resolution

• Born approximation– small anomaly

• Rytov approximation– phase unwrapping

Page 4: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Wave-equation MVA (WEMVA)

• WE tomography– data space

• WE MVA– image space

Page 5: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Outline

1. WEMVA overview

2. Born image perturbation

3. Differential image perturbation

4. Example

Page 6: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

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A tomography problem

sqs LΔminΔTraveltime

MVA

Wave-equation tomography

Wave-equation MVA

q t traveltime

d

data

Rimage

L ray field wavefield wavefield

Page 7: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Δss0

sii 0seW U

WEMVA: main idea

0WWWΔ

0s

0s0 eW iU

Page 8: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Born approximation 1eWΔW Δs

0 i

ΔsWΔW 0 i

iei 1

ie

sR LΔ

Page 9: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

WEMVA: objective function

slowness perturbation

image perturbation

slownessperturbation(unknown)

Linear WEMVAoperator

imageperturbation

(known)

sRs LΔminΔ

Page 10: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

WEMVA: objective function

sRs LΔminΔ

Traveltime

MVA

Wave-equation tomography

Wave-equation MVA

t d R

Page 11: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Fat ray: GOM example

Page 12: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Outline

1. WEMVA overview

2. Born image perturbation

3. Differential image perturbation

4. Example

Page 13: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

“Data” estimate

Traveltime

MVA

Wave-equation tomography

Wave-equation MVA

t d Rray

tracing

data

modeling

residual

migration

sRs LΔminΔ

Page 14: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Prestack Stolt residual migration

• Background image R0

• Velocity ratio 0RSR

RR0

Page 15: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

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Prestack Stolt residual migration

0RRR • Image perturbation

RR0

Page 16: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Born approximation

Page 17: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

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Residual migration: the problem

Correct velocity Incorrect velocity

Zero offset image

Angle gathers

Zero offset image

Angle gathers

Page 18: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Born approximation

Page 19: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Outline

1. WEMVA overview

2. Born image perturbation

3. Differential image perturbation

4. Example

Page 20: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Differential image perturbation

0

1

ˆ Rd

dSR

00 RRSR Image

difference

Image differential

Computed Measured

Page 21: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Differential image perturbation

R

R

0

1

ˆ Rd

dSR

00 RRSR

R

Page 22: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Phase perturbation

Page 23: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Differential image perturbation

Page 24: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Born approximation

Page 25: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: background image

Zero offset image

Angle gathers

Background image

Page 26: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

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Example: differential image

Zero offset image

Angle gathers

Differential image

Page 27: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: slowness inversion

Slowness perturbation

Image perturbation

Page 28: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: updated image

Updated slowness

Updated image

Page 29: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: correct image

Correct slowness

Correct image

Page 30: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Outline

1. WEMVA overview

2. Born image perturbation

3. Differential image perturbation

4. Example

Page 31: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Field data example

• North Sea– Salt environment– Subset

– One non-linear iteration• Migration (background image)

• Residual migration (image perturbation)

• Slowness inversion (slowness perturbation)

• Slowness update (updated slowness)

• Re-migration (updated image)

location

dep

th

Page 32: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

location

dep

thde

pth

Page 33: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

dep

th

velocity ratio velocity ratio

Page 34: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

1

1

1

location

dep

thde

pth

Page 35: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

location

dep

th

location

Page 36: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

location

dep

th

location

Page 37: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

location

dep

thde

pth

Page 38: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

location

dep

thde

pth

Page 39: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Summary

• MVA– Wavefield extrapolation methods– Born linearization– Differential image perturbations

• Key points– Band-limited (sharp velocity contrasts)– Multi-pathing (complicated wavefields)– Resolution (frequency redundancy)

Page 41: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

MVA information (a)Traveltime MVA Wave-equation MVA

• Offset focusing (flat ADCIG) • Offset focusing (flat ADCIG)

z

z

xx

Page 42: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

MVA information (b)Traveltime MVA Wave-equation MVA

• Offset focusing (flat ADCIG) • Offset focusing (flat ADCIG)

• Spatial focusing

z

z

xx

Page 43: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

MVA information (c)Traveltime MVA Wave-equation MVA

• Offset focusing (flat ADCIG) • Offset focusing (flat ADCIG)

• Spatial focusing

• Frequency redundancy

low high

Page 44: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

low high

WEMVA cost reduction

• Full image– Offset focusing

– Spatial focusing

– Frequency

• Normal incidence image

– Spatial focusing

– “fat” rays

Page 45: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Another example

Page 46: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: correct model

Zero offset image

Angle gathers

Page 47: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: background model

Zero offset image

Angle gathers

Page 48: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: correct perturbation

Zero offset image

Angle gathers

Page 49: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: differential perturbation

Zero offset image

Angle gathers

1d

dRR

Page 50: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: perturbations comparison

Differential

Difference

Correct

Page 51: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: differential perturbation

Zero offset image

Angle gathers

Page 52: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: difference perturbation

Zero offset image

Angle gathers

Page 53: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: updated model

Zero offset image

Angle gathers

Page 54: Paul@sep.stanford.edu Wave-equation MVA by inversion of differential image perturbations Paul Sava & Biondo Biondi Stanford University SEP

[email protected]

Example: correct model

Zero offset image

Angle gathers