Joint Migration of Primary and Joint Migration of Primary and

Multiple Reflections in RVSP DataMultiple Reflections in RVSP Data

Jianhua Yu, Gerard T. SchusterJianhua Yu, Gerard T. Schuster

University of UtahUniversity of Utah

3.0

2.0

1.0T

ime

(s)

SP 1255 1235 1215

Drill-bit Primary Autocorrelogram MigrationDrill-bit Primary Autocorrelogram Migration

DrillDrill HoleHole

Real ?

GhostGhost

??

OutlineOutlineMotivation

Joint Migration Method

ExamplesSynthetic dataUPRC data

Summary

OutlineOutlineMotivation

Joint Migration Method

ExamplesSynthetic dataUPRC data

Summary

Source Geophone

?

RVSP While DrillingRVSP While Drilling

Provide Look-ahead Image Below Provide Look-ahead Image Below the Drill Bitthe Drill Bit

Reduce Uncertainty in DrillingReduce Uncertainty in Drilling

Source Geophone

Bit Position?Bit Position?

Problems in RVSPWDProblems in RVSPWD

Pilot signal?

Wavelet ?

Problems with Drill-bit and Problems with Drill-bit and RVSP DataRVSP Data

No source waveletNo source wavelet

No source initiation timeNo source initiation time

Not easy to get pilot signal in Not easy to get pilot signal in deviated welldeviated well and horizontal well

Static shift errors may existStatic shift errors may exist

Difficulty for separating primary Difficulty for separating primary and ghost waves from deviated and ghost waves from deviated or horizontal wellor horizontal well

Problems with Drill-bit and Problems with Drill-bit and RVSP DataRVSP Data

Solution Solution

Autocorrelogram Migration

Why do we use autocorrelation of seismic data rather than the seismogram ???

Strengths of Autocorrelogram Migration

No need to know initial time

No limits to deviated well

Be able to reduce static errors

No need

to know source wavelet

WellWell

Drill bitDrill bit

ReceiverReceiver

Primary

Direct Wave

Ghost

What is Joint Migration What is Joint Migration

What is Joint Migration What is Joint Migration

Final migration image

Ghost migration

Primary migration

Seismic Data

Joint Migration using Primary Joint Migration using Primary and Ghost Reflectionsand Ghost Reflections

Do not need to separate Do not need to separate primary and ghost wavesprimary and ghost waves

Attenuate the interferences Attenuate the interferences in migration imagein migration image

What is Benefit from Joint What is Benefit from Joint MigrationMigration

OutlineOutlineMotivation

Joint Migration Method

ExamplesSynthetic dataUPRC data

Summary

Primary Autocorrelogram Primary Autocorrelogram

Imaging Condition:Imaging Condition:

xgsxp

x

g

s xg

sx

xgsx

sg

sgAutocorrelating Trace

Primary Autocorrelogram Primary Autocorrelogram

Imaging Condition:Imaging Condition:

xgsxp

x

g

ssg

xg

sx

xgsx sg

Primary Autocorrelogram Primary Autocorrelogram

Imaging Condition:Imaging Condition:

x

g

s

sg

sg

xg

sx

xgsxp

x

g

s xg

xx0

0

xx

xgxxsxg

00

Ghost Autocorrelogram Imaging Ghost Autocorrelogram Imaging ConditionCondition:

xgxxsx

00

sg

sg

0x Autocorrelating Trace

x

g

s xg

xx0

sg0

xx

xgxxsxg

00xgxxsx

00

sg

0x

Ghost Autocorrelogram Imaging Ghost Autocorrelogram Imaging ConditionCondition:

x

g

s xg

xx0

sg0

xx

xgxxsxg

00

0x

sg

Ghost Autocorrelogram Imaging Ghost Autocorrelogram Imaging ConditionCondition:

Principle of Joint Migration Principle of Joint Migration

Seismic data: Primary + Ghost

Ghost migrationPrimary migration

Final migration image

Product

Procedure of Joint MigrationProcedure of Joint Migration Pre-processing raw dataPre-processing raw data

ggggdd )(

ggrrd

Autocorrelating seismic tracesAutocorrelating seismic traces::

Migrating traces using both primary Migrating traces using both primary MpMp and ghost imaging conditions and ghost imaging conditions Mg

Weighting primary imageWeighting primary image

Calculating weight by w= Calculating weight by w= MpMp**MgMg

OutlineOutlineMotivation

Joint Migration Method

ExamplesSynthetic dataUPRC data

Summary

OutlineOutlineMotivation

Joint Migration Method

ExamplesSynthetic dataUPRC data

Summary

Horizontal Well ModelHorizontal Well Model

0

Dep

th (

m)

3

40X (m)

V1

V2

V4

V3

V5

V6

Shot GatherShot Gather

1 2000

4

Tim

e (s

)

CSG 10

1 2000

4

Tim

e (s

)

TracesTraces

AutocorrelogramAutocorrelogram

1.6 2.10

2.5

Dep

th (

km

)

X (km)1.6 2.1

X (km)

Standard migration Joint migration

Standard Migration with Joint Migration Standard Migration with Joint Migration ((3 CSGs3 CSGs))

SourceSource

1.6 2.10

2.0

Tim

e (s

)

X (km)1.6 2.1

X (km)

With only primary Joint auto. migration

Time Migration Results (Time Migration Results (39 CSGs39 CSGs))

SourceSource

X (km)

1.6 2.10

2.5

Dep

th (

km

)

X (km)1.6 2.1

X (km)

Kirchhoff mig Auto. mig

Depth Migration With Static ErrorsDepth Migration With Static Errors

SourceSource

3 CSGs

1.6 2.10

2.5

Dep

th (

km

)

X (km)1.6 2.1

X (km)

Joint Kirchhoff mig Joint auto. mig

Depth Migration With Static ErrorsDepth Migration With Static Errors

SourceSource

39 CSGs

OutlineOutlineMotivation

Joint Migration Method

ExamplesSynthetic dataUPRC data

Summary

Acquisition SurveyAcquisition Survey

00

00 4.54.5

-5-5

East (kft)East (kft)

North

(kft)

North

(kft)

Well Rig 3C Receivers

Drill bit

10

Dep

th (

kft

)D

epth

(k

ft)

0

Recording Length: 20 sRecording Length: 20 s

Sample Interval: 2 msSample Interval: 2 ms

00

00 4.54.5

-5-5

East (kft)East (kft)

North

(kft)

North

(kft)

Well Rig

10

Dep

th (

kft

)D

epth

(k

ft)

0

9188 ft

Offset=1135-4740 ft

Main Acquisition ParametersMain Acquisition Parameters

Main Processing StepsMain Processing Steps Trace editing and static shiftTrace editing and static shift

Frequency panel analysis and noise eliminationFrequency panel analysis and noise elimination

Velocity analysisVelocity analysis

Amplitude balance and energy normalizationAmplitude balance and energy normalization

Autocorrelograms, vertical stackingAutocorrelograms, vertical stacking

Joint migrating autocorelogramsutocorelograms

Autocorrelograms of CSG 96 Autocorrelograms of CSG 96

1 100

4

Tim

e (s

)

1 10 1 10

8 s 12 s 16 s

1 0.0

3.3

Tim

e (s

)T

ime

(s)

50

Joint Migration ImagesJoint Migration ImagesTracesTraces

Acquisition Survey MapAcquisition Survey Map

Well Rig

3C Receivers

Drill bit

00

00 15001500 30003000 45004500-5000-5000

East (ft)East (ft)

Nor

th (

ft)

Nor

th (

ft)

Line ACC4

3.0

2.0

1.0T

ime

(s)

SP 1255 1235 1215

DrillDrill holehole

Joint Migration ( insert) and CDP SectionJoint Migration ( insert) and CDP Section

3.0

2.0

1.0T

ime

(s)

SP 1255 1235 1215

Primary Migration ( insert) and CDP SectionPrimary Migration ( insert) and CDP Section

DrillDrill holehole

3.0

2.0

1.0T

ime

(s)

SP 1255 1235 1215

DrillingDrilling holehole

Joint Migration ( insert) and CDP SectionJoint Migration ( insert) and CDP Section

Joint

3.0

2.0

1.0T

ime

(s)

SP 1255 1235 1215

Primary Migration ( insert) and CDP SectionPrimary Migration ( insert) and CDP Section

DrillingDrilling holehole

Primary

OutlineOutlineMotivation

Joint Migration Method

ExamplesSynthetic dataUPRC data

Summary

SUMMARYSUMMARY

Need separating primary and multiple?Need separating primary and multiple? NO

Work for deviated or horizontal well ?Work for deviated or horizontal well ? YES

Reduce the influence of static errors ?Reduce the influence of static errors ? YES

Need pilot signal ?Need pilot signal ? NO

Need source wavelet and initial time ?Need source wavelet and initial time ? NO

Suppress coherent noise ?Suppress coherent noise ? YES

Amplitude fidelity ?Amplitude fidelity ? NO

Virtual Multiple ?Virtual Multiple ? YES

AcknowledgmentsAcknowledgments

• I greatly appreciate Union Pacific I greatly appreciate Union Pacific Resources Corporation for providing Resources Corporation for providing this datathis data

• I thank the sponsors of the UTAM I thank the sponsors of the UTAM consortium for financial supportconsortium for financial support