1.5 -1.5 6.0-6.0 2100 depth (m) time (s) raw seismograms 0 2100 four-layer sand channel model 0 0...

1.51.5

-1.5-1.5

6.06.0

-6.0-6.0

21002100

Dep

th (

m)

Dep

th (

m)

Tim

e (s

)T

ime

(s)

Raw SeismogramsRaw Seismograms

0 21000 2100

Four-Layer Sand Channel ModelFour-Layer Sand Channel Model

00

00

0.80.8

Midpoint (m)Midpoint (m)

Interferometric Seismic Interferometric Seismic ImagingImaging

Jianhua Yu & Gerard T. SchusterJianhua Yu & Gerard T. Schuster

University of UtahUniversity of Utah

OutlineOutline

Passive data for IVSP while DrillingPassive data for IVSP while DrillingImaging of Free Surface CDP MultiplesImaging of Free Surface CDP Multiples

• Interferometric Principle: Interferometric Principle:

Time Diff. between Arrivals Structure Diff.Time Diff. between Arrivals Structure Diff.

• Interferometric Imaging Applications: Interferometric Imaging Applications:

Claerbout,Claerbout,Katz, 70’sKatz, 70’sxxxx

Earthquake 1900’sEarthquake 1900’s

xxxxUtah+LLNL 1997Utah+LLNL 1997

MigrateMigrate

Claerbout,Claerbout,Rickett 1999Rickett 1999xxyy

xxyyMigrateMigrate

Arbitrary Unknown Src V(z) V(x,y,z) Arbitrary Unknown Src V(z) V(x,y,z) W(t) LocationW(t) Location

NONO YESYES YESYES YESYES

NONO

YESYES YESYES YESYES

YES/YES/NONO YESYES NO?NO?

NONO YESYES YESYES

YES/YES/NONO YESYESNONO

YESYES

YESYES

YESYES

SELECTIVE HISTORY PASSIVE IMAGINGSELECTIVE HISTORY PASSIVE IMAGING

ValidityValidity

Interference PatternInterference Pattern

Optical LensOptical Lens

LASERLASER

Optical LensOptical LensOptical LensOptical Lens

t

Interference PatternInterference Pattern

Optical LensOptical Lenss s

tLASERLASERLens Deformation Time DifferencesLens Deformation Time Differences

OutlineOutline

Passive data for IVSP while DrillingPassive data for IVSP while Drilling

• Interferometric Principle: Interferometric Principle:

Time Diff. between Arrivals Structure Diff.Time Diff. between Arrivals Structure Diff.

• Interferometric Imaging Applications: Interferometric Imaging Applications:

Seismic Ghost ReflectionSeismic Ghost Reflection

DirectDirect

GhostGhost

??Find R(x,z) but not know source locationFind R(x,z) but not know source location

DirectDirect

GhostGhost

1 2DirectDirect xx

DirectDirectxx

MasterMasterSeismic Ghost ReflectionSeismic Ghost ReflectionSeismic Interferogram: Correlate TracesSeismic Interferogram: Correlate Traces

t}

MM

m(x) = (g, t + t )m(x) = (g, t + t )

gxgx gg MMxxgxgxMM

Kirchhoff Migrate psuedo-shot gathersKirchhoff Migrate psuedo-shot gathers

GhostGhost Direct Direct has kinematics of primary reflectionhas kinematics of primary reflectionxx

MM

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

Cross- or Auto-correlogram Cross- or Auto-correlogram MigrationMigration

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

Reduce Static errors influence

No need

to know source wavelet

Weakness of Correlogram Migration

Virtual Multiples & Loss of Resolution

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

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

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

Recording Length: 20 sRecording Length: 20 s

Sample Interval: 2 msSample Interval: 2 ms

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

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

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

6.06.0

-6.0-6.0

Thanks to 1997-2002 UTAM sponsors Thanks to 1997-2002 UTAM sponsors and DOE.and DOE.

Thanks to Lew Katz and Fred Followill.Thanks to Lew Katz and Fred Followill.

PrimaryPrimaryGhostGhost

1 2

Free-Surface MultipleFree-Surface Multiple

PrimaryPrimaryGhostGhost

1 2

xxPrimaryPrimary

xx PrimaryPrimary

Seismic Interferogram: Correlate TracesSeismic Interferogram: Correlate Traces

Caution: Caution: GhostGhost xx Primary = RPrimary = R3

t}

m(x) = (g, t + t )m(x) = (g, t + t )

gxgx gg MMxxgxgxMM

Kirchhoff Migrate psuedo-shot gathersKirchhoff Migrate psuedo-shot gathers

GhostGhost Primary Primary has kinematics of primary ref.has kinematics of primary ref.xx

Nine-Layered Model (J. Sheng)Nine-Layered Model (J. Sheng)

00

0.60.6

1.21.2

1.81.8

3.03.0

Dep

th (

km

)D

epth

(k

m)

2.42.4

ModelModel Crosscorrelogram imageCrosscorrelogram image

Distance (km)Distance (km)0 3.0 Distance (km)Distance (km)0 3.0

artifactsartifacts

Kirchhoff ImageKirchhoff Image

Nine-Layered ModelNine-Layered ModelKirchhoff ImageKirchhoff Image

Product ImageProduct Image=Kirch*correl.=Kirch*correl.

00

0.60.6

1.21.2

1.81.8

3.03.0

Dep

th (

km

)D

epth

(k

m)

2.42.4

Distance (km)Distance (km)0 3.0 Distance (km)Distance (km)0 3.0

artifactsartifacts

SEG/EAGE Salt ModelSEG/EAGE Salt Model00

0.60.6

1.21.2

1.81.8

2.42.4

Dep

th (

km

)D

epth

(k

m)

3.03.0

3.63.6

0 5.0 10.0 15.00 5.0 10.0 15.0Distance (km)Distance (km)

Crosscorrelogram ImageCrosscorrelogram Image00

0.60.6

1.21.2

1.81.8

2.42.4

Dep

th (

km

)D

epth

(k

m)

3.03.0

3.63.6

0 5.0 10.0 15.00 5.0 10.0 15.0Distance (km)Distance (km)

Kirchhoff ImageKirchhoff Image00

0.60.6

1.21.2

1.81.8

2.42.4

Dep

th (

km

)D

epth

(k

m)

3.03.0

3.63.6

0 5.0 10.0 15.00 5.0 10.0 15.0Distance (km)Distance (km)

Product ImageProduct Image00

0.60.6

1.21.2

1.81.8

2.42.4

Dep

th (

km

)D

epth

(k

m)

3.03.0

3.63.6

0 5.0 10.0 15.00 5.0 10.0 15.0Distance (km)Distance (km)