Autocorrelogram Migration Autocorrelogram Migration for Field Data Generated for Field Data Generated by A Horizontal Drill-bit by A Horizontal Drill-bit

SourceSource

Jianhua Yu, Lew KatzJianhua Yu, Lew Katz

Fred Followill and Gerard T. SchusterFred Followill and Gerard T. Schuster

OutlineOutline• Motivation and ObjectiveMotivation and Objective• Autocorrelogram MigrationAutocorrelogram Migration• ExamplesExamples• SummarySummary

OutlineOutline

Motivation and ObjectiveMotivation and Objective• Autocorrelogram MigrationAutocorrelogram Migration• ExamplesExamples• SummarySummary

IVSPWD ObjectiveIVSPWD Objective• Provide Look-ahead Image Below Drill Bit Provide Look-ahead Image Below Drill Bit

• Reduce Uncertainty in DrillingReduce Uncertainty in Drilling

?

ProblemsProblems• 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

Autocorrelogram MigrationAutocorrelogram Migration

No need to No need to know source know source

waveletwavelet

No limits to No limits to a deviated a deviated wellwell

No need for No need for initiation initiation time time

SolutionSolution

OutlineOutline

• Motivation and ObjectiveMotivation and Objective Autocorrelogram MigrationAutocorrelogram Migration• ExamplesExamples• SummarySummary

WellWell

Drill bitDrill bit

ReceiverReceiver

Primary wave

Primary, Ghost and Direct WavePrimary, Ghost and Direct Wave

Direct Wave

Ghost

xgsxprimary

x

g

s

Primary Autocorrelogram Primary Autocorrelogram Imaging Condition:Imaging Condition:

Primary Autocorrelogram Primary Autocorrelogram

Imaging Condition:Imaging Condition:

xgsxprimary

x

g

s

sg

g

Ghost Autocorrelogram Ghost Autocorrelogram Imaging ConditionImaging Condition:

sgxgxgsgghost

''

x

s

g’

xgxgsgghost

''

x

g

s

g’

sg

Ghost Autocorrelogram Ghost Autocorrelogram Imaging ConditionImaging Condition:

Autocorrelogram MigrationAutocorrelogram Migration

),,()(,

..

sg

gsrrm

åx

Migrated Migrated ImageImage

Autocorrelation Autocorrelation Function Function

OutlineOutline

• Motivation and ObjectiveMotivation and Objective• Autocorrelogram MigrationAutocorrelogram Migration ExamplesExamples• SummarySummary

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

Main Acquisition ParametersMain Acquisition Parameters

Drill-bit Depth: 9188 ftDrill-bit Depth: 9188 ft

Offset Range: 1135-4740 ftOffset Range: 1135-4740 ft

Recording Length: 20 sRecording Length: 20 s

Sample Interval: 2 msSample Interval: 2 ms

Station Number: 10Station Number: 10

Main Processing StepsMain Processing Steps Orienting receivers, trace editing , and static shiftOrienting receivers, trace editing , and static shift

Frequency panel analysis and noise eliminationFrequency panel analysis and noise elimination

Velocity analysis and beam steeringVelocity analysis and beam steering

Amplitude balance and energy normalizationAmplitude balance and energy normalization

Calculating autocorrelograms, vertical stackingCalculating autocorrelograms, vertical stacking

Autocorrelogram migrationAutocorrelogram migration

Raw Data Frequency Panel Raw Data Frequency Panel AnalysisAnalysis

1 100

7

Tim

e (s

)

1 100

7

Tim

e (s

)

< 5 Hz 5-15 Hz

1 100

7

Tim

e (s

)

1 100

7

Tim

e (s

)

15-25 Hz 25-40 Hz

Raw Data Frequency Panel Raw Data Frequency Panel AnalysisAnalysis

Processed CSG 96 Part of CRG 6Processed CSG 96 Part of CRG 6

1 100

7

Tim

e (s

)

1 130.5

4.5

Tim

e (s

)

Autocoreelograms Associated Autocoreelograms Associated With CRG 6With CRG 61 10

0

5

Tim

e (s

)

Primary ImagePrimary Image

1 0

4

Tim

e (s

)T

ime

(s)

50 1 50

Ghost ImageGhost Image

Autocorrlogram Migration ImagesAutocorrlogram Migration Images

TracesTraces TracesTraces

No reflections

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

1.0

3.0

2.0

1265 1235 1215

Tim

e (s

)

SP

Drilling Drilling holehole

Primary Image with CDP SectionPrimary Image with CDP Section

3.0

2.0

1.0T

ime

(s)

SP 1255 1235 1215

Ghost Image with CDP Section Ghost Image with CDP Section (Reverse Polarity)(Reverse Polarity)

DrillingDrilling holehole

OutlineOutline

• Motivation and ObjectiveMotivation and Objective• Autocorrelogram MigrationAutocorrelogram Migration• ExamplesExamples SummarySummary

SUMMARYSUMMARY

Autocorrelogram Migration works Autocorrelogram Migration works for deviated wellfor deviated well

Primary autocorrelogram image Primary autocorrelogram image correlates well with the surface-correlates well with the surface-CDP section CDP section

Ghost autocorrelogram migration Ghost autocorrelogram migration result is comparable to surface-CDP result is comparable to surface-CDP section but suffers from more noisesection but suffers from more noise

SUMMARYSUMMARY

The upgoing and downgoing The upgoing and downgoing wave separation can cause some wave separation can cause some artifacts in migration imageartifacts in migration image

AcknowledgementsAcknowledgements

• We greatly appreciate DOE for We greatly appreciate DOE for Financial support Financial support

• We are grateful to Union Pacific We are grateful to Union Pacific Resources for donating this dataResources for donating this data

• I am grateful to the 1999 sponsors of I am grateful to the 1999 sponsors of the UTAM consortium for financial the UTAM consortium for financial supportsupport