bedrock delineation by a seismic reflection/refraction survey at tead utah david sheley and jianhua...

Bedrock Delineation by a Bedrock Delineation by a Seismic Seismic

Reflection/Refraction Reflection/Refraction Survey at TEAD UtahSurvey at TEAD Utah

David Sheley and Jianhua YuDavid Sheley and Jianhua Yu

OutlineOutline• AcquisitionAcquisition

• Reflection ProcessingReflection Processing

• Refraction ProcessingRefraction Processing

• InterpretationInterpretation

• ConclusionsConclusions

Survey LocationSurvey LocationN

orth

Nor

th1

Mil

e1

Mil

e

Mandate:Mandate:

Image Bedrock Image Bedrock

InterfaceInterface

Bedrock Depth:Bedrock Depth:

2 – 200? m2 – 200? m

Acquisition ParametersAcquisition Parameters

• 120 40-Hz geopones120 40-Hz geopones

• 5 m receiver spacing5 m receiver spacing

• 2.5 m source spacing2.5 m source spacing

• Split spreadSplit spread

• 2630 m total line length2630 m total line length

• 1056 shot gathers1056 shot gathers

• EWG source (5 stacks)EWG source (5 stacks)

EWG SourceEWG Source

Recording ParametersRecording Parameters

• 1 ms sample interval1 ms sample interval

• 1500 samples/record1500 samples/record

• 120 active channels120 active channels

• 4-Hz low cut filter4-Hz low cut filter

• 500-Hz high cut (Nyquist) 500-Hz high cut (Nyquist) filterfilter

OutlineOutline• AcquisitionAcquisition

• Reflection ProcessingReflection Processing

• Refraction ProcessingRefraction Processing

• InterpretationInterpretation

• ConclusionsConclusions

Reflection Processing FlowReflection Processing Flow

Reformat DataReformat Data

CSG, CRG EditingCSG, CRG Editing

Band-Pass FilteringBand-Pass Filtering 10-50 Hz10-50 Hz

Automatic GainAutomatic GainControl (AGC)Control (AGC)

Reflection Processing FlowReflection Processing Flow

Reformat DataReformat Data

CSG, CRG EditingCSG, CRG Editing

Band-Pass FilteringBand-Pass Filtering 10-50 Hz10-50 Hz

Automatic GainAutomatic GainControl (AGC)Control (AGC)

Refraction andRefraction andSurface Wave MuteSurface Wave Mute

CMP 1179: Trace EditingCMP 1179: Trace Editing

Tim

e (m

s)T

ime

(ms)

00

400400

200200

800800

10001000

CMP 1179: SW and Refr. MuteCMP 1179: SW and Refr. Mute

Tim

e (m

s)T

ime

(ms)

00

400400

200200

800800

10001000

Reflection Processing FlowReflection Processing Flow

Reformat DataReformat Data

CSG, CRG EditingCSG, CRG Editing

Band-Pass FilteringBand-Pass Filtering 10-50 Hz10-50 Hz

Automatic GainAutomatic GainControl (AGC)Control (AGC)

Refraction andRefraction andSurface Wave MuteSurface Wave Mute

Velocity AnalysisVelocity Analysis

NMO CorrectionNMO Correction

Residual StaticsResidual Statics

Reflection Processing FlowReflection Processing Flow

Reformat DataReformat Data

CSG, CRG EditingCSG, CRG Editing

Band-Pass FilteringBand-Pass Filtering 10-50 Hz10-50 Hz

Automatic GainAutomatic GainControl (AGC)Control (AGC)

Refraction andRefraction andSurface Wave MuteSurface Wave Mute

Velocity AnalysisVelocity Analysis

NMO CorrectionNMO Correction

Residual StaticsResidual Statics

BP Filtering andBP Filtering andAmplitude ScalingAmplitude Scaling

F-X PredictionF-X Prediction FilteringFiltering

Trace Mixing andTrace Mixing and AGC ScalingAGC Scaling

Output ResultOutput Result

Final Reflection Section:Final Reflection Section:TimeTime

Tim

e (m

s)T

ime

(ms)

00

400400

200200

800800

00 1500150010001000500500 2500250020002000Offset (m)Offset (m)

Final Reflection Section:Final Reflection Section:DepthDepth

Dep

th (

m)

Dep

th (

m)

00

400400

200200

800800

00 1500150010001000500500 2500250020002000Offset (m)Offset (m)

CMP’s 599 and 600CMP’s 599 and 600

Tim

e (m

s)T

ime

(ms)

00

400400

200200

800800

10001000

Final Reflection Section:Final Reflection Section:TimeTime

Tim

e (m

s)T

ime

(ms)

00

400400

200200

800800

00 1500150010001000500500 2500250020002000Offset (m)Offset (m)

CMP 600CMP 600 CMP 1180CMP 1180

CMP’s 1179 and 1180CMP’s 1179 and 1180

Tim

e (m

s)T

ime

(ms)

00

400400

200200

800800

10001000

OutlineOutline• AcquisitionAcquisition

• Reflection ProcessingReflection Processing

• Refraction ProcessingRefraction Processing

• InterpretationInterpretation

• ConclusionsConclusions

117,000 First Arrival Picks117,000 First Arrival PicksT

ime

(ms)

Tim

e (m

s)

00

400400

200200

800800

10001000

Inversion ParametersInversion Parameters

• 117,000/127,000 picks117,000/127,000 picks

• 2.5 m grid size2.5 m grid size

• 2.5 m source spacing2.5 m source spacing

• 2730 x 220 m model (x,z)2730 x 220 m model (x,z)

• 160 x 80 max smoothing size160 x 80 max smoothing size

• 40 x 20 min smoothing size 40 x 20 min smoothing size

Tomographic ResidualTomographic ResidualT

rave

ltim

e R

esid

ual

(m

s)T

rave

ltim

e R

esid

ual

(m

s)4545

2525

3535

1515

5500 1515101055 IterationIteration

160 x 80160 x 80 40 x 2040 x 2080 x 4080 x 40

Velocity TomogramVelocity TomogramD

epth

(m

)D

epth

(m

)

00

200200

100100

00 1500150010001000500500 2500250020002000Offset (m)Offset (m)

00

40004000

Vel

ocit

y (m

/s)

Vel

ocit

y (m

/s)

Tomogram & Raypath DensityTomogram & Raypath DensityD

epth

(m

)D

epth

(m

)

00

200200

100100

00 1500150010001000500500 2500250020002000Offset (m)Offset (m)

Dep

th (

m)

Dep

th (

m)

00

200200

100100

00 1500150010001000500500 2500250020002000Offset (m)Offset (m)

00

40004000

Vel

ocit

y (m

/s)

Vel

ocit

y (m

/s)

00

25002500

# of

Ray

s#

of R

ays

OutlineOutline• AcquisitionAcquisition

• Reflection ProcessingReflection Processing

• Refraction ProcessingRefraction Processing

• InterpretationInterpretation

• ConclusionsConclusions

Refraction/Reflection ComparisonRefraction/Reflection ComparisonD

epth

(m

)D

epth

(m

)

00

200200

100100

00 1500150010001000500500 2500250020002000500500

3000+3000+

Vel

ocit

y (m

/s)

Vel

ocit

y (m

/s)

Offset (m)Offset (m)

Dep

th (

m)

Dep

th (

m)

00

200200

100100

00 1500150010001000500500 2500250020002000Offset (m)Offset (m)

Refraction/Reflection with WellsRefraction/Reflection with WellsD

epth

(m

)D

epth

(m

)

00

200200

100100

00 1500150010001000500500 2500250020002000500500

3000+3000+

Vel

ocit

y (m

/s)

Vel

ocit

y (m

/s)

Dep

th (

m)

Dep

th (

m)

00

200200

100100

00 1500150010001000500500 2500250020002000

Offset (m)Offset (m)

Offset (m)Offset (m)

InterpretationInterpretationD

epth

(m

)D

epth

(m

)

00

200200

100100

00 1500150010001000500500 2500250020002000500500

3000+3000+

Vel

ocit

y (m

/s)

Vel

ocit

y (m

/s)

Dep

th (

m)

Dep

th (

m)

00

200200

100100

00 1500150010001000500500 2500250020002000

Offset (m)Offset (m)

Offset (m)Offset (m)

OutlineOutline• AcquisitionAcquisition

• Reflection ProcessingReflection Processing

• Refraction ProcessingRefraction Processing

• InterpretationInterpretation

• ConclusionsConclusions

ConclusionsConclusions• Refraction tomography provides Refraction tomography provides

confidence in the reflection image. confidence in the reflection image.

• 40-Hz geophones did not sufficiently 40-Hz geophones did not sufficiently attenuate surface wave energy.attenuate surface wave energy.

• Source induced noise contaminated Source induced noise contaminated near offset traces.near offset traces.

• The source produced adequate The source produced adequate energy to image the bedrock contact.energy to image the bedrock contact.