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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.