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Redundant and Useless Seismic Attributes

Arthur Barnes

LandmarkLarry Fink

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Seismic Attributes Should …

• Be unique

• Have clear and useful meaning

• Subset the information

• Not be defined by resolution

• Not be overly sensitive

• Be well designed

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Duplicate Attributes are Legion

Duplicate attributes contain the same information.

They look alike and show strong correlation.

Many common amplitude, discontinuity, and other

attributes are duplicates.

You only need one attribute to measure a given

seismic property!

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Max. Abs. Amplitude Avg. Peak Amplitude Total Abs. Amplitude

Max. Peak Amplitude Max. Trough Amplitude Average Energy

Avg. Reflection Strength RMS Amplitude Amplitude Variance

Am

plit

ud

e A

ttri

bu

tes

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Reflection Strength

RM

S A

mp

litu

de

Avg

. P

ea

k A

mp

.

Reflection Strength

To

tal A

bs

. A

mp

.

Reflection Strength

RMS Amplitude

Am

pli

tud

e V

ari

an

ce

RMS Amplitude

Ave

rag

e E

ne

rgy

RMS Amplitude

To

tal A

bs. A

mp

.

Am

pli

tud

e V

ari

an

ce

Average Energy Total Abs. Amp.

Ma

x. A

bs

. A

mp

.

Max. Peak Amp.

Ma

x. T

rou

gh

Am

p.Am

plit

ud

e A

ttri

bu

tes

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Rank Correlations for 9 Amplitude Attributes

1. avg energy 4. max abs. amp 7. RMS amp

2. avg peak amp 5. max peak amp 8. total abs. amp

3. avg refl. str. 6. max trough amp 9. amp variance

1

2

3

4

5

6

7

8

9

1 2 3 4 5 6 7 8 9

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Arc LengthReflection Strength Reflection Strength

Arc

Len

gth

2 mi 2 mi

Arc Length looks like an Amplitude Attribute(Reflection Strength)

You probably don’t need arc length

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T1

T2

Driven by amplitude and frequency

Units are (???) cm/sec

Useless meaning!

Arc Length =length of wiggles

T2 – T1

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Normalized VarianceStandard Variance Standard Variance

No

rmalized

Vari

an

ce2 mi2 mi

Standard variance is an amplitude attribute

Normalized amplitude variance shows new

information, but is it useful?

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Response Attributes

Attribute values at envelope peak = wavelet property

1. Response phase

2. Response frequency

3. Response bandwidth (?)

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Synthetic Data Apparent Polarity Response Phase0

400

Tim

e (

ms)

Avoid unstable attributes

Apparent Polarity is unstable(Use Response Phase instead)

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What’s in a name?

• Reflection Strength = Inst. Amplitude = Trace Envelope

• Arc Length ~ Reflection Heterogeneity

• Response Attributes = Wavelet Attributes

• Covariance Disc. = Eigenstructure Disc. = Amoco C3

• Spectral Variance ~ Bandwidth

• Quadrature Trace = Imaginary Trace ≠ seismic attribute

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Correlation Semblance

Covariance Weighted Correlation

Discontinuity Attributes

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CorrelationC

ovariance

Covariance

Sem

bla

nce

Sem

bla

nce

Correlation

Weighted Correlation

Covariance

Weighted CorrelationC

orr

ela

tion

Weighted Correlation

Sem

bla

nce

Discontinuity Crossplots

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Discontinuity is … discontinuity!

1

2

3

4

1 2 3 4

1. Correlation

2. Covariance

3. Weighted correlation

4. Semblance

1

2

3

4

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0.0

1.5

Tim

e (s

)

2 km

0.0

1.5

Tim

e (s

)

cosine of the phase strong AGC

2 km

Cosine of the phase is the ultimate AGC

(It is more a process than an attribute)

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These contain the same information(You don’t need both)

2 km 2 km

Dip-Azimuth Combined Shaded Relief

Duplicate attributes sometimes look different

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KSOFM – time A KSOFM – time A+1

K-means – time A+1 K-means – time A+1, re-ordered

Wavefo

rm A

ttri

bu

tes

(Kohonen s

elf o

rganiz

ing featu

re m

aps &

k-m

eans c

luste

ring c

lassific

ation)

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0.0

1.5

Tim

e (s

)

7.5 km

0.0

1.5

Tim

e (s

)Instantaneous frequency

7.5 km

Response frequency

Average frequency Inst. frequency + median filter

high

low

freq

ue

nc

yResolution is a parameter of seismic attributes

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30 Hz10 Hz 70 Hz

10 Hz 30 Hz 70 Hz

Wa

ve

let T

ran

sfo

rm D

FT

(Morlet

wavele

ts)

(

Ga

bor

wave

lets

)

The difference between competing methods of SpecD is

negligible within the first 2 octaves of signal

Spectral Decomposition

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ringing spectrum

smooth spectrum

Details of attribute design can be important

Energy half-time

in boxcar window:

fuzzy image

Energy half-time in

Hamming window:

clear image

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Yoicks!

Amplitude Phase Frequency Discontinuity Miscellaneous

reflection strength instantaneous

phase

instantaneous

frequency

correlation

discontinuity

arc length

trace envelope cosine of phase weighted average

instantaneous

frequency

semblance

discontinuity

energy half-time

instantaneous

amplitude

apparent polarity weighted average

Fourier spectral

frequency

covariance

discontinuity

quadrature trace

RMS amplitude response phase response frequency eigen-structure

discontinuity

azimuth, dip

average, total

absolute amplitudes

average phase spectral bandwidth PC1 slope

maximum peak,

minimum trough

amplitudes

unwrapped phase spectral frequency

variance

PC2 dip-azimuth

(combined)

average peak,

trough amplitudes

spectral kurtosis PC3 shaded relief

average energy,

total energy

instantaneous

frequency slope

Amoco C3 Karhunen-Loeve signal

complexity

standard amplitude

variance

DFT spectral

decomposition

dip variance

normalized

amplitude variance

wavelet transform

spectral decomp.

parallelism

List of 48 attributes

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Whew!Amplitude Phase Frequency Discontinuity Miscellaneous

reflection strength response phase frequency discontinuity shaded relief

normalized

amplitude variance

bandwidth azimuth, dip

energy half-time

(amplitude change)

spectral

decomposition

parallelism

List of 12 attributes

after ruthless cleanup

More manageable and more honest

9

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Conclusions

• Too many duplicate attributes

• Too many obscure attributes

• Too many unstable attributes

• Too many poorly designed attributes

• You don’t need them!

Get rid of 39 redundant and

useless seismic attributes(Larry Fink lfink@lgc.com)

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Acknowledgements

• Landmark

• Seitel Data Ltd.

• Geological Survey of Denmark

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PC1 PC2

PC3 PC4

Principal Component Analysis of amplitude attributes

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PC1

PC

2

PC1

PC

3

PC2

PC

3

PC1 PC2 PC3

Keep PC1 and get rid of the others

Principal Component Attributes