Overview

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Overview
Fundamentals
Introduction
Seismic waves Propagation Velocity and Amplitudes
Seismogram
Measurement systems
Sources, receivers, Acquisition strategies
Data processing
Pre-processing
Filter und Deconvolution
Velocity analysis and Stacking
Migration
Interpretation
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Basic scheme of the seismic data processing
Measurements
Loading of the data/conversion
Navigation
Demultiplexing
Pre-Processing
Geometry
Editing
Amplitude correction
Frequency filter
Deconvolution
Prestack
CMP-Sorting
Velocity analysis
NMO-Correction
Stacking
Migration
Poststack
Post-processing
Printing/storage
Printing/storage
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Frequency analysis

• Analysis of the frequency content of the data
• Difference in frequency content for interface
  waves, Noise and Reflections
• In what frequency range are the reflections
  present ?

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Outline

• Periodic and transient waveforms
• Fourier transformation time domain lt-gt frequency
  domain
• Frequency filters
• Tapering
• Field examples

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Frequency content of a shot
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Waves
Amplitude
Acos(2pft)
Acos(2pft-f)
t
t
Period
ltv
Wavelength
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Periodic and transient waveforms
Periodic waveform
Transient waveform
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Periodic waveforms

• Any periodic waveform, may be decomposed into a
  series of sine (or cosine) waves whose
  frequencies are integer multiples of the basic
  repetition frequency
• It is necessary to define not only the frequency
  of each component, but also its amplitude and
  phase

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Fourier transformation
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Summation of different frequencies
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Fourier transformation
A(f)
F (f)
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• frequency
• amplitude
• phase

f1
f1
f2
f2
Sum
Sum
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f1
f1
f2
f2
Sum
Sum
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Digital representation of continuous amplitude
and phase spectrum associated with a transient
waveform
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Spike function
DC bias
Transient waveforms approximating seismic pulses
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Frequency filter
Low Pass
High Pass
f
f
Notch filter
Band Pass
f
f
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Tapering
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Tapering of filters

• Butterworth
• Hanning
• Ormsby
• Amplitude and phase characteristics.

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Band-pass filtered raw field records
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Corrected for geometric spreading frequency
absorption remains