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Book Chapter

Taiwan: Gain-Filter, Filter-Gain

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Published:
January 01, 2005

Abstract

We now have 5 seconds of Taiwan data and we zeroed the bad hydrophones. In this chapter we will

  1. apply spherical divergence correction, then band-pass filter the data. We will also

  2. apply a band-pass filter, then apply spherical divergence correction. We will compare gathers from these two paths and consider whether one path is better.

To determine which exponential gain to apply to the line of CMPs, we will apply gain to two shot gathers: 820 and 930̤ We window them from the 2-D line:

We will determine a tpow value for sugain by using script igain (Section 10.5), option T. Below is the user area of igain.sh changed for the Taiwan data.

The script creates three displays:

  • a wiggle plot of the file,

  • a decibel (dB) ximage plot of the user-selected trace(s), and

  • an amplitude graph of the user-selected trace(s). Remember:

  • The script applies gain to the entire file, but only the user-selected trace or traces are used to create the second and third displays.

  • The user is asked to supply the name of a key (offset, tracr, etc.) and corresponding key minimum and key maximum values for the second and third displays.

We selected key tracf and supplied tracf values 92 93 for both shot gathers, based on our displays in Chapter 12.

After several trials, we decide to use a spherical divergence correction of 1.8 (Figures 13.1 and 13.2).

We apply spherical divergence correction with the command below.

To select frequencies

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Figures & Tables

Contents

Society of Exploration Geophysicists Course Notes

Seismic Data Processing with Seismic Un*x: A 2D Seismic Data Processing Primer

David Forel
David Forel
Michigan Technological University
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Thomas Benz
Thomas Benz
Michigan Technological University
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Wayne D. Pennington
Wayne D. Pennington
Michigan Technological University
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Society of Exploration Geophysicists
Volume
12
ISBN electronic:
9781560801948
Publication date:
January 01, 2005

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