Repeatability requirements of seismic data
This section expands on some of the items listed in Section 2C. It is intended to impart a healthy suspicion of the effects of data processing parameters. These effects can be much reduced by well matching/wavelet extraction methods, but this should not be assumed. In differencing operations noise becomes much more of an issue!
Time-zero corrections and statics applications: The data must be repeatable in time. Just a millisecond of time shift allows root mean square (rms) amplitude differences of around 18% in a simple test. Fig. 4.A.1 shows a "final" processed migrated section from a 3D data volume. In the lower panel of the figure is a subtraction produced from the same section, time shifted from itself by 1 ms.
To show a more extreme example, consider the 4-ms shift shown in Fig. 4.A. 2. This produced a subtractive rms amplitude of 71% of the original data. We can conclude that time matching of seismic data is critical before its use as time-lapse data. Since many of our "final" sections exist at a sample interval of 4 ms, we have to ensure that any software used to compare several 3D data cubes has an interpolated time shift capability. Acquisition equipment and data processing time delays may easily impart a fraction of the final sampling interval
Mute applications: An early step in a processing sequence is often a first-break mute. This will be picked empirically from trial parameter tests and examination of the data. The effect of a small change