Page 300 - Acquisition and Processing of Marine Seismic Data

5.7 TRACE EDIT 291

FIG. 5.54 An example filtered shot with timing issues. (A) Shot number 1027 is delayed approximately 350 ms, possibly
due to a triggering delay between the recording unit and the gun controller. (B) After the trace kill, shot 1027 is removed from
the dataset. (C) Shots with static time delays can be distinguished by their odd appearance on the common offset sections.

controller. Because this time delay is generally the dataset by killing all traces of the shot
arbitrary, it may not be possible to determine (Fig. 5.54B). Missed shots and the shots with
the exact timing of the delayed shot to correct timing issues can easily be determined by
the time delay by a manual static time shift. inspecting odd traces on single trace sections
Fig. 5.54A shows an example shot gather for (Fig. 5.54C), which appear as traces inconsistent
the delayed shot issue. Here, shot 1027 is with the neighboring traces.
delayed approximately 350 ms, which means Sometimes swell noise is extremely effective
that either the recording unit is triggered on a number of successive channels and induces
350 ms before the guns are fired, or the gun very high-amplitude noise, appearing as narrow
array is fired 350 ms later than its expected vertical stripes extending from zero time to the
aim point for this shot. Because the determined end of the recording on the shot gathers. In most
delay is approximate, this shot is removed from cases, the issue is that a small part of the