Page 296 - Acquisition and Processing of Marine Seismic Data

5.7 TRACE EDIT 287

P
FIG. 5.49 (A) An example seismic line extending from the shallow continental shelf to deep abyssal plain with t gain of con-
P
stant P value (P ¼ 3) applied to whole data. (B) Same line with t gain with slightly increasing P values downslope from 2.2 to 3.0.
5.7 TRACE EDIT • contain powerline harmonic noise
interference (Fig. 5.50),
Trace edit is one of the earliest methods • are completely nonfunctional (Fig. 5.51),
for removing noise from the data. Commonly, • have very distinctive spike-like noise
not all of the recorded traces are usable. If (Fig. 5.52),
the noise level on a specific trace, or on a • belong to missed shots or autofires (Fig. 5.53),
number of traces, is dramatically high and it • have uncertain static time shifts (Fig. 5.54),
is not possible to remove it using available • are contaminated by extreme swell noise
processing techniques, then the trace is killed: (Fig. 5.55),
that is, the amplitudes of the trace are simply • have acquisition issues such as streamer
zeroed out. This operation is termed trace kill, bending (Fig. 5.56),
and it is generally applied to the channels • have other issues, such as gun timing errors
which specified as bad channels or shots.