Page 314 - Acquisition and Processing of Marine Seismic Data

5.9 f-k DIP FILTERS 305

particular seem to be isolated from most of the portion of a noise record. Cable noise may be
linear correlated noise components. Fig. 5.68B in both directions from near to far or far to near
shows the output of the f-k filter applied to the channels (Section 3.6.2); the former produces
shot in Fig. 5.68A, which is designed to pass only positive dip linear events on the f-k spectrum,
reflection amplitudes while suppressing all while the latter creates negative dip. Although
other types of amplitudes. The f-k spectrum these events form a checkerboard appearance
involves almost only amplitudes of primary in time domain data (Fig. 5.69A), they can easily
reflections and the S/N ratio is significantly be discriminated in the f-k domain according to
increased in the output shot gather (Fig. 5.68B). their different dips (Fig. 5.69B and C).
Fig. 5.69 shows an analysis of mechanical Guided waves and seismic interference can
cable noise using the f-k spectrum of the deep also be analyzed in the f-k domain. Fig. 5.70A

FIG. 5.69 Analysis of mechanical cable noise using the f-k spectrum of a noise record. (A) Deep portion of a filtered noise
record (bottom) with significant cable noise in both directions and its f-k spectrum (top), after an f-k filter to make (B) negative
dip and (C) positive dip cable noise clearer.