Page 166 - Acquisition and Processing of Marine Seismic Data

2.6 QC IN DATA ACQUISITION 157

FIG. 2.102 Near-field hydrophone outputs of two identical strings, (A) string number-1 and (B) string number-6, both con-
sisting of six guns.

Another QC implementation for seismic source array firing alternatively, e.g., 1 for port
source is to verify the gun flag in case of flip-flop array and 2 for starboard array. As the acquisi-
acquisition which is standard operation for 3D tion continues, the gun flag is stored in the nav-
NAZ surveys today. In flip-flop acquisition, port igation log file to signify which array is fired at
and starboard source arrays are fired alternately, which shot point. Log files are checked for each
in which port array is fired at odd numbered line to ensure that the firing of the sources is
shot points, while starboard array is fired at consistent for whole line. Alternatively, coordi-
even numbered shot points (Section 2.3.5). The nates of all shot points are plotted to verify the
gun flag states the number of the individual flip-flop shooting (Fig. 2.103).