Using seisazi.m to display azimuth headers

Examining header dumps can be tedious, so an alternative graphical scan helps evaluate the tool orientation solution. In the directory with the Lxxx.seg files, we can pull off selected channels of the data (using bmrg) and then plot the geophone azimuth header using Octave. To extract the channel 2 component for the odd shots, we give the commands:

bmrg L 1 146 2 2 2
mv bmrg.seg bmrg0002.seg

To extract the channel 3 component for odd shots

bmrg L 1 146 2 3 3
mv bmrg.seg bmrg0003.seg

We don't need more than either the odd or even channels because the tool is fixed for the two source polarizations at each depth. Insertion of the azimuth determinations will be identical for any odd-even pair at the same depth. We start an Octave session and execute the following command from within the Octave text window

seisazi;

One responds to the GUI dialog prompts for file name. Note that seisazi.m requires both segyinfo.m and bsegin.m to be installed in the directory with the data. One either sets up a path to the *.m files, or copies them from /usr/local/share/octave/site-m. Combining two runs of seisazi.m results in Figure 14

Figure 14: Plot of channel 2 and channel 3 geophone azimuth headers. The apparent discontinuity at about 12.5 m depth is exaggerated by channel 3 passing through North, 0 deg. = 360 deg.