This describes the analysis of streamer feathering and SIOSEIS type 13 geometry. The streamer navigation must be described using the UKOOA P190 standard. Given an unknown seismic line the first thing to do is to plot the streamer position! Using SIOSEIS and MATLAB, the analysis follows: 1) Create a synthetic SEG-Y file that contains the UKOOA X-Y coordinates of the shot and receivers. 2) Print the X-Y coordinates of the shot and receivers. 3) Plot the streamer location using Matlab. 4) Find the "start of line". 5) Find the "end of line". 6) Create a synthetic file with SIOSEIS geom type 13. 7) Compare the feathering angle and crossline offset in the SEG-Y header and the plots from step 3. 8) Plot the crossline offsets vs survey distance. 9) Plot the streamer feathering vs survey distance. 1) Create a synthetic SEG-Y file that contains the UKOOA X-Y coordinates of the shot and receivers. sioseis << eof procs syn geom diskoa end syn ntrcs 240 secs 1 fno 10479 lno 11050 tva .5 10000 1 end end geom dbrps 12.5 navfil GOC14.240.p190 type 13 end end diskoa opath syn.line14 end end end 2) Print the X-Y coordinates of the shot and receivers. more prt #! /bin/csh @ N = $1 sioseis << eof procs diskin prout end diskin fno $N lno $N allno no ipath syn.line14 end end prout indices l3 l4 l19 l20 l21 l22 format (6(1x,F10.0)) fno 0 lno 9999999 end end end Comments: Redirect stdout (e.g. prt 10579 > l.10579), then edit the output file so that it conatins only numbers (don't forget the last line of the file). 3) Plot the streamer location using Matlab. load l.10579 x = l(:,5); y = l(:,6); a = min(x); b = min(y); x = x-a; y = y-b; sx = l(1,3) - a; sy = l(1,4)-b; plot(x,y,'b.',sx,sy,'r*') axis([-1000 7000 -1000 7000]) grid on title('10579') Plots of the streamer at shots: 10579 10679 10779 10879 10979 4) We really need to see the shot-line, so a similar sioseis job: procs diskin prout end diskin fno 10601 lno 11000 ftr 1 ltr 1 allno no ipath syn.line14 end end prout indices l3 l4 l19 l20 l21 l22 i48 i49 format (8(1x,F10.0)) fno 0 lno 9999999 end end end and add to Matlab: load l.all ax = l(:,3) - a; ay = l(:,4)-b; hold plot (ax,ay,'g-') Plots of the streamer feathering are: 10779 10879 10979 Plots of the streamer cross-line offset are: 10779 10879 10979Return to SIOSEIS examples. Go to the list of seismic processes. Go to SIOSEIS introduction.