Setting Geometry Bison Data: [genref-> geom->geom2(go1)]

The program genref is an interactive program to aid in setting geometry. It creates files geom, geom2, go1, *.xyz, *.nez. For example, type genref from a text window. The following is a captured log:


{genref}
  CDP Roll-a-long Pattern Generator 
  Bison Format Data
  
 -----------SOURCES-----------------------------
   Enter 6 char. name for nez file (ex. STP001)
REF001
   Enter 4 char. LINEID
0001
   Enter Z-Datum: Elevation
500.
   Enter number of shots 
1
   Enter Shot Record Names 8char: First
LOST0001
   Enter Shot Record Names 8char: Last
LOST0001
  Enter First Shot Station Number
01
   Enter First Source: x, y, z
0, 0, 100.
   Enter Last Source: x, y, z
0, 0, 100.
  Enter number of receivers in a shot gather
12
  Enter TOTAL NUMBER of stations on line
12
   Enter First Geophone Station: x, y, z
0, 140., 100.
   Enter Last Geophone Station: x, y, z
0, 250., 100.
  Enter first shot NEAR GEOPHONE station
01
  Enter first shot FAR GEOPHONE station
12
genref


In this example, there is only one shot gather, Bison file named LOST0001. We are creating an *.nez file, REF001.nez. The Z-Datum is the elevation that all following elevations are measured from. Here, we set that to 500. Then later, the geophones and shots are specified as being 100. meters above that (final elevations are thus 600. meters). The generated file, REF001.nez is:


{name1}
0001            0.0000      0.0000    600.0000  SP001
0001          140.0000      0.0000    600.0000  VP001
0002          150.0000      0.0000    600.0000  VP002
0003          160.0000      0.0000    600.0000  VP003
0004          170.0000      0.0000    600.0000  VP004
0005          180.0000      0.0000    600.0000  VP005
0006          190.0000      0.0000    600.0000  VP006
0007          200.0000      0.0000    600.0000  VP007
0008          210.0000      0.0000    600.0000  VP008
0009          220.0000      0.0000    600.0000  VP009
0010          230.0000      0.0000    600.0000  VP010
0011          240.0000      0.0000    600.0000  VP011
0012          250.0000      0.0000    600.0000  VP012
name1


The generated files geom, geom2, go1 must be set to executable using the command
chmod +x g*
(assuming there are no other files starting with the letter “g”). File geom has a record for each shot. Here, there is only one line:


{name2}
topcon REF001.nez LOST0001 0001 0.0  1 12 001 012   1  0.   0   0   0   0
name2


The call to topcon captures sample interval, number of samples, date of shooting, etc from LOST0001, the Bison file. It combines that information with the REF001.nez file geometry to create a file LOST0001.xyz which is then needed later by script go1 which is called from geom2 shown next:


{name3}
go1 001
name3


Here is the script go1:


{name4}
 bis2seg LOST0$1
 bhed LOST0$1.seg LOST0$1.xyz 0
mv bhedLOST.seg L$1.seg
rm LOST0$1.seg
name4


$ In summary after running genref, make the scripts executable and run them in sequence (geom, then geom2).

The result will be file L001.seg in this example. The program bdump produces a partial listing of the headers:


{name5}
 
                     |-------------------------------|
                     |   PARTIAL SEGY HEADER DUMP    |
                     |                               |
                     |           L001.seg            |
                     |                               |
                     |-------------------------------|

 -----------------------------------------------------------------------------------
   Length =  2000 samples             |  Shot Elevation =      600.0
   Sample Interval =    0.00020 sec.  |  Shot Depth =        0.0
   Delay Time =    0 msec.            |  Up Hole Time =     0 msec
   Low Cut Filter  =   16 Hz.         |  Shot X-COORD =       0.00
   High Cut Filter =  500 Hz.         |  Shot Y-COORD =       0.00
   Line ID: 0001                      |  Shot Date (year.moday) = 1992.0303
   Shot Orientation:                  |  Shot Time (hr:min)   = 17:07
   Azimuth=  0 Deg.  Vertical=  0 Deg.|  Charge Size (grams)=     0
 -----------------------------------------------------------------------------------
 TRACE|SHOT| STATION | OFFSET|        RECEIVER          |VERT|1STBRK|K-GAIN|AZI|VER|
   #  |REC.|SHOT  REC|       |  ELEV.  X-COORD   Y-COORD|FOLD|(SEC.)| (dB) |   |   |
 -----|----|---------|-------|----------------------------|--|------|------|---|---|
    1 |   1|001  001 | 140.00|  600.00      0.00    140.00| 1|0.0000|   60 |  0|  0|
    2 |   1|001  002 | 150.00|  600.00      0.00    150.00| 1|0.0000|   60 |  0|  0|
    3 |   1|001  003 | 160.00|  600.00      0.00    160.00| 1|0.0000|   60 |  0|  0|
    4 |   1|001  004 | 170.00|  600.00      0.00    170.00| 1|0.0000|   60 |  0|  0|
    5 |   1|001  005 | 180.00|  600.00      0.00    180.00| 1|0.0000|   60 |  0|  0|
    6 |   1|001  006 | 190.00|  600.00      0.00    190.00| 1|0.0000|   60 |  0|  0|
    7 |   1|001  007 | 200.00|  600.00      0.00    200.00| 1|0.0000|   60 |  0|  0|
    8 |   1|001  008 | 210.00|  600.00      0.00    210.00| 1|0.0000|   60 |  0|  0|
    9 |   1|001  009 | 220.00|  600.00      0.00    220.00| 1|0.0000|   60 |  0|  0|
   10 |   1|001  010 | 230.00|  600.00      0.00    230.00| 1|0.0000|   60 |  0|  0|
   11 |   1|001  011 | 240.00|  600.00      0.00    240.00| 1|0.0000|   60 |  0|  0|
   12 |   1|001  012 | 250.00|  600.00      0.00    250.00| 1|0.0000|   60 |  0|  0|
name5


If there are any problems, or if one wishes to customize the geophone or shot orientations, that can be done by editing the *.xyz file and rerunning geom2. For setting down-hole data, see 6.7.5.