LOADING 2-D SEISMIC DATA
Created by J. S. Curry /
2D Data set is from the Timor
Sea, NW Shelf of Australia in collaboration
with the Australian Geological
PART I: CREATE PROJECT
A) Under the Openworks
4.1 Command Menu select Project/Project Create,
fill in the window creating a master project and apply.
B) Next, from the Openworks 4.1
Command Menu select Project/Seismic Project/Seismic
Project Create, add a seismic project to your
master project and hit create.
PART II: COPY DATA FROM MAGNETIC
A) Using copytod,
from a terminal, follow the example
below; telnet to wilcox (where tape drive is located), login to dataload
and enter password. Type setenv in the terminal and type the name of the
directory to copy files to (i.e. master project directory name). Type copytod
and select project 2D or 3D, directory (select global), and select tape
to tod file. Enter r, then give the tod file a name (example - xyz123).
Next select number of files you want to skip on the tape ( none to get
the first line, one to get the second, etc.), use defaults for the rest
of the choices (tod files take about 5 min. to copy).
PART III: CHECK
HEADER INFORMATION ON .tod_glb FILES
A) From a terminal window,
type segychk. Specify tape-on-disk file, give output file a name so you
know what .tod file it is for (a .lst file is created), specify global
to look for the .tod file in your project directory (or current directory
if running segychk from the project directory), then enter the name of
the .tod file (excluding the 01.tod_glb extent) and type c to continue.
See example below;
B) After segychk has run,
you can type de to view the EBCDIC header like the example below;
Command E exits and saves
header to .lst file. You can also type db to view the binary header.
PART IV: FORMAT NAVIGATION
A) You will need to create
three files containing the following information; first and last shotpoint
for each line, shot point to trace relationship, and X & Y coordinates
PART V: CREATE
1) lineinfo.csv - (first
and last shotpoint for each line) this information can be obtained from
the EBCDIC header on tape (see fourth line on header from step III) or
from the header on the paper copy. Make
sure each column contains the same number of characters on each line (in
the example below, zeros have been added in front of the last column to
even the number of characters)!!!! The
first column contains the line name, the second column contains the first
shotpoint, and the last column contains the last shotpoint. Example;
2) sptrace.chk - (shotpoint to trace
relationship) this information can be obtained from the header. Again,
make sure to format columns with the same number of characters for each
line!!! The first column contains the
line name, the second contains shotpoint numbers, and the third column
contains the trace number corresponding to the shotpoint numbers (the example
below shows that the shot to trace relationship is one-to-one).
3) navdat.csv - (X & Y coordinates
for shotpoints) this information is obtained by the company which is supplying
the dataset. Data will probably need to be converted from lat/long to X
& Y coordinates. This can be done easily using mapproject.sh. Open
the resulting file in Excel and format cells so that each column contains
the same number of characters (the example below displays every 100th shotpoint
and the corresponding X & Y coordinates, other decimation factors can
be used on this data).
From the Openworks 4.1
Command Menu select Data/Import/2D Seismic
Basemaps. From map menu select Map
Session/Read ASCII Files. In the Read ASCII
window, enter files from step IV above by clicking the list button for
each file type, and entering the full file path. Type 1 is the first file
from step IV (lineinfo), type 2 is the second (sptrace), and type 3 is
the third (navdat).After selecting the file path, click on type 1,2,or
3 at the top of the screen. The file will appear in the window. Specify
the spaces for each column in the file, this can be done by clicking the
button in front of line name and highlighting the line name in the file
window at the top of the screen, then minimum trace, etc. When all three
files are done, hit Read Files. This will create three files for each line
in the project directory (.lh,.st, and .xy).
B) Next, choose Map
Session/Choose Any Lines and select the lines
you want to display in the basemap and click display in map. You should
now have a basemap display similar to that below.
PART VI: BATCH
CONTROL MONITOR (bcm2d)
A) Modify a copy of load2d.pcf
to your tape on disk files. Specify the name of your .tod file under INPUT/todfile
(replace clas2d01). Under signal specs, specify the sample format (-2 for
IBM floating point, -3 for IEEE floating point), sample rate (in msec),
and beginning and endind time of your data. Next specify what line of the
header the program will find the tracenumber on ( line 25 in example),
and give the line a name ( example DGS-101). Run a sample line a couple
of times with different values under histogram to determine the range of
amplitudes in your data. This will help you determine the scaling factor
for the final run of bcm2d. Specify a sample format under DISKOUT (use
8,16,or 32 bit). Save changes and close the file in your home directory.
B) From a terminal window,
type bcm2d, then the .tod file you want to use. Enter e for execute phase.
The output of bcm2d will be a stk(8,16,or 32)0001.2v2 file in your master
project directory, and a .lst file in your home directory. Open the .lst
file and view the histogram to determine the scaling factor to use.
C) Now use the amplitude value which
makes up the 98th percentile from the histogram. In the example above that
value is 3500. So we can apply a scaling factor to the .pcf file and run
bcm2d again. In the .pcf file, enter .SCALE and factor (tab) 127 (tab)
3500 and clip amplitudes above 3500 to + or - 127 (maximum screen can display).
PART VII: ADD
LINES TO PROJECT
A) From the Openworks 4.1
Command Menu, select Project/Seismic Project/Seismic
Project Modify. Select the project name and
click OK. Highlight the lines in the available lines to add window that
you wish to add to the project and click the add lines button.
B) Another window will
appear. Select Update 2D Working Project Files
and Catalogs, meters or feet, and hit OK.
Dataloading is done. Now you should be able to open
Seisworks and view the lines you just loaded.