[Seisunix] su to segy

[Hussain I. Hammad]

Hello everyone,

 

This might seem to be a basic issue, but for some reason things don’t work!

 Attached is a sample shot in SU format. I tried the following to convert it to segy:

 

------------------

segyhdrs ns=200 dt=4000 < subsamp.su

segywrite  tape=subsamp.sgy endian=0 verbose=1 < subsamp.su

rm  binary header

-----------------

 

The SEGY file gets written, but not correctly. I would appreciate your help.

 

Thanks,

Hussain-

 

[Vincent Vandeweijer]

? I'm sorry, looks fine from here... (exept that you might need to
reset d2). I'm running the commands below from a little endian (linux)
machine... What is you'r exact problem ?

<<<snip>>>
[vandeweijervp@cincinnati ~]$ surange < subsamp.su

450 traces:
tracl 1 450 (1 - 450)
tracr 1 450 (1 - 450)
trid 1
offset -1 4489 (-1 - 4489)
sdepth 50
sx 1
gx 0 4490 (0 - 4490)
ns 200
dt 4000
d2 10.000000
[vandeweijervp@cincinnati ~]$ segyhdrs < subsamp.su

[vandeweijervp@cincinnati ~]$ segywrite tapesubsamp endian0
verbose1 < subsamp.su

segywrite: tape opened successfully
segywrite: header file opened successfully
segywrite: binary file opened successfully
segywrite: header file closed successfully
segywrite: 50 traces written to tape
segywrite: 100 traces written to tape
segywrite: 150 traces written to tape
segywrite: 200 traces written to tape
segywrite: 250 traces written to tape
segywrite: 300 traces written to tape
segywrite: 350 traces written to tape
segywrite: 400 traces written to tape
segywrite: 450 traces written to tape
segywrite: tape closed successfully
segywrite: binary file closed successfully
[vandeweijervp@cincinnati ~]$ segyread tapesubsamp | surange

1+0 records in
6+1 records out
3200 bytes (3.2 kB) copied, 0.000558 seconds, 5.7 MB/s
450 traces:
tracl 1 450 (1 - 450)
tracr 1 450 (1 - 450)
trid 1
offset -1 4489 (-1 - 4489)
sdepth 50
sx 1
gx 0 4490 (0 - 4490)
ns 200
dt 4000
d2 0.000000
<<<snip>>>

regards,

Vincent

On Mon, Oct 19, 2009 at 1:55 AM, Hussain I. Hammad <hiha...@ucalgary.ca> wrote:
> Hello everyone,
>
>
>
> This might seem to be a basic issue, but for some reason things don’t work!
>
>  Attached is a sample shot in SU format. I tried the following to convert it
> to segy:
>
>
>
> ------------------
>

> segyhdrs ns 0 dt@00 < subsamp.su
>
> segywrite  tapesubsamp.sgy endian0 verbose1 < subsamp.su

>
> rm  binary header
>
> -----------------
>
>
>
> The SEGY file gets written, but not correctly. I would appreciate your help.
>
>
>
> Thanks,
>
> Hussain-
>
>
>

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>

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[Hussain I. Hammad]

Thanks to all who responded.

The problem, as Vincent pointed out, is in the header value d2. The fix is
to reset it to zero and then convert to SEGY.

Here is the code, for the archive:

--------------------
sushw < subsamp.su key=d2 a=0.000 > subsamp_hdr_rest.su

segyhdrs ns=200 dt=4000 < subsamp_hdr_rest.su

segywrite tape=subsamp.sgy endian=0 verbose=1 < subsamp_hdr_rest.su

-----------------

I am not sure why the original code worked for some and did not work for me.
I tried it on two different versions of SU, one is a bit old and the other
is recent.

Thanks a lot,

[John Stockwell]

1.) what type of computer are you running on (32 or 64 bit)?
2.) what operating system are you running on?
3.) did you install SU with the options
4.) In what way is the segy output "not right"?

If your input traces have headers, then you do not need to set
dt and ns in segyhdrs.

John Stockwell | jo...@dix.Mines.EDU
Center for Wave Phenomena (The Home of Seismic Un*x)
Colorado School of Mines
Golden, CO 80401 | http://www.cwp.mines.edu/cwpcodes
voice: (303) 273-3049

Our book:
Norman Bleistein, Jack K. Cohen, John W. Stockwell Jr., [2001],
Mathematics of multidimensional seismic imaging, migration, and inversion,
(Interdisciplinary Applied Mathematics, V. 13.), Springer-Verlag, New York.