Hi Manabu -

I apologize for my late response ...

Thank you for your kind note.  The goal of my writings and YouTubes is to make something clear.  I am very glad I could do that for you regarding SEG-Y and SU trace header byte locations.

Regards, David
. . . . . . . . . . . . . .



On Sunday, October 23, 2022 at 04:30:54 PM MDT, <tanahashi.m@gmail.com> wrote:


Dear David, Seismic Rocks, LLC

 

Thank you for the information on your lecture movies about Seismic Unix on youtube channel.  I now understand the meaning of #180 and beyond in the SEG-Y trace headers and how to identify and handle it. 

 

Best regards,

 

Manabu Tanahashi

Tsukuba, Japan

 

From: David Forel <davidforel@yahoo.com>
Sent: Saturday, October 22, 2022 3:12 AM
To: seisunix@mailman.seismic-unix.org; dominique.rousset@univ-pau.fr; tanahashi.m@gmail.com
Subject: Re: [Seisunix] Re: How to handle trace header information?

 

Hi Manabu -

 

I have a YouTube channel (Seismic Rocks LLC) ( https://www.youtube.com/channel/UCp66KhTgHf1V6KfEfH2OnnQ ) that has a video about importing SEG-Y files that require "remap":

-  "Seismic Unix: Complicated SEG-Y Import"

 

Note that the description that goes with the video includes a link to a PDF of the same information.

 

Regards, David

. . . . . . . . . . . . . .

 

 

 

On Thursday, October 20, 2022 at 03:31:26 AM MDT, <tanahashi.m@gmail.com> wrote:

 

 

Dear Dominique,

 

Thank you for the reply to my question.

 

As  you suggested, I have to remap the inline and cross line numbers at #189-192 and #193-196 to the unused integer keyword.

 

I was also personally informed from my friend in Japan how to remap  trace header words during segyread.

 

segyread tape=Source3D.sgy remap=swdep,gwdep byte=189l,193l | suresamp rf=0.5|segyhdrs | segywrite tape=Output3D.sgy

 

The time resampled SGY data with inline and cross line numbers on #61-64 and #65-68 was obtained.

 

It is good enough to load resampled data into my interpretation system.

 

Thank you very much again.

Best regards,

 

Manabu Tanahashi

Tsukuba, Japan

 

From: Dominique ROUSSET <dominique.rousset@univ-pau.fr>
Sent: Thursday, October 20, 2022 5:35 PM
To: seisunix@mailman.seismic-unix.org
Subject: [Seisunix] Re: How to handle trace header information?

 

Hi,
In the SU format, the bytes you use for inline and cross line numbers are allocated to SU use (see sukeyword -o ; d2 and f2 are floats in SU). Bytes # 189-192 and # 193-196 are inline/crossline numbers in segy rev1 for 3D post stack data. SU is not 3D fully capable and  segywrite does not use them for segy rev0 output.

I tried this simple test.

suplane | sushw key=d2,f2 a=3,4  | segyhdrs | segywrite tape=plane.segy
segyread tape=plane.segy | surange

tracl    1 32 (1 - 32)
tracr    1 32 (1 - 32)
offset   400
ns       64
dt       4000
d2       0.000000
f2       0.000000

:-(

I don't see any solution at the user level without modifying segywrite to introduce header remapping à la segyread.

Within SU, I suggest that you use other keywords to store the inline and cross line numbers (such as swdep/gwdep, 4 bytes integers) and apply header remapping to read the
data in other software. Anyway, using bytes # 189-196 in SU will complicate data display.

suplane | sushw key=swdep,gwdep a=3,4  | segyhdrs | segywrite tape=plane.segy
segyread tape=plane.segy | surange

tracl    1 32 (1 - 32)
tracr    1 32 (1 - 32)
offset   400
swdep    3
gwdep    4
ns       64
dt       4000

D.

Le 20/10/2022 à 01:35, tanahashi.m@gmail.com a écrit :

Dear all,

 

I have performed a time resample of some 500ns sampled 3D seismic data to 1ms intervals using the suresamp command as shown below, but was unable to transcribe the 189-192 bytes of the Inline and the 192-196 bytes of the crossline numbers.

 

segyread tape=Source3D.sgy|suresamp rf=0.5|segyhdrs|segywrite tape=Output3D_1ms.sgy

 

I solved this problem by using the ASCII input/output function for trace header on SeiSee, a free Windows software, to write out the header information of the original file and then write it into the header of the output file.

 

Is there a way to transcribe inline and crossline numbers using the SU function?

 

Manabu Tanahashi

Tsukuba, Japan

 

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-- 
|Dominique Rousset           LFCR UMR5150 / E2S UPPA / Dpt des géosciences| 
|Univ. Pau et des Pays de l'Adour BP 1155       F-64013 Pau Cedex - France|
|mailto:dominique.rousset@univ-pau.fr               http://lfc.univ-pau.fr|
|   Off: +33 559 407 423                         Cell: +33 660 861 391    |

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