[OpendTect_Users] OpendTect 2D horizon picking problem

[Antonio Klein]

Dear Collegueas
I would like to know if there is a course to beeginner in the Opendtect in
this year and if do you have any plan to do may be in Brazil. In southern
Brazil (Florianopolis, SC).
Cheers
Antonio




2012/2/4 Bert Bril <Bert.Bril at opendtect.org>

> Hi all,
>
>
> Juan wrote:
>
> > In my opinion, the problem that Guillaume has discovered and the issue
> > with the trace numbering that you described is extremely interesting for
> > me.
> >
> > This is the kind of problems that one (I at least) would like to read and
> > that often, sooner or later, one is confronted with. A couple of years
> ago
> > I faced a similar problem because the headers were incorrectly filled.
> > After correcting the headers all problems disappeared.
>
> I can say the following about this problem: Try using the development
> release 4.3. You will find it has a nice display of your header field
> values. In the graph you can easily see whether there are strange
> numbers, duplicates, and so forth. You can then choose a nice continuous
> number as identification (the 'Trace number' is what we call this
> identification number in OpendTect). Usually the CDP number is used,
> sometimes a SP number will be OK. Constraints are:
>
> 1) The number must continuously go up - or continuously down
> 2) The trace numbers can have a step different from 1, and that step
> doesn't even have to be constant. It is supposed to be proportional to
> the distance along the line, however.
> 3) Very damaging are trace numbers that duplicate, jump the wrong way or
> otherwise violate above rules. Then you'll get trouble.
>
> In all cases, be sure about what header value you use as trace number.
> Examine a large number or all of the traces, to do that click on the
> field in the table. Investigate discontinuities. Every point that is
> drawn is a potential discontinuity. I've sketched a few typical patterns
> below.
>
>
> What to do if you can't find a good trace number in the headers? Then
> make one! Also in 4.3 is the new 'Manipulate' button. You can create a
> new SEG-Y file from the old one with new, calculated header values. This
> works similar to the Mathematics attribute, just define some kind of
> formula using the other header values. A special case is 'INDEXNR' which
> is the sequence number of the trace in the file. A formula like:
>
> INDEXNR * 2 + 99
>
> will result in values 101 103 105 ...
>
> The result is immediately displayed, so you can check whether the new
> value is as you would expect it.
>
>
> Note that this new functionality will also be in the coming stable 4.4
> release (expected around the EAGE conference).
>
>
>
> Typical patterns (put your e-mail viewer in a fixed-width font):
>
>         o
>        .
>       .
>      .
>     .
>    .
>   .
>  .
> o
>
> or
>
> o
>  .
>   .
>    o
>       o
>        .
>         .
>          .
>           o
>
> Good trace numbers for 2D lines. The 2nd one has one missing trace
> number, which is OK when that's exactly what's the case: a gap.
>
>           o
>          .
>         .
>     o  .
>    .  o
>   .
>  .
> o
>
> A reversal. Not OK. Typically you are using the SP number in a line
> that's not re-sorted.
>
> oo
>  oo
>   oo
>    oo
>     oo
>      oo
>       oo
>
> Duplicate traces. Only the first one of each trace pair will be loaded,
> because OpendTect must make sure that every trace number is unique.
>
>               o........o
>       o.....o
> o....o
>
> or
>
> o.....o
>        o.....o
>               o.....o
>
> These patterns are typical for the inline number of a 3D survey.
>
>
>      o     o     o
>     .     .     .
>    .     .     .
>   .     .     .
>  .     .     .
> o     o     o
>
> ... and this one the crossline number of a 3D survey. Also, for
> pre-stack data this happens for offsets for each gather.
>
>
>      o...o              o
> o...o     o.o      o...o o..
>              o....o
>
> Typical for some kind of gain value. Not useful as trace number.
>
>
>
>
> Bert
>
> --
> -- Bert Bril / OpendTect developer at dGB
> -- mailto:Bert.Bril at opendtect.org , http://opendtect.org
>
>
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>



-- 
Antonio Henrique da F. Klein, Dr
Prof. Adjunto I (Oceanografia Geológica)

Universidade Federal de Santa Catarina
Centro de Filosofia e Ciências Humanas
Departamento de Geociências
Laboratório de Oceanografia Costeira

Campus Universitário - Trindade
Florianópolis, SC - 88040-900
Brasil

Fone: VOIP 48 3721 4112
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