[OpendTect_Users] Few questions on 3D horizons

[Michael Heeremans]

 On Tue, 10 May 2011 13:33:14 +0200, Kristoffer Rimaila 
 <kristoffer.rimaila at dgbes.com> wrote:
> Dear Michael,
>
> Hopefully the points below will answer your questions.
>
> 1) Two horizons can be merged through using the 'horizon' and
> 'mathematics' attributes. First, output 'z' of the horizons with the
> 'horizon' attribute (select 'Positions' and 'Horizon' in the 3D
> attribute set).  You will also need to select input seismic here.
> Next, use the 'mathematics' attribute to merge the two (or more)
> attributes created from your horizons. For example, you can use the
> following formula: horizon1 == undef? horizon2:horizon1 if your
> horizons contain 'empty space' within your inline/crossline range,
> i.e. undefined data. Give a name  and save. If the horizons you want
> to merge are overlapping you will need to accommodate for this in 
> your
> mathematics attribute. For example you can specify the attribute to
> deal with overlap with the following formula: horizon1 > horizon2?
> horizon1 : horizon2 or vice versa, depending on which of the
> overlapping horizon-portions you wish to keep. Then use this 
> attribute
> as input when you 'set' the formula for the merge attribute. If you
> ignore to take the overlap into account, the z value of your merged
> horizon will be the z-value of horizon1 + z-value of horizon2, i.e.
> double. After creating the merging attribute, go to 'Processing' in
> the main menu, select 'Create Grid Output' --> 'Grid' ---> '3D...'.
> Here, choose the merged attribute created with the formula, give new
> name and choose which surface to use as reference ('Calculate on
> surface').

 I have to admit, that this description was not very straight forward. I 
 will try a few times more, but can't you just merge two 3D grids?

 Michel


>
> After gridding the attribute, go to 'Survey' (main toolbar) -->
> 'Export' --> 'Horizons' --> 'ASCII 3D'. Select the merging
> (mathematics) attribute, set area subselection (optional) and for
> 'Output Z' choose 'No'. Give output name and hit 'Go'. The new, 
> merged
> horizon can then be imported similarly in the main toolbar through
> 'Survey' --> 'Import' --> 'Horizons' --> 'Ascii' --> 'Geometry 3D'.
> Here, select the exported file. It should not contain a header. 
> Define
> the format (z-units are in seconds!). Scan input file (optional), 
> give
> output name and hit 'Go'. The merged horizon can now be loaded in the
> tree.
>
> The workflow above is obviously time consuming and complicated.
> OpendTect version 4.3 (which will be released after the EAGE
> conference in two weeks) deals with merging horizons in a much 
> simpler
> way; you can use the 'set z-values' tool under algorithms in the tree
> to convert a grid into a horizon or apply a shift, stored as a grid 
> to
> the horizon.
>
> 2) For more information on how to track/edit a horizon, please refer
> to chapter 3.3 of the OpendTect user-documentation manual. It can be
> found on the dGB support site:
> 
> http://opendtect.org/rel/doc/User/base/chapter3.3_interpret-horizons.htm#LINK-TRACKING.SETUP
>
> 3) It is possible for multiple persons to work on the same project.
> To do this, I would suggest you set the data-root (ODData) to the 
> same
> network location on all of the computers you wish to work on. To 
> avoid
> file conflicts with edited horizons, faults etc. the first thing to 
> do
> would be to open the files and 'save as..' and create separate files
> for each interpreter, using initials in names as id for instance.
>
> If you have any further questions, please do not hesitate to contact 
> me.
>
> best regards,
>
> -- Kristoffer Rimaila
> -- Geoscientist
> -- dGB Earth Sciences
> -- Nijverheidstraat 11-2, 7511 JM Enschede, The Netherlands
> -- mailto: kristoffer.rimaila at dgbes.com, http://www.dgbes.com
> -- Tel: +31 53 4315155 , Fax: +31 53 4315104
>
>
> On 9-5-2011 14:47, Michael Heeremans wrote:
>>   Hi,
>>
>>   I have a few questions regarding 3D Horizons and 3D horizon 
>> tracking
>>   and hope that someone can help me with that:
>>
>>   1) How can a merge 2 horizons into 1 horizon.
>>
>>   2) When I have tracked a few in- and crosslines using the line 
>> tracker
>>   option for 3D horizons, I change to Volume tracker to fill in the 
>> rest.
>>   When I then want to edit this automatic interpretation and use the
>>   Auto-track option, does it overwrite my earlier interpreted seeds? 
>> If
>>   so, what is the best workflow for interpreting and editing a 3D 
>> horizon?
>>
>>   3) Is it possible for two person to work simultaneously on the 
>> same
>>   project or will this lead to that OD crashes?
>>
>>   Best regards, Michel
>>

-- 
 Dr. Michel Heeremans

 Data Management and Geoscientific Software support
 Department of Geosciences, University of Oslo
 PO Box 1047 Blindern, 0316 Oslo, Norway
 Room 205, Geology Building
 tel: +47 228 56615, mob: +47 99 434 968, fax: +47 228 54215
 e-mail: michael.heeremans (a) geo.uio.no