[OpendTect_Users] Time-depth horizon conversion

[Mike Stone]

You know, an approach I like better is to create a Time-Depth Volume
Attribute.
It's basically the same procedure except you create a reference stack of
time values and do a Avg * Ref/2 instead.

This way you can extract Depth Horizons directly rather then having to
calculate each one. If you have dozens of horizons this can be a real time
saver.

Of course this all assumes you have average velocities right?

Mike Stone
832-768-0884
MStone at ACT3Solutions.com


On Fri, Jul 1, 2011 at 4:52 AM, Farrukh Qayyum <farrukh.qayyum at dgbes.com>wrote:

> **
> Dear Emilson,
>
> We normally do an on the fly time to depth conversion of the seismic data
> using a velocity cube. However, if you want to convert only time horizons
> into depth horizons within OpendTect then you will have to do the following
> steps.
>
>    1. Go to Attribute set window (Main Menu > Analysis > Attribute > ...).
>    2. In the pop-up attribute set window, you will have to find Horizon
>    attribute in the list.
>     - Select that attribute and provide an input seismic data on which the
>       Horizon was being mapped.
>       - Select the horizon that you want to convert into depth.
>       - Do not change the default Output type. Please leave it 'Z'.
>       - Provide an output name to this horizon attribute (e.g. Horizon A).
>    3. The above step is done to get Z-values (in seconds) of a given
>    horizon and then multiply the attribute with a velocity data. The next step
>    is to do time to depth conversion:
>       - Now find the Mathematics attribute in the list. In the formula
>       bar, please type this: *HorZ * Vel/2*. Prese the *Set* button. Here,
>       we are using two variables. HorZ is the defined horizon attribute (Horizon
>       A) and the Vel is a stored Velocity data. If you do not have any velocity
>       data and you want to use a constant velocity, please replace the Vel
>       variable to any constant value e.g. 3000.
>       - Once you will press the *Set *button, it will ask you to provide
>       the inputs for HorZ and Vel variables. Please select the right inputs as
>       explained in the above bullet.
>        - Give an output name (e.g. Horizon A depth) to this attribute.
>       - Save the attribute set and press OK to the Attribute set window.
>        4. Now create the grid output (Main Menu > Processing > Create Grid
>    Output). In the pop-up window, please select the Quantity to output (here it
>    should be the attribute i.e. Horizon A depth). Then also select the horizon
>    for the *calculate on surface *field. Once done, press *Proceed*button.
>
> Please note that the horizon is saved as an attribute data (depth) on a
> selected horizon that can be exported as an ASCII grid. To export the
> attribute grid created in the step 4, you may use the export utility form
> the Main Menu > Export > Ascii .... In the *Export Horizon *window, select
> the horizon and the calculated attribute from the list and export it to a
> disk. This exported horizon can be used in the depth survey.
>
> Best Regards,
>
> Farrukh Qayyum
> Geoscientist
> dGB Earth Sciences B.V.
> Nijverheidstraat 11-2,
> 7511 JM Enschede, The Netherlands.
> Tel:	+31 53 4315155
> Fax:	+31 53 4315104http://www.dgbes.com
> mailto: farrukh.qayyum at dgbes.com
>
>
> On 06/30/2011 09:20 PM, Emilson wrote:
>
> Dear OpendTect users,
>
>
> Is there a way to convert time-horizons into depth-horizons within
> OpendTect?
>
>
> Thank you all,
>
> Emilson P. Leite
> DGRN/IG/UNICAMP
>
>
> _______________________________________________
> Users mailing listUsers at opendtect.orghttp://lists.opendtect.org/mailman/listinfo/users
>
>
> _______________________________________________
> Users mailing list
> Users at opendtect.org
> http://lists.opendtect.org/mailman/listinfo/users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.opendtect.org/pipermail/users/attachments/20110701/be68a8bd/attachment.html>