Z-slice in 3D Horizons

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Maria Eulália Alberton

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May 26, 2025, 9:10:51 AMMay 26
to OpendTect Users
Dear Users,

I'm trying to get a Z-slide in reflectors below the first one, in an attemp to reconstruct paleobathymetry. I'd like to know if there's a reccomended way to do it, as I tried the manual and automatic way of tracking and it doesn't generate an entire horizon to generate the z-values, even in parallel reflector. I also tried to apply cosine phase attribute to see if the horizon recogniton gets easier, but I still couldn't do it.  In attachment is part of my OpendTect screen display.

Thank you so much for your attention,  I look forward for your reply 

Best regards,
Maria Eulália Alberton

telaod.png

Paul de Groot

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May 26, 2025, 9:33:21 AMMay 26
to us...@opendtect.org
Hi Maria,

If I understand you correctly you want to slice through the seismic data parallel to the seabed reflector. This can be done in two ways:
  1. Right-click on the horizon entry in the tree (or in the scene) and select Workflows -> Create Flattened Scene. (Alternatively, you can launch this from the Scenes->New[Horizon Flattened]->3D menu.) In the flattened scene add a time-slice (or a volume viewer so you can movie-style inspect time-slices)
  2. Right-click on the horizon in the tree (or in the scene) and select Tools -> Shift ... In the window that pops up select the seismic data and Calculate. Now, you can use the slider to inspect the seismic amplitudes extracted parallel to the input horizon in the specified time-gate. Note that as you slide up and down, the horizon in the tree changes its name to reflect the vertical shift. You can save each shifted horizon as a new horizon in the database. 
Best regards,

Paul.

--
Paul de Groot
Special Adviser


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dGB Earth Sciences
Phone:+31 53 4315155
E-mail:paul.d...@dgbes.com
Internet:dgbes.com 
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Maria Eulália Alberton

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May 26, 2025, 1:21:04 PMMay 26
to us...@opendtect.org, Paul de Groot
Dear Paul,

I'm trying to extract using a reflector parallel to the seabed reflector only for testing, but I need to extract the Z-slice in deeper reflectors and preferably in the ones I can identify in my interpretation, not only parallel ones. I've already tried to use a time slice, but as I need to reconstruct a paleosurface, this method isn't so interesting for this project. So, I'd like to know if there's a recommended way to do it, since when I try to trace the new horizon, it's never available to generate the slice.

Thank you so much for your attention and availability,
Best regards,
Maria Eulália Alberton
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Paul de Groot

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May 26, 2025, 2:48:00 PMMay 26
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Hi Maria,

It sounds like using a HorizonCube might be the approach you're looking for. This creates a dense collection of horizons, each representing a paleosurface. You can then examine your data by either slicing through it using a 3D HorizonCube slider or by flattening the seismic data based on all the horizons within the HorizonCube. This flattened view is known as the Wheeler domain, where the vertical axis represents Relative Geologic Time. Consequently, time-slicing within the Wheeler domain allows you to analyze your data in terms of (relative) geologic time.

To generate a HorizonCube, the initial step involves mapping a framework of key horizons. This is typically done using one of OpendTect's inversion-based horizon trackers. These trackers are efficient, offer full user control, and can track multiple horizons concurrently by minimizing the discrepancy between the horizon dip and the seismic dip. After defining the framework horizons, the intervals between them are filled with a dense set of additional horizons. This infilling process can be guided by a model (e.g., proportional, parallel to upper, parallel to lower horizons) or driven by the data itself (inversion-based, or tracking the dip-field).

Please note that to utilize these functionalities, you will need licenses for OpendTect Pro, the Dip-Steering plugin, the HorizonCube plugin, and the SSIS plugin. The SSIS plugin is specifically required if you intend to analyze your data within the Wheeler domain.

You can find helpful training videos and webinars on our website that demonstrate these workflows. For instance, this training video illustrates how to track horizons using inversion-based algorithms.

I hope this explanation is helpful.

Best regards,

Paul
--
Paul de Groot
Special Adviser


-----------------------------------------------------------------------------------------------------------------------  
dGB Earth Sciences
Phone:+31 53 4315155
E-mail:paul.d...@dgbes.com
Internet:dgbes.com 
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