Nevertheless, the user can manage unconformities with polarity changes by disabling the "polarity consistency" option in the Properties of the model grid
The preview is done using a couple of constraints around the yellow seed, meanwhile the real geomodel uses all the constraints present in the entire grid.
III. What is the difference between horizons coming from the model grid and horizons coming from the horizon stack?
The horizons coming from the Horizon Stack are modelled through the Geomodel, meaning they are smoother, covering the entire survey, even in case of erosion or non-deposition, and following the trend of the seismic They are not seismic consistent anymore.
No, it doesn’t. Even if there is a gap in the marked horizons, by increasing the interpolation parameter in the geomodel computation, PaleoScan will fill the gaps and the horizon stack will be complete (if the interpolation size is high enough).
Yes. To rename a horizon from the grid, the user has to open the horizon list, right click on the name and select the option "rename".
The horizon can also be selected (F keyboard shortcut) by double clicking on the horizon (the horizon turns red) and then it can be named from the properties.
Having gaps in the preview doesn't mean having a lack of nodes, it just means that the nodes inside the gaps are not linked to the rest of the geomodel. To address this issue, the user needs to connect nodes inside the gaps to nodes outside the gaps (i.e. where there is a preview).
If there is a gap in the preview that the user cannot fill, increasing the interpolation parameter can fill the gap in order for the geomodel to be complete.
To refine the grid, the user needs to be in cross navigation mouse mode (G shortcut). He then needs to place the seed on a specific event and press W to first activate the chosen event. Next, he has to place the yellow seed on the belonging event and press W again, PaleoScan will connect both horizon patches. This action can be repeated as many times a needed to build the current horizon to its desired size.
Once the user is done with the horizon refinement, he can click on the space bar to validate or M to mark the event.
Yes. To achieve this, the user needs to open the model-grid and click on the "Model-grid constraint" icon and then follow the workflow.
Make sure to start from the Initial Grid (and not the AutoInterp), thus, the constraint from the horizons will be applied to a "blank canvas", and there will not be any conflict.
Add the horizons as constraints to the Initial Grid using “Horizon Constraint”.
Re-run an auto-interpretation using "Automatic Propagation". That will take into account the horizon constraints.
To save or extract a specific horizon, the user needs to mark the horizon, then select it (using F shortcut for selection mode) and click on the blue floppy disk or do CTRL+S
The grid can be bounded between two horizons, or from the top/bottom of the seismic to the key horizon. The option is in the “Advanced Options” of the Model-Grid creation tool.
The input horizons need to be composed of continuous time maps where the Model-Grid has to be generated: no node will be computed between a hole (=void) and a time map, or a hole (=void) and another hole (=void). The Propagate/Interpolate tool from Horizon Editing tool bar can be used to fill existing gaps or to generate a full Time Map from a picked horizon.
In order to properly interpret then model the stratigraphic level of interest, it is strongly advised to shift both the upper (-100/300 ms) and lower (+100/300 ms) boundaries. This preliminary data conditioning simply uses the Vertical Shift tool from Horizon Editing tool bar.
A cropped seismic volume can also be created. Using the volume module, the user can create an extraction area and then extract this sub volume from the original one.
Yes, to re-edit a marked horizon, the user needs to activate the cross-navigation mouse mode (G shortcut), put the seed on the marked horizon and press W.
In the "Advanced Options" of the Model-Grid creation tool, a "no signal area" parameter allows the user to drop objects (layers, geobodies and Multi-Z) so that PaleoScan will not create nodes inside those objects.
XIV. When I display the model grid nodes on a section, the nodes are not always located on a seismic event, why is that?
The nodes display is a projection when the seismic section is not located exactly at the center of the patch. Therefore, the nodes might be slightly shifted compared to the seismic event. The patches, which define the horizons, will follow the seismic events anyway.
The user needs to click on the “Update” button at the bottom of the horizon list to refresh it. The marked horizons will appearlike below, with a M:
If faults and/or no signal areas were used for the model grid generation, there will be voids at the location of the faults/no signal areas. This is quite useful if the user does not want to generate the grid around salt domes for instance. If the user wants to have nodes at these locations, he must not use the faults/no signal area option.
A marked horizon is a horizon you decide to highlight (using M to validate it) by displaying it in color, it is not a saved horizon.
Horizons that you do not marked are also taken into account and validated by pushing the Space bar.
All horizons, marked and unmarked, will be used to calculate the Geomodel.
That also means you have to save the global interpretation using the top bar of your model grid window.