3D Grids - contains 3D grids

Right mouse button on the icon allows to:

• Create new grid
• Import from ECLIPSE
• Import GOCAD SGrid
• Import GOCAD TSolid
• Import GOCAD Voxet
• Import from RESQML EPC
• Export all to RESQML EPC
• Clear
• Slicer (Show slicer, Edit slicer parameters, Recalculate slicer parameters)
• Add folder

Grid types

When you choose Create new grid, g-Space first asks for a Grid type:

• S-Grid — a structured, corner-point grid of hexahedral cells built from the standard grid parameters (interpolation and grid steps, angle, length, zones and layers). This is the default grid used across most workflows; see 3D grid creating.
• Tetrahedral — an unstructured tetrahedral mesh generated from an existing structural model, so it honours the model's structural and stratigraphic framework. You select the source structural model and a Layering type, then set only the parameter that applies to it: Layers per zone for Proportional, or Layer thickness for Parallel to Top or Parallel to Bottom; the other field is greyed out and its value is ignored. For the full procedure, see 3D grid creating. Tetrahedral grids are suited to complex volumes that structured grids cannot represent.

Grids can also be brought in from external formats. Import from ECLIPSE and Import GOCAD SGrid load structured grids, while Import GOCAD TSolid and Import from RESQML EPC load tetrahedral grids.

Time and depth grids

Every 3D grid has a Time or Depth domain, set from the data it is built from: grids built from time horizons or time maps are time-domain, while grids built from depth horizons or depth maps, or imported grids, are depth-domain. No time-to-depth conversion is applied, so a time grid keeps its native time geometry. Grids from older projects that predate this option load as Depth.

In the Data Manager, the 3D Grids branch groups grids under two folders, Time and Depth, and each grid appears under the folder that matches its domain. A time-domain grid is displayed in the 3D view in time, and a depth-domain grid in the 3D view in depth.

Showing grid zones in the 3D view

Each zone under a grid's Zones folder in the Data Manager has its own checkbox. Select or clear a zone's checkbox to show or hide that zone in the 3D view, independently of the other zones. This works for both S-grids and tetrahedral grids that have zones.

A tetrahedral grid built from a faulted structural model is meshed one fault block at a time, so its cells follow the model's top and bottom surfaces and stay inside the fault blocks instead of crossing the fault. Where a zone is split into more than one block, each block appears as a separate item under that zone in the Data Manager, named after the zone's top and bottom horizons followed by the block number, for example <top horizon>/<bottom horizon> [Block 1]. Each block item has its own checkbox, so a single fault block can be shown or hidden in the 3D view. A zone that is not split by a fault keeps a single entry, with no block items below it.

Showing grids on the Location map

Every tetrahedral grid in the project is also drawn on the Location map. The grid's top surface is projected to plan view, so the map shows the triangulated top-surface mesh of the grid, including all blocks of a faulted grid, rather than a plain rectangular outline. A grid that has not been built yet is not drawn.

Each footprint is part of the Grid object of the Location map and is linked to that grid's own node under Data Manager > 3D Grids, so selecting or clearing the grid's checkbox shows or hides its footprint. The footprint takes the colour of the grid's first zone when that zone has one, and a neutral grey otherwise; like other Location map objects, its appearance is set in Visual Settings. The display also honours the Show tet grids option under Performance in Module properties, which is on by default.

For an S-grid, the Location map shows the lateral mesh of the current grid only.

Slicer

To cut the grids open in the 3D view, right-click 3D Grids in the Data Manager and choose Slicer > Show slicer. This switches on a single slicing plane in the 3D view. The first time you show the slicer from 3D Grids, g-Space fits the slicer box to the current 3D grid and opens the Slicer parameters wizard, where you can keep or change the box centre, start, steps, lengths and angle.

The plane cuts the grids that are currently shown in the 3D view along inline, crossline or depth. The part of the grid beyond the plane is clipped away and the exposed cut face is drawn as a real section of the grid: every cell is filled with its own value colour from the grid's current display settings, with no interpolation across a cell, and the cut face carries the same cell-boundary lines as the outer faces of the grid body. Drag the plane in the 3D view and the cut and its section face follow it immediately. The slicer works for both S-grids and tetrahedral grids.

Show slicer is a check item and is always available. Edit slicer parameters and Recalculate slicer parameters are enabled only while the slicer is shown: Recalculate slicer parameters fits the slicer box to the current 3D grid again and then opens the wizard, while Edit slicer parameters opens the wizard for the existing plane without refitting it. If no 3D grid is loaded, g-Space reports No 3D grids are loaded.

There is a single slicer plane, shared with the Geo-bodies and Structural models branches, so showing it from 3D Grids re-fits that same plane to the grids. For an introduction to the Slicer mode, see Geological modeling.

Editing grid cell values in the 3D view

Cell values of an S-grid can be corrected directly in the 3D view, for example to fix isolated cells after the grid has been built. Display the grid in a 3D view, then switch on the Grid cell edit control item in the view header toolbar. It is offered in both the time and the depth 3D view, and it edits the property the view is drawing, that is the current property of the grid, in any of its zones. Tetrahedral grids are not supported.

While the control item is switched on, select the cells to change:

• Left-click a cell to select it, and click it again to unselect it. Keeping the left button pressed and dragging over the grid adds every cell the cursor passes.
• Hold Ctrl and drag with the left button to draw a rectangle: every grid cell inside it is added to the selection, while Ctrl+Shift and drag removes the cells inside it. Only cells that are visible on the screen are taken, so cells hidden behind the grid body or behind another object are left out.
• Press Esc to clear the whole selection.

The selected cells are highlighted in the view. To change them, right-click in the view and choose Set value, a command that appears only while at least one cell is selected. The Set value dialog asks for a single Value; it is already filled in when all the selected cells hold the same value. Confirm the dialog and that value is written into every selected cell: the selection is cleared and the grid is redrawn immediately wherever it is displayed. The edited values belong to the grid property itself, so they are kept with the project.

Press Ctrl+Z in the same 3D view to undo the last Set value. Undo works only while Turn on undo is selected in Module properties.

Extract maps from a grid zone

To create a 2D map from a built grid zone, in the Data Manager expand 3D Grids > grid > Zones, right-click the zone and choose Extract Map. The Extract map wizard uses the selected grid and zone.

Under Map type, choose:

• Top of zone or Bottom of zone to extract a zone surface.
• For a depth grid, Isochore map or Isopach map; for a time grid, Isochron map.
• Property maps to create maps from properties that contain data in the selected zone. Select one or more Property entries and one or more Statistic values: Minimum, Maximum, RMS, Average, Median, or Most common for facies properties. A map is created for each compatible property-statistic pair.

The read-only Storage location shows the destination. Top and bottom surfaces are stored under Maps > Depth maps; the other results are stored under the corresponding Isochore maps, Isopach maps, Isochron maps or Property maps category.

The Output name prefix defaults to <grid>_<zone>, with spaces replaced by underscores. Result names append _Top, _Bottom, _Isochore, _Isopach, _Isochron, or the property and statistic names. Edit the prefix if required.

Click Run to create the maps, or Save to workflow to store the configured operation as a reusable workflow step. If the zone surfaces are unavailable, build the grid before running the extraction.

Extract Grid Property to LAS

This is the reverse of upscaling well logs into a grid. Right-click a single grid property (Data Manager > 3D Grids > grid > Properties > property) and choose Extract Grid Property to LAS to sample that property along well trajectories and store the result as a new LAS curve. It lets you compare the original log, the upscaled log and the modelled grid property along the same wells.

The Extract Grid Property to LAS wizard shows:

• Source grid and Source property — read-only, taken from the right-clicked property.
• Wells selection — All wells or Specific wells picked from the list.
• Output suffix — appended to the property name to form the curve name; it defaults to _from_<Grid>. For property Porosity on Grid1 the resulting curve is Porosity_from_Grid1.

The extraction follows the grid geometry and cell values, so no separate sampling step is required. A LAS curve is created for each processed well and stored under that well, ready to display in the Well log and Well correlation views. Wells that cannot be sampled, for example wells that lie outside the grid, are skipped; after the run a single summary message lists each skipped well together with the reason. If a well already has a curve with the target name, that curve is overwritten without confirmation, so change the Output suffix if you want to keep the earlier curve. Extraction is available for S-grids only; tetrahedral grids are not supported.