Veins

A vein is a type of contact surface that removes existing lithologies and replaces them with the vein lithology within the boundaries defined by hangingwall and footwall surfaces constructed from selected input data, a reference surface and a boundary. Creating veins from drilling data provides the most flexibility in refining the vein surface, but veins can also be created from points data, GIS vector data and polylines.

Modelling veins is an iterative process that may involve creating and refining a vein surface using different techniques before arriving at a surface that most accurately reflects sub-surfaces structures. Furthermore, the vein modelling tools available in Leapfrog Geothermal can be used for modelling other thin, planar geometries.

The way vein contact surfaces are organised in the project tree is intended to help you in working with the data available, so it is a good idea to have an understanding of this organisation so you can decide how to work with the different objects that contribute to the final vein surface. Veins are created and stored as part of a geological model’s Surface Chronology. Here, the hangingwall and footwall surfaces (with triangles shown) and points are displayed in the scene for a vein defined from drilling data. The reference surface (yellow) and the vein segments (red and blue cylinders) used to create the vein are also shown:

This vein () is made up of:

• Hangingwall and footwall surfaces (). When expanded, you can see the hangingwall and footwall data objects used to create the surfaces. In this example, the vein has been created from drilling contacts and so the hangingwall and footwall have been created from points ().
• Vein segments (), pinch out segments () and midpoints () extracted from drilling data. Veins created from data other than drilling data will not have vein segments, pinchout segments or midpoints.
  • Vein segments are categorised into hangingwall segments, footwall segments or excluded segments. Excluded segments are those that are completely enclosed within the vein lithology and so do not have hangingwall or footwall contact points.
  • Pinch outs are only included when the Pinch out option has been enabled.
  • Midpoints are used to create a first-pass reference surface.
• A reference surface () representing the trend or form of the vein. When a vein is created from drilling data, the initial reference surface is calculated as the best fit surface using the midpoints and the hangingwall and footwall surfaces. For veins created from data other than drilling data, the initial reference surface is a planar reference surface.
• A boundary object (). This is empty when the vein is first created.

If the vein is created from data other than drilling data, that data will be linked to from the hangingwall and footwall surfaces. For example, this vein was created from polylines. Note that there are no vein segments, pinchout segments or midpoints to work with.

Vein contact surfaces can also be created as part of a vein system (), in which case, each vein () is linked to the vein system via a “terminated vein” () that takes into account the vein’s relationship to other veins in the vein system. For example, in this vein system, a series of terminated veins make up the system. Expanding a terminated vein shows the vein surface () and any interactions with other veins in the vein system. Here vein 4501 interacts with vein 4400 on its hangingwall side, and so vein 4400’s hangingwall side is hyperlinked to vein 4501.

Vein 4409 interacts with two other veins, 4400 and 4501, and so contains hyperlinks to those veins:

Displaying the different objects that make up the vein can help you in making decisions on how to edit the vein. There are some settings specific to veins, such as the option for displaying different vein components by their hangingwall/footwall assignments:

The rest of this topic describes how to create and work with veins. It is divided into:

• Creating Veins
• Vein Surface Settings
• Pinch Outs
• Vein Segment Settings
• Editing Vein Segment Orientations
• Editing Vein Midpoints
• Editing the Reference Surface
• Editing the Vein Boundary
• Exporting and Importing Pinchout, Segment and Midpoint Edits

Creating Veins

Options for creating veins are:

• From the geological model's base lithology data. See New Vein From Base Lithology below.
• From other lithology contacts available in the project, including those from other drilling data sets. See New Vein From Other Contacts below.
• From GIS vector data, point data and polylines. See Veins From Other Data below.
• Creating a vein system. This results in a single lithology that represents all the veins in a model. Veins and their interactions are defined within the vein system. See Vein Systems.

New Vein From Base Lithology

To create a new vein from base lithology contacts, right-click on the Surface Chronology object and select New Vein > From Base Lithology. In the New Vein window, select the Vein lithology.

You can choose to use the query filtering already selected for the geological model by ticking the Inherit from GM box, or untick it and select from the available options in Query filter.

Click OK to create the vein, which will be added to the project tree as part of the Surface Chronology object.

New Vein From Other Contacts

When a vein is to be created using a lithology column other than the geological model’s base lithology column, right-click on the Surface Chronology object and select New Vein > From Other Contacts.

In the New Vein Contact window under Select Data, click the Select button and choose the column containing the needed lithology information.

Once a data column has been selected, the rest of the New Vein Contact window can be completed. Note that both the Vein lithology and Outside lithology fields draw their options from the geological model's Lithologies codes, not the codes from the column just selected. Selection of the lithology data to be used in construction of the vein happens in the next step. Here the Vein lithology field is asking which of the Lithologies in the geological model will be used to represent the data being introduced from the other contacts. If no code in Lithologies is appropriate, manually add a new code, as described in Model Lithologies.

If the vein contacts only one lithology, set the Outside lithology. Otherwise, leave Outside lithology set to Unknown.

After you click OK in the New Vein Contact window, the New Vein window will appear. The Vein lithology option in this window is used to specify the lithology code from the selected column that will be used to construct and model the vein. In this illustrated example, a geological model has been constructed from the Undistinguished column, and a new vein is being defined using other contacts contained in the Base_geology column. Therefore, the options showing in this Vein lithology are the codes from the Base_geology column, not the Undistinguished column nor the geological model's Lithologies.

The other fields in the New Vein window are as described in New Vein From Base Lithology.

Veins From Other Data

If suitable lithology data is not available, veins can be created from other data in the project, either GIS vector data, points or polylines. The steps for creating veins from other data are similar, regardless of the data used to create the surface:

• Right-click on the Surface Chronology, select New Vein, then select one of:
  • From Polylines
  • From GIS Vector Data
  • From Points
• Select the data objects for the Hangingwall and Footwall. These objects must already be in the project.
• Select the Vein lithology and the Outside lithology. The lithologies you can choose from are those defined for the geological model in the Lithologies object (see Model Lithologies).

Here, a points table is being used to create a vein:

Select data objects for both the Hangingwall and Footwall, then select lithologies. The Vein lithology and Outside lithology fields draw their options from the geological model's Lithologies codes.

• The Vein lithology field is asking which of the Lithologies in the geological model will be used to represent the data being introduced from the polylines, GIS data, or points. If no code in Lithologies is appropriate, manually add a new code, as described in Model Lithologies.
• If the vein contacts only one lithology, set the Outside lithology. Otherwise, leave Outside lithology set to Unknown.

Click OK to create the new vein. The new contact surface will appear in the project tree under the Surface Chronology. Expand the vein in the project tree to see how it was made.

Vein Surface Settings

Double-click on a vein in the project tree to edit its lithologies and various surfacing settings.

• The only settings you can change in the Lithologies tab are the Vein lithology and the Outside lithology.
• The options in the Surfacing tab are discussed below.
• The Inputs tab contains additional settings related to the boundary filtering and snap settings in the Surfacing tab.

Pinch Outs

Vein walls can be set to pinch out where drilling data indicates they do not occur. This is achieved by creating ‘outside’ intervals on wells that do not have an interior vein segment. These intervals are then flipped with respect to interior vein intervals, which, in effect means the footwall and hangingwall orientation has the opposite sense to the nearest interior intervals. This forces the hangingwall and footwall surfaces to cross, thereby pinching out.

The Pinch out option is disabled when a vein is first created. To enable it, double-click on the vein in the project tree and click on the Surfacing tab. Tick the box for Pinch out:

When the Pinchout on empty traces option is enabled, pinchouts will be created on well traces that have no logged data. To illustrate the effect of this setting, we have an artificial data set that has four traces with no logged data. When Pinchout on empty traces is disabled, the vein does not pinch out where it appears there are no actual vein segments:

When the option is enabled, however, the vein pinches out around the empty traces:

Click OK to process the changes.

For this vein, the surface occurs even where the vein lithology (green cylinders) does not occur and terminates at the boundary of the geological model:

When the vein is set to pinch out, it tapers out where the vein lithology does not occur:

You can change how much the vein pinches out by manually excluding some pinch out segments. To do this, right-click on the pinch out segments () in the project tree and select Edit in Scene:

You can also add the pinch out segments to the scene and click the Edit button () in the shape list:

The Vein Pinchout Segments will appear, along with a set of tools for selecting segments in the scene:

To select segments, click on the Select segments button () and click the Add segments button (). In the scene, draw a line across each segment you wish to select:

Selected segments are highlighted in the scene. If you accidentally select the wrong segment, either:

• Click the Remove segments tool () and draw across the point once again.
• Hold the Ctrl key while drawing across the point.

You can also:

• Select all visible segments by clicking on the Select all tool () or by pressing Ctrl+A.
• Clear all selected segments by clicking on the Clear selection tool () or by pressing Ctrl+Shift+A.
• Swap the selected segments for the unselected segments by clicking on the Invert selection tool () or by pressing Ctrl+I.

When you have selected at least one segment, click on the Assign to button, then select the category you want to assign the selected segments to:

The selected segments will be updated to reflect the change:

Click the Save button () to view the effect of the excluded pinch out segments on the vein. In this example, excluding the two segments results in the vein terminating at the boundary of the geological model:

Vein Segment Settings

When a vein has been created from contact points, you can change the vein segment settings by double-clicking on the vein segments object () in the project tree. This opens the Edit Vein window:

Settings in this window that change how contact points are generated from lithology data are:

• Include Wall Points/Midpoints at Ends of Holes
• Multiple Vein Intersections Per Hole

Include Wall Points/Midpoints at Ends of Holes

The Include wall points at the ends of holes setting determines whether or not hangingwall and footwall contact points are generated for segments at the ends of wells. If this setting is disabled, a contact point will not be created when a well ends in the vein lithology. The related setting, Include mid points at the ends of holes, determines whether or not midpoints are generated for segments at the ends of wells. Such midpoints could be distant from the centre of the vein structure and would, therefore, result in localised distortion of the reference plane.

You can see the effects of the Include wall points at the ends of holes setting here where the hangingwall (red) and footwall (blue) points are displayed alongside the vein lithology intervals (in yellow), the well traces and the resulting vein surface. In the first example, Include wall points at the ends of holes is disabled. Hangingwall points are not generated at the ends of the wells where indicated and so there isn’t enough data to build the vein surface:

In the second example, Include wall points at the ends of holes is enabled, hangingwall contact points are created and the vein surface that results is much more realistic.

Whether to enable or disable Include wall points at the ends of holes depends on your data. Consider disabling Include wall points at the ends of holes if:

• A vein is being prematurely truncated
• A vein is blowing out unrealistically

The Include mid points at the ends of holes affects how the midpoints are generated when vein lithology segments occur at the start or end of wells. When Include mid points at the ends of holes is disabled, the midpoints are still generated but are automatically excluded. In these examples, there are three segments where wells end with the vein lithology. On the left, Include mid points at the ends of holes is enabled and there are no excluded midpoints; all the midpoints are shown in green.

On the right, midpoints at the ends of holes are not included and so are shown in grey (Excluded).

Consider disabling the Include mid points at the ends of holes setting if your reference surface is “wiggly” or otherwise showing unexpected distortions.

To change the settings in this window for an existing vein, expand the vein in the project tree and double-click on the vein segments ():

Multiple Vein Intersections Per Hole

The Multiple vein intersections per hole setting is useful situations where wells might pass in and out of the same vein unit multiple times. Here a folded vein is shown with Multiple vein intersections per hole disabled (left) and enabled (right):

Editing Vein Segment Orientations

If you need to change the orientation of individual vein segments, e.g. for curved veins, you can do this by right-clicking on the vein segments object () in the project tree and selecting Edit In Scene.

If the vein segments object is already in the scene, you can edit it by clicking the Edit button () in the shape list:

Vein segments are categorised into hangingwall segments, footwall segments or excluded segments. Excluded segments are those that are completely enclosed within the vein lithology and so do not have hangingwall or footwall contact points.

The Vein Segments window will appear, along with a set of tools for selecting segments in the scene:

To select segments, click on the Select segments button () and click the Add segments button (). In the scene, draw a line across each segment you wish to select:

Selected segments are highlighted in the scene. If you accidentally select the wrong segment, either:

• Click the Remove segments tool () and draw across the point once again.
• Hold the Ctrl key while drawing across the point.

You can also:

• Select all visible segments by clicking on the Select all tool () or by pressing Ctrl+A.
• Clear all selected segments by clicking on the Clear selection tool () or by pressing Ctrl+Shift+A.
• Swap the selected segments for the unselected segments by clicking on the Invert selection tool () or by pressing Ctrl+I.

When you have selected at least one segment, click on the Assign to button, then select the category you want to assign the selected segments to:

The categories shown for vein segments are:

• Hanging Wall (auto), Foot Wall (auto) and Excluded (auto). These are the categories Leapfrog Geothermal assigned segments to when the vein was created.
• Hanging Wall (user), Foot Wall (user) and Excluded (user). Segments assigned to these categories have been manually assigned to these categories. These are the categories you can assign selected segments to.

Assigning a segment to the Auto category sets it to the category Leapfrog Geothermal automatically assigned it to when the vein was created, which has the effect of undoing any edits made previously.

The selected segments will be updated to reflect the change:

Click the Save button () to view the effect of the changes.

To revert to the categories assigned by Leapfrog Geothermal when the vein was created, select some segments and then assign them to the Auto category:

Editing Vein Midpoints

You can manually select vein midpoints and set them to excluded from processing. To do this, right-click on the vein midpoints object () in the project tree and selecting Edit In Scene.

If the vein midpoints object is already in the scene, you can edit it by clicking the Edit button () in the shape list:

The Vein Segment Midpoints window will appear, along with a set of tools for selecting midpoints in the scene:

The process is similar to editing vein segments, as described in Editing Vein Segment Orientations above. The categories shown for midpoints are:

• Midpoint (auto) and Excluded (auto). These are the categories Leapfrog Geothermal assigned midpoints to when the vein was created. If Include mid points at the ends of holes is disabled, some midpoints may be automatically categorised as Excluded (auto), which is the case for three of the midpoints shown above.
• Midpoint (user) and Excluded (user). Midpoints assigned to these categories have been manually assigned to these categories. These are the categories you can assign selected points to.

Assigning a midpoint to the Auto category sets it to the category Leapfrog Geothermal automatically assigned it to when the vein was created, which has the effect of undoing any edits made previously.

Editing the Reference Surface

A vein includes a reference surface () that represents the trend or form of the vein. When the vein is derived from drilling data, this is initially calculated as the best fit surface using the midpoints and the hangingwall and footwall surfaces. When derived from data other than drilling data, a planar reference surface is initially used. Whatever data source the vein is derived from, the reference surface setting can be changed to be a curved reference surface, a planar reference surface or another mesh in the project.

Double-click on the reference surface in the project tree; this opens the Edit Vein Reference Surface window and you can see what option is being used for the surface. In this example, the B1 vein has been created from lithology data and so it has a curved reference surface and the midpoints for the vein lithology are used as Input values:

Each option is described below:

• Curved Reference Surface
• Planar Reference Surface
• Custom Reference Surface

There is a great deal of flexibility in Leapfrog Geothermal for refining the reference surface, including the ability to created a surface in the Meshes folder from vein midpoints. A possible workflow is to:

1.  Create an initial vein in the geological model.

2.  Use the midpoints from this initial vein to create a mesh in the Meshes folder:

3.  Refine the mesh using the Meshes folder tools.

4.  Use the mesh as a custom reference surface.

Curved Reference Surface

The Curved reference surface option is the default for veins created from lithology data and the objects used to build the reference surface are shown in the Input values part of the Edit Vein Reference Surface window:

You can enable or disable the different data objects to see their effects on the vein by ticking and unticking the Active box, then clicking OK to reprocess the vein.

The Boundary filter setting for each object determines whether or not the data that lies outside the reference surface’s boundary is filtered.

• Tick Boundary filter so that the surface is only influenced by the data that falls inside the reference surface’s boundary.
• Untick Boundary filter if you want the surface to be influenced by the data both inside and outside the reference surface’s boundary.

The Curved reference surface option is the default for veins created from lithology data, whereas the Planar reference surface option is the default for veins created from other types of data. In order for a vein created from data other than lithology data to use a curved reference surface, other data must be added to it. To add data, right-click on the reference surface in the project tree and select Add or Edit.

Planar Reference Surface

Veins created from objects other than lithology data use a planar reference surface by default. To edit a planar reference surface, double-click on the reference surface in the project tree. This will open the Edit Vein Reference Surface window and display controls in the scene for adjusting the plane.

These handles work in the same manner as the moving plane controls, as described in The Moving Plane.

To use a planar reference surface for a vein created from lithology data, double-click on the reference surface to open the Edit Vein Reference Surface window, then select the Planar reference surface option. Adjust the plane in the scene, then click OK to reprocess the vein.

Custom Reference Surface

If you wish to use another surface in the project as a reference surface, double-click on the reference surface to open the Edit Vein Reference Surface window. Enable the Custom reference surface option, then select the mesh from those available in the project:

This option is useful if you wish to use an existing surface, such as the foot- or hanging-wall surface of an adjacent vein, as your vein’s custom reference surface, or if you need to use a fault surface to influence the trend of the vein. You can create and use your own custom vein surface, if needed.

Here, a thin folded layer has been modelled using a vein, created from a base lithology using sparse drilling data. The vein does not conform to known geology, crossing other modelled surfaces.

When the reference surface is edited to use a Custom reference surface with one of the existing surfaces in the model selected, the vein is modelled in a way that is more geologically reasonable:

Editing the Vein Boundary

When a vein is first created, its boundary () is empty:

Once a vein has been created, you can change its boundary by:

• Editing the Boundary with a Polyline
• Adding a Polyline to the Boundary
• Adjusting the Boundary Plane

Editing the Boundary with a Polyline

To edit the boundary using a polyline, right-click on it in the project tree and select Edit With Polyline. The current vein boundary will appear in the scene, together with drawing controls. Begin drawing the new boundary, as described in Drawing in the Scene, ensuring that the polyline drawn closes and does not intersect itself.

When you save the boundary, the vein will be updated to reflect the changes made. If you want to revert to the original boundary, right-click on the boundary object () and select Delete Polyline.

Adding a Polyline to the Boundary

You can also add an existing polyline to the vein boundary. To do this, right-click on the vein’s boundary in the project tree and select Add Polyline. In the window that appears, select the polyline you wish to use:

If you have edited a vein’s boundary with a polyline, you can use that polyline for other vein boundaries. To do this, right-click on the vein that has been edited and share the polyline; a copy will be saved to the Polylines folder which will be linked to from the vein. You can then use the polyline for other vein boundaries using the Add Polyline option.

Adjusting the Boundary Plane

Another option for editing a vein boundary is to adjust the boundary plane. To do this, right-click on the boundary in the project tree and select Adjust Plane. The plane will be displayed in the scene, along with the Adjust Boundary Plane window. You can use the handles on the plane to adjust its position or you can enter the information in the Adjust Boundary Plane window.

Click OK to apply the changes to the vein.

To revert to the original boundary plane, right-click on the boundary object and select Adjust Plane. In the Adjust Boundary Plane window, click on the Set to Default button and click OK.

Exporting and Importing Pinchout, Segment and Midpoint Edits

If you have made edits to vein pinchouts, segments, midpoints, you can export them for use in other veins and models in the current project or in other projects. The edits are exported in a text file.

To export vein edits, right-click on the vein in the project tree and select Export Vein Edits:

If the vein has no manual edits, a message will be displayed saying so. Otherwise, you will be prompted to save the file on your local hard drive.

To import vein edits, right-click on a vein and select Import Vein Edits. Select the file you wish to use, then click Open. The edits in the file will be applied to the vein. If there are edits in the file that don’t match the vein, a message will be displayed and a text file listing the errors will be saved on your local hard drive.

 

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