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. Options for editing veins in Leapfrog Geothermal are complex, so it is good to have an understanding of how veins are organised in the project.

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 lithology 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 lithology contacts and so the hangingwall and footwall have been created from points ().
  • Vein segments and pinch out segments () extracted from drilling data.
    • 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 a vein is created from lithology contacts and the Pinch out option has been enabled.
  • A reference surface (). This is calculated as the best fit surface using the hangingwall and footwall surfaces. The reference surface can be curved or planar or another surface in the project can be used.
  • A boundary object (). This is empty when the vein is first created.

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:

You can add data such as points, GIS vector data and polylines to the hangingwall and footwall surfaces and the reference surface. You can also edit these surfaces with polylines.

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

For a general introduction to how veins interact with other contact surfaces, see Vein Contact Surfaces in the Contact Surfaces topic.

Creating Veins

Options for creating veins are:

  • From lithology data, using the base lithology used to define the geological model or other contacts available in the project, including those from other drilling data sets. See Veins From Lithology 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.
Veins From Lithology Contacts

To create a new vein from lithology contacts, right-click on the Surface Chronology object and select either New Vein > From Base Lithology or New Vein > From Other Contacts. The only difference in the two methods is that when creating a vein from other contacts, you must first select the lithology column from those available in the project and specify the Vein lithology and Outside lithology.

In the New Vein window, select the Vein lithology:

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

The Include points at the ends of holes and Multiple vein intersections per hole settings are discussed later in this topic, in Editing Vein Segments. 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 ():

Veins From Other Data

If suitable lithology data is not available, veins can be created from other data in the project, such as GIS data, points and 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 and select one of the data types from the New Vein menu.
  • 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, points data is being used to create a vein:

Select points data objects for both the Hangingwall and Footwall, then 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.

Editing Veins

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.
Boundary Filtering

When data objects are added to a surface, there are two ways to handle the data that lies outside the surface’s boundary:

  • Filter the data. The surface is only influenced by the data that falls inside the surface’s boundary.
  • Leave the data unfiltered. The surface is influenced by the data both inside and outside the surface’s boundary.

The boundary of a vein can be the geological model boundary or a fault block boundary.

The Boundary filter setting determines how data used to define the surface is filtered:

  • Off. Data is not filtered.
  • All data. All data is filtered.
  • Drilling only. Only drilling data and data objects derived from drilling data are filtered.
  • Custom. Only the data objects specified in the Inputs tab are filtered.

The Filter segments by boundary setting in the Inputs tab is enabled by default when the Boundary filter setting in the Surfacing tab is All data or Drilling only. When Filter segments by boundary is enabled, the vein surface will only be influenced by the segments that falls inside the vein boundary.

Snapping to Data

Often, surfaces should honour drilling data and treat data objects such as polylines and GIS data as interpretations, as discussed in Honouring Surface Contacts.

There is a Snap to data setting for a geological model as a whole that is set in the Geological Model > General tab (see Editing a Geological Model). Snap to data can also be set on a surface-by-surface basis by double-clicking on the surface in the project tree and then clicking on the Surfacing tab.

For individual contact surfaces, the options are:

  • Inherit from GM. The setting for the geological model as a whole is used. This is the default setting.
  • Off. Surfaces do not snap to the data used to create them.
  • All data. Surfaces snap to all data within the Maximum snap distance, which includes drilling data and any data added to the surfaces.
  • Drilling only. Surfaces snap to drilling data and data objects derived from drilling data within the Maximum snap distance but not to other data used to modify the surfaces.
  • Custom. Surfaces snap to the data objects indicated in the Inputs tab for each surface.

Take care in enabling snapping and in selecting what data the surface will snap to, as the more data you include, e.g. by setting a large Maximum snap distance or selecting All data for Snap to data, the greater the possibility that errors in the data or assumptions inherent in interpretations (e.g. polylines) will cause distortions in the meshes. If you do enable snapping, it is best to snap only to drilling data. See Honouring Surface Contacts for more information on these settings.

If you need a surface to honour drilling data but treat other data objects as interpretations, select Drilling only. To honour some data objects while treating others as interpretations, select Custom, then click on the Inputs tab to enable snapping for individual objects.

Surface Resolution

See Surface Resolution for a Geological Model for information about the surface resolution settings for veins.

Adaptive surfacing for veins is new in Leapfrog Geothermal 2021.1. When existing geological models with veins are upgraded in Leapfrog Geothermal 2021.1, the Adaptive setting will be disabled. If the vein is set to inherit its resolution from the geological model and the geological model has been set to use adaptive resolution, the Inherit resolution from GM setting will be disabled so that the vein’s previous settings are preserved.

Vein Thickness

Veins have two thickness settings that force the vein to maintain a minimum or maximum thickness. If footwall and hangingwall points are in pairs, it is not usually necessary to set the Minimum thickness or Maximum thickness.

  • If the vein intersects itself, set the Minimum thickness to a value that is less than the minimum distance between any two contact points.
  • If the vein widens out toward the edges of the geological model set the Maximum thickness to a value that limits the effects of long segments.

If the Pinch out option is enabled, you will not be able to set the Minimum thickness.

If you set the Maximum thickness and Pinch out, the Pinch out setting is applied before the Maximum thickness.

Note that if Snap to data is enabled, snapping occurs after the vein thickness has been calculated. If it appears that the vein surface is not honouring the thickness setting, check what data the surface is snapping to.

Vein 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. Click OK to process the changes. The vein will be updated and pinch out points () will be added to the vein in the project tree.

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 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:

Note that the segments displayed in the scene below are the pinch out segments rather than the well segments shown in earlier scenes. The grey segments are excluded and the currently selected segment is highlighted in the scene.

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.

To change the width of the line used to select segments, click on the Change line width button () and enter a new value. You can keep the Set Line Width window open while you select intervals so you can change the line width as required:

Note that the current line width is indicated by the Change line width button.

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:

Editing Vein Segments

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:

There are two settings in this window that change how contact points are generated from lithology data. These are discussed below. See:

You can also manually edit vein segments to change whether they are hangingwall segments, footwall segments or excluded segments. See Editing Vein Segment Orientations.

Include Points at Ends of Holes

The Include points at the ends of holes setting determines whether or not hangingwall and footwall contact points are generated 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.

You can see the effects of this 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 points at the ends of holes is disabled. Hangingwall points are not generated at the end of the wells on the right and so there isn’t enough data to build the vein surface:

In the second example, Include 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 points at the ends of holes depends on your data. Consider disabling Include points at the ends of holes if:

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

To change the setting 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):

Note that you may also need to edit the vein’s reference surface and the vein segments to achieve a realistic surface. See The Vein Reference Surface and Editing Vein Segment Orientations below.

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.

To change the width of the line used to select segments, click on the Change line width button () and enter a new value. You can keep the Set Line Width window open while you select intervals so you can change the line width as required:

Note that the current line width is indicated by the Change line width button.

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.

You can change the colours if you wish, but note that when the segments are displayed in the scene, the default colours make it easy to differentiate between automatically-categorised segments and those that have been edited.

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:

The Vein Reference Surface

A vein includes a reference surface () that is the best fit for the objects that make up the hangingwall and footwall surfaces.

A vein can have a curved reference surface, a planar reference surface or it can use 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

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.

Boundary filtering for the midpoints used to create a curved reference is controlled by the setting for the vein itself. See Boundary Filtering earlier in this topic for more information.

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.

Using the Add option, you can add points data, GIS data or polylines to the surface. Using the Edit option, you can add a polyline to the reference surface, but its editing options are limited in that you can not add tangents or normals to the polyline.

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 a mesh in the project as, for example, a common reference surface for all veins in a geological model. To do this, edit the reference surface for each vein so they all use the common surface for the Custom reference surface option:

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 adding a polyline an adjusting the boundary plane.

To edit the boundary using a polyline, right-click on it in the project tree and select Edit. 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.

The other option 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.

 

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