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Tips for intrusion modelling, and advanced surface editing in Leapfrog Geo.

During this technical workshop, we discuss advanced surface editing tips. Learn how to create accurate domains by developing a deeper understanding of intrusion parameters and the ways surfaces can be edited.




Ivan Naumenko
Project Geologist – Seequent


19 min

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Video Transcript

(upbeat music)

<v Ivan>Welcome to the technical</v>

Tuesdays webinars series.

My name is Ivan Naumenko

and I’m a Project Geologist with Seequent Australia.

Today’s webinar topic is advanced surface editing,

and we will focus on the intrusion surface type.

The Seequent solution encompasses

a range of software products applicable for use

across the money and value chain.

Today I’ll focus on Leapfrog Geo.

If you would like to find out more about other solutions,

please contact our support and sales stuff.

Today, I’ll focus on advanced surface editing techniques,

tips and tricks when using intrusion surface type.

We will we dig deeper into the settings menu

and we’ll review surface settings,

which you can adjust to achieve better results

when trying to make an intrusion surface to fit your data.

Also, we will discuss a couple of scenarios

that people are commonly facing

when modeling in Leapfrog Geo.

I will briefly go over the concept of intrusion surface type

and its main applications.

I will review the structure of intrusion surface,

In other words, how it’s generated and what it is based on.

We will look at trends editing the intrusion surface

by applying trends, linear or structural.

We will look at the intrusion values composite

in generation settings for intrusion surfaces

and see how these settings

can affect the result in surface.

Advanced surface settings, additional settings

that are available for intrusion surfaces and what they do.

Also we’ll have a brief look at the guide points.

What are those and how you can use guide points

to adjust your intrusion surface?

Before I jumped to the live demo

for the benefit of those who are new to LeapFrog Geo,

I would like to explain what the intrusion surface is.

Intrusion contact surfaces are rounder in shape

with an interior lithology that represents

the intrusion of lithology.

The intrusion removes existing lithologies and replaces them

with the intrusive lithology

on the youngest side of the contact surface.

Often the older side of the intrusion contact surface

is labeled as unknown, as typically intrusions displaced

multiple older lithologies.

Intrusion surfaces can be made from a range

of juicing different data types,

such as drilling polar lines,

GIS structural disks and points.

Now I’m going to switch to Leapfrog Geo

and continue with a live demo.

During this session,

we will focus on using the intrusion surfaces

in the construction of Geological Models.

Please keep in mind that intrusion surfaces

can be used to model porphyries, pegmatites or shells,

contamination in internal waste pockets,

as well as any other type of contact,

which generally requires a specific category of intervals

to be in close by contact and surface.

I have saved a couple of things to speed up the process

of switching between the views during this demo.

So let me quickly switch to the next scene.

First, let me start with an overview of the project.

This is a train in porphyry copper gold project

which has a number of drill holes intersecting

the various lithological units and a topographical surface

with some jazz data draped on it.

The units include a quartz vein, dollar ride dikes,

overburden unit, volcanic sediments,

granite diorite and quartz porphyry units.

The main focus of today’s session will be

on the last two units,

the granite diorite and the quartz porphyry.

For the benefit of those who are new

to Leapfrog Geo software,

I’ll briefly go through the process

of creating an intrusion surface.

I have already created a geological model

in which I am going to generate an intrusion surface.

Right click on the surface chronology object

in geological model.

Select the intrusion option

from the list of available objects.

If you would like to use your drill hole data

to create an intrusion surface,

then select new intrusion from basic lithology.

The first thing we need to do here,

is select the primary lith unit.

I will be building quartz porphyry intrusion,

so I will select quartz porphyry as a primary unit.

The next step is selecting the exterior and ignored units.

The contact in older lithologies

will stay under the exterior lithologies

and all younger ones will go into the ignored column.

As you can see, I have generated an intrusion surface

around quartz porphyry drill hole into walls.

If I have a closer look,

I can see that quartz porphyry contacts with the vein

and dike intervals have been ignored.

This is because I have set those lith units as younger.

Let’s have a closer look at the geological model

I have generated earlier.

As you can see, we have a sequence

of volcanic sediments model as a country rock unit.

We also have two intrusions,

the granite diorite and the porphyry,

all of these are caught by younger veins and dikes,

then clicked by the overburden unit at the top.

This surfaces have not been modified in any way

and are based purely on the drill hole data.

You might have already noticed a couple of issues

with the surfaces that need to be addressed.

Upon closer inspection we can see that,

there are problems with quartz porphyry intrusion surface.

Right in the center, there is a big gap split

in the quartz porphyry surface into parts,

as well as the small part of the surface disconnected

from the main body in depth.

These problems are likely to be caused by past drilling data

prompted to close off the intrusion surface rather

than generating a container surface.

Take into account a quite simple shape

of this porphyry intrusion.

my suggestion would be to avoid manual explicit edits

until we have tested different intrusion settings

to make the surface fit the data.

You will notice how the intrusion appears rounder,

as algorithm searches equally in all directions

to find correspondent intercepts.

My first thought would be to try using a linear trend

and see if applying direction of greatest continuity

will help to fix this problem.

To set the trend,

I’ll be using the tool called moving plane.

I will position the model in the scene so I can draw a plane

along this strike of the porphyry.

Please note that the moving plane doesn’t have to go

precisely through the center of the porphyry intrusion.

I will only use the plane to copy deep inasm values

to the intrusion surface.

Now I’m ready to apply the trend value

to my quartz porphyry intrusion surface.

Double click on the quartz porphyry intrusion,

and navigate to the trend tab in dialog window.

You can see that there is a set from plane button,

which allows you to copy the deep

as in with impeach information from the moving plane

to the intrusion surface.

The set to button allows you to copy the trend values

from other objects in your project,

or reset the trend back to isotropic.

You can control the strength of the trend

by adjusting the ellipsoid ratio values.

The ellipsoid ratio is determined that relative shape

and strength of the ellipsoids in the scene.

The maximum value is the relative strength in the direction

of the green line on the moving plane.

You can adjust it by left-clicking,

and activating controls on the moving plane.

The intermediate value is the relative strength

in the direction perpendicular to the green line

on the moving plane.

The minimum value is a relative strength

in the direction orthogonal to the plane.

As drilling is most often perpendicular to the orbital,

in the majority of cases, your minimum values,

should be your lowest number.

With the ellipsoid ratios, what is important,

is the ratio of the numbers you enter.

The higher the maximum and the intermediate numbers,

the stronger the trend is applied in that direction.

Things to consider when applying trends

are the geometry of the orbital,

as well as your drill holes pacing.

The thinner the intercepts

or the wider the drill holes are apart,

the stronger trend you may need to apply.

When applying a trend,

you may need to try a few different combinations of numbers

to create the optimal shape for your deposit.

I will click Concept From Plane and Okay

to apply the changes.

As you can see, the shape of the intrusion surface

has changed significantly,

and now it fits the data quite well.

Linear trends work very well on relatively simple deposits,

but quite often the structure and shape of the deposit

are much more complex and follow non-linear trends.

Leapfrog Geo has a tool called structural trend.

It allows you to apply a nonlinear trend

to an intrusion surface.

Structural trends create a flat ellipsoid anisotropy

that varies in direction with its inputs.

To create a new structural trend,

right click on the Structural Trends folder,

in the structural modelling folder

and select New Structural Trend.

The structural trend window will appear.

Structural trends can be created from surfaces

and from structural data.

Click add to select from the suitable inputs

available in the project.

I have generated a mash by creating a series of polar lines

representing the trend orientation and given locations.

And now I will use this mesh

as an input for my structural trend.

I won’t spend too much time explaining all settings

available for structural trends.

You can find more information about structural trends

in the help files or by contacting Leapfrog support team

in your region.

Now that I have my structural trend object ready,

I have to change some settings

in my quartz porphyry intrusion before I can apply

this structural trend to it.

I will double-click on the quartz porphyry intrusion object

to open the settings window,

then navigate to the surface in tab

and click on the additional options.

Then navigate to the interpolate tab,

I have to switch to the interpolate tab

from linear to spheroidal

before I can apply my structural trend.

You can read more about the interpolate settings

for intrusion surfaces in help files.

Now I can move back to the trend tab

and select the structural trend

that I would like to apply to this intrusion.

The outside value is a long range main value of the data,

such a new value of negative one for intrusions,

where the positive valleys are on the inside

and positive one for other surfaces

will result in a smoother surface in most cases.

Now we can see how the quartz porphyry intrusion

is following the structural trend.

We can compare it to the core support for intrusion surface,

with a linear trend applied to it.

Let’s dig a little bit deeper

and see how Leapfrog generates intrusion surfaces.

Leapfrog starts by extracting the intrusion intervals

from the drill hole database

and converting them into intrusion points.

Leapfrog converts the categoric interval data

into numeric point data.

We’ll now look closer at the point generation parameters.

I will double-click on the intrusion points,

the edit intrusion window will appear

displaying the point generation tap.

Here the surface and volume points are displayed

to show the effects of the surface offset distance

and background field space and parameters.

The surface offset distance parameters,

sets the top and bottom ends of the interval

and affects how surface behaves

when it approaches a contact point.

The smaller distance restricts the angles that an approach

and surface can take.

Another factor that affects the angles a surface will take,

is whether or not trend has been applied to the surface.

The background field space in parameter,

determines the approximate length of the segments

in the remaining intervals.

If the remaining interval is not a multiple

of the background field space and value,

Leapfrog will automatically adjust the spacing

to an appropriate value.

A smaller value for background field space

means high resolution

and therefore slightly smoother surfaces.

However, the computation can take longer.

Now let’s have a look at the intrusion points

composite in settings.

This can be accessed by double clicking

on the intrusion points and navigating to the composite tab

in the dialogue window.

Sometimes unit boundaries are poorly defined with fragments

of other lithologist within the lithology of the interest.

This can result in very small segments

near the edges of the lithology of interest.

Modelling defined detail is not always necessary,

And so compositing can be used to smooth these boundaries.

As you can see it Leapfrog applies automatic composition

into the input data.

This setting can be manually adjusted.

The automatic setting values depends

on the resolution settings applied to the surface

and set to half of the resolution value.

In this example the surface resolution is set to 30,

therefore the automatic compositing values are set to 15.

Might have already noticed that a short segment

in the center of the screen has been filtered out,

due to the compositing settings.

There are a couple of ways in which you can bring it back.

First, adjust the surface resolution value

to allow for shorter segments to be included.

Second, untick the simplify geology

by filtering short segments box.

And the third way is to adjust the filtering values,

so the short intervals of specific length

are included in the modeling.

Now I’ll try to untick the box,

simplify geology by filtering short segments,

then click Okay.

As you can see,

the short segments has now been included

in the construction of the intrusion surface.

There will be situations when dealing with photo models,

in which you might have limited data

in one or more of your fault blocks.

In such cases,

you may want to switch off the boundary filter

to allow Leapfrog, to use data outside of the domain

to inform the surface.

You can turn the screen

that the quartz porphyry intrusion surface

in one of the fault blocks

is based only on a single interval

and very much unconstrained at depth.

To rectify this issue, I will try

and adjust the boundary filter settings.

You can access the boundary filter settings,

by double clicking on the surface

and navigating to the surface and tap.

From the dropdown menu, under the boundary filter field,

select one of the settings you would like

to apply to this particular surface.

The boundary often intrusion

can be the geologic model boundary or fault block boundary.

The boundary filter setting determines how data used

to define the surface is filtered.

When it’s switched off, data is not filtered.

When it’s set to all data, all data is filtered.

When it’s set to drilling only, only drill hole data

and data objects derived from drill hole data are filtered.

When it’s set to custom, only the data objects

specified in the inputs tab are filtered.

I will switch the boundary filter off now

and see how this affects the shape

of the quart porphyry intrusion surface.

Now that Leapfrog uses the data outside the current boundary

set to the surface.

You can see that the shape

of the intrusion surface has changed significantly.

Turning off the boundary filter can also be beneficial

in situations where your intrusion

has post-dated your faulting.

The next parameter that I would like to talk about

is called value clipping.

To change settings for the intrusion surface,

double-click on the contact surface in the Project Tree.

The value clipping tab is only available

for intrusion contact surfaces,

clipping caps values that are outside of the wrench,

that by the lower bound and the upper bound values.

For example, if you change the upper bound from 16 to 10,

distance values above 10 will be regarded as 10.

The automatic clipping setting has different effects based

on whether a global trend or structure trend

is set in trend tab.

When the global trend is applied Leapfrog Geo

automatically clips values.

That is the automatic clipping setting is do clipping

and Leapfrog Geo sets a lower bound

and upper bound from the data.

To disable clipping untick Automatic Clipping,

then untick Do Clipping.

To change the lower bound and upper bound,

untick automatic clipping, then change the values.

When the structural trend is applied,

Leapfrog Geo automatically doesn’t clip the values.

To clip values untick Automatic Clipping,

then tick Do Clipping again, Leapfrog Geo sets

their law bound and the upper bound values from the data.

And you can change them if required.

In this case, I will apply a manual clipping

to demonstrate how you can control the shape

of your intrusion surface,

but just in the value clipping parameters,

I will clip the upper bound to 6, then click okay.

The top part of the mesh has changed quite significantly

because we have limited data to control

the shape of the intrusion near the surface,

Leapfrog pushes the intrusion out

creating so-called blowout.

Value clipping can be used

effectively to control some of the areas with blowouts.

In some situations you won’t be able to get away by simply

adjusting surface parameters,

and you’ll have to use some other input data

whether it’s a polyline, point, structure

or other type of data.

I will demonstrate briefly how you can edit

an intrusion surface with a polyline.

In this example,

I have a small quartz porphyry intrusion surface

in one of the fault blocks

and I’ll edit it using a polyline line.

Right click on the intrusion surface

and select edit with polyline.

Now I can start editing my surface.

In this instance, I will use points

rather than for other than polylines

to control the intrusion surface.

Once I have clicked Save Button,

the surface is being reprocessed and the points

are added to the intrusion.

The last topic that I’d like to cover in this webinar

is guide points.

Guide points can be created from any category of point data

in the project and edit to surfaces.

Category data that can be used to create guide points,

include downhole category point data, LAS points,

category data in on imported points, interval points.

Before I continue onto the guide points,

I’ll look great into our mid points from my blast hole data.

Guide points are good way of using blast hole data

to control surfaces.

Create the guide points

from the downhole interval midpoints,

then add the guide points to the surface.

Guide points are classified into interior and exterior,

and each guide point is assigned a distance value

that is a distance to the nearest point.

Guide points are classified to the interior and exterior

and each guide point is assigned the distance value

that is the distance to the nearest point

on the opposite side.

Interior valleys are positive

and exterior valleys are negative.

To create guide points, right click on the Points folder

and select New Guide Points.

A window will appear listing the category columns

available in the project.

Slide the categories to assign to interior,

the positive side and exterior the negative side.

You can also filter out distant values

by clicking the ignore distant values box

and entering a value.

Often distinct values have little effect on the surface

and filtering out these can improve processing time.

Click okay the guide points will appear

in the Project Tree under the points folder.

Now I’m going to add these guide points

to my quartz porphyry intrusion surface.

Right-click on the Intrusion Surface and select Add Points.

From the list of points I will select the Guide Points

and click Okay.

As you can see, the surface has now been updated

to include guide points data.

On this, I will conclude

the demonstration part of this webinar.

I hope you found it to be useful

and learn something new today.

The information from today’s webinar may allow you to review

your approach to editing of intrusion surfaces

in your modeling process.

If you have any inquiries regarding today’s presentation

or other topics,

please do not hesitate to contact your local support team.

You can see the contact details

for your local regional support teams on your screens now.

Please feel free to reach out to your local support team,

if you have further questions required for modeling support

or would like to discuss a remote training session.

Thank you very much for joining this webinar

and we hope to talk to you soon.