VP Geophysics Suite

Geologically-based forward modelling and inversion programs for potential field and time-domain electromagnetic data interpretation.

Programs include solutions for:

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VP Geophysics Suite  is a group of modelling programs designed for 3D modelling and inversion of gravity, gravity gradient, total magnetic field, magnetic gradient, and TEM data. It can be used stand-alone, integrated within GOCAD® Mining Suite, or used with Geoscience ANALYST. VP Geophysics Suite models are geologically based—they work directly with geological contact geometries as well as physical property distributions within geological units. This model parameterization lends itself to a variety of forward modelling and inversion applications.

The licence price depends on the selection of programs that best fits your individual needs. Academic pricing is available.

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”“[VPmg and GOCAD Mining Suite] allows the construction of plausible geological model for which concepts on single cross-section would not have been tenable.”

Mark DuffettSenior Geophysicist at Mineral Resources Tasmania

Geophysical modelling

VP algorithms discretize the 3D earth into tightly packed Vertical Prisms containing geological boundaries that separate individual packages of rock. Each model cell knows both its rock type and physical properties. This allows one to think in terms of geologic domains. The number of geological domains from prism to prism can vary allowing full 3D geological complexity. It can also perform unconstrained inversions.

Constraint types

  • Geometric weights near pierce points and fixed layers
  • Fixed properties at, and added weighting near to, drillholes (exert a radius of influence around the drillhole)
  • Select which lithologies are adjusted and which are fixed
  • Upper and lower property bounds per lithology

Unconstrained inversion

  • Conventional 3D property inversion
  • Apparent density/susceptibility/conductivity
  • 1D AEM
  • Geobody
  • Depth to basement

Parameterization

  • Versatile and compact
  • Supports a variety of model styles
  • Facilitates a variety of inversion styles
  • Local models can be incised into regional models
  • Topography explicitly incorporated into the model due to arbitrary cell thickness
  • Homogeneous or heterogeneous lithologic units
  • Each cell knows rock type and property allowing a variety of inversion options
  • Specific control over inversion
  • Inversion can operate directly on a geological model geometry by deforming 3D contacts

Forward modelling and inversion styles

VP forward modelling allows you to test your existing geological model against geophysical data for geological model evaluation and validation. The model parameterization supports a wide variety of model styles, which in turn facilitate a variety of inversion styles. Within a single model, domains can be homogeneous, have simple lateral variations, or full 3D heterogeneity. Susceptibility models may incorporate remanence and self-demagnetization.

Forward modelling features

  • Quantitatively test geological concepts
  • Validate geological models
  • Model remanence and/or self-demagnetization
  • Computes true TMI
  • Terrain correction
  • Cover correction
  • Regional modelling and incorporation of regional fields
  • Discrete domain modelling

Geometry inversion features

  • Geological data defines starting model
  • Depth to basement
  • Geobody inversion
  • Soft and hard constraints can be incorporated

Property inversion features

  • Homogeneous domain optimization
    • Bounded properties
    • Recover remanent magnetization direction
    • Invert TMG or magnetic amplitude data
  • Heterogeneous property inversion
    • Discretize domains internally
    • Invert for 3D property variations within domains
    • Solve for lateral property variations to recover apparent density or susceptibility
    • Discretize vertical cells to be constant or variable
    • Allows for conventional unconstrained inversion

Applications of VP models

VP models offer flexibility to support a wide variety of applications beyond simple unconstrained inversion.

Terrain and cover correction

  • Compute data from terrain models to generate the response and correct data
  • Apply response from layers of transported cover/regolith
  • Use density or density contrast values for gravity and gravity gradiometry data

Simple domain modelling

  • Test existing geologic models
  • Compute the response of simple or complex 3D wireframes and compare to measured data
  • Quickly run multiple simulations, varying depth extent, dip, and physical property

Depth to basement modelling

  • Invert for basement geometry for AEM, gravity, and magnetics
  • Guide the model with geological constraints or begin with a simple two-layer model
  • Ideal for greenfield projects
  • Allow for simplified lateral variation in the basement
  • Apply to any geological contact that exhibits a prominent rock property contrast (e.g. top of limestone, basalt dome modelling)
  • Output is a geological surface

Modelling magnetic remanence and self-demagnetization

  • Assign magnetic remanent parameters to geological domains
  • Invert for the bulk property remanent parameters: orientation and intensity (Q-ratio)
  • Utilize data that is weakly dependent on remanent magnetization: total magnetic gradient or magnetic amplitude
  • Modelling uses the true TMI
  • Invoke self-demagnetization in forward modelling and inversion that models the interactions between high-susceptibility cells

Geobody modelling

  • Derive a volume explaining the geophysical response
  • Initialize from depth estimation, prior information, or begin as a zero-thickness layer
  • Represent body as a geologic unit with its own property, bounds, and magnetization parameters

Regional modelling and edge effects

  • VP models live within an inclosing half space rather than a vacuum
  • Incise local models into regional models, explicitly taking the regional response into account
  • Minimizes edge effects
  • Regional models are VP models that can vary in complexity

Rotated models

  • Rotate models to assess the results directly in real world coordinates
  • Data rotation is performed internally and does not need to be done by the user
  • Optimize model mesh for surveys that have oblique layouts or line orientations

Potential fields and EM data

VPmg program: 3D modelling and inversion program for gravity, gravity gradient, TMI, and magnetic gradient data. Constraints include pierce points on drilled contacts and downhole measurements of physical properties. It generates geological models by assigning each cell to a geological unit. Geometry of contacts, as well as density or susceptibility of geological units can be adjusted via inversion. In each geological unit, the density or susceptibility can be homogeneous or heterogeneous. VPmg offers multiple ways of handling remanent magnetization through direct inversion of remanent magnetization parameters and inversion of derived data types.

Key features

  • Data reduction (e.g., gravity terrain correction, overburden stripping)
  • Depth to basement inversion
  • Rapid, accurate terrain modelling for gravity
  • Can embed a local model into a regional model to account for regional effects
  • Model and invert total-magnetic gradient or magnetic amplitude data
  • Modelling and inversion with self-demagnetization
  • Data options for gravity include: free-air or terrain-corrected data; ground, airborne or sub-surface gravity; gradiometry (any or all tensor components, plus FALCON Guv/Gne)
  • Data options for magnetics include: models true TMI; gradiometry (any or all tensor components, plus TMG); vector magnetics; magnetic amplitude; airborne, ground or sub-surface

Vpem1D program: 1D TEM inversion in a 3D geological framework, facilitating a variety of inversion styles. Optimal conductivities can be determined using homogeneous unit inversion when one or more geological units are considered uniform; heterogeneous unit inversion is applied when there are conductivity variations within units. Geometry inversion can be used to adjust interfacial depths (e.g., depth to basement).

Key features

  • Designed for inverting moving loop data from airborne central loop and Slingram configurations
  • Horizontal (along-line) or vertical B-field or dB/dt data can be inverted
  • During inversion, each vertical prism is treated as a layered model and the conductivity or geometry of active cells in the model is adjusted to reproduce the observed data
  • Each vertical prism is inverted in 1D within the context of the 3D VP model
  • Multi-moment transmitter systems can be inverted
  • Data options include: B-field and dB/dt, X, and Z; variety of slingram and moving loop systems

VPem3D program: Fast approximate 3D modelling and inversion program for airborne, ground, and  downhole TEM data. VPem3D has been designed for geologically-constrained inversion but is also suitable for unconstrained inversion. Geometry of contacts, as well as conductivity of geological units can be adjusted via inversion. In each geological unit, the conductivity can be homogeneous or heterogeneous.

Key features

  • VPem3D converts TEM decays to resistive limits in order to reduce run times by a factor of 10 or more relative to conventional programs
  • VPem3D can invert 3-component moving loop or fixed loop B-field or dB/dt data for virtually any configuration
  • Data options include: airborne, ground, and down hole EM time domain systems; X,Y, Z

VPutility program: Free program to help you create and modify VP models. It is compatible with all VP Geophysics Suite products. Adds constraints from drillhole pierce-points on contacts. Geological layers can be added simply with ASCII-based files. Creates heterogeneous cell models. Any VP model and its data can be written to a Geoscience ANALYST project file for visualizing and communicating in 3D.

Key features

  • Creates layered-earth VP models
  • Layers can be added to build subsurface modelling complexity
  • Exports VP models to Geoscience ANALYST
  • Information printout on an existing VP model
  • Download now
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Related resources

Software releases
November, 16 2018

VPmg, VPem1D and VPutility release

VP Geophysics Suite releases: VPmg version 9.2, VPem1D version 4.2 and VPutility version 1.1...
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Software releases
November, 28 2019

Geoscience ANALYST v3.0 release

This version introduces the long awaited Pro basic geophysics and Pro Geophysics - the next generation of fast, advanced geophysical tools...
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Q&As
April, 01 2019

Q&A Mineral Resources Tasmania

The construction of plausible geological models. 3D interpretation and modelling process is of a cyclical nature...
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Software tips
May, 01 2019

Coordinate Reference System re-projection

This GOCAD command, found in the Tools menu of upcoming v17u3, transforms atomic objects, drillholes, and grid
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Software tips
August, 10 2020

Importing and visualizing VP Geophysics models

In Geoscience ANALYST v3.1, VP Model objects can now be imported by a simple drag and drop! You can then visualize the model and,...
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Software tips
October, 19 2020

Viewing data from report items

In Geoscience INTEGRATOR table and chart items from ad-hoc or scheduled reports can be easily refreshed, using the same filters that were applied in the original report, to display current data.
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Software tips
February, 27 2020

Save classifications as xml

In GOCAD Mining Suite, Saving complex geological classifications, such as for drillholes, allows you to share them with a colleague or...
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Software tips
December, 09 2019

Simple unconstrained inversion

Computing an unconstrained inversion in Geoscience ANALYST Pro – it’s never been as easy!
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Software tips
June, 03 2019

Preview files in the Maps/plans/sections page

See the list of layers of your .dwg and .dxf files. Image sneak peeks are also available...
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Software tips
October, 05 2020

Linking cursors

In Geoscience ANALYST you can use the Link Cursors button to helps to track the location of your cursor across multiple Viewports...
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Software tips
March, 02 2019

2D map view

2D data can be viewed using the Panels menu > Add map view viewport. 3D data can be shown in the 2D view...
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Software tips
July, 01 2019

Imago drillhole imagery light table connection

In GOCAD, you can now connect to your Imago account by...
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