Geomodeller3D
Encyclopedia
Geomodeller3D is a methodology and associated software tool for 3D geologic modelling
developed by BRGM over the last 15 years. The software is written using Open CASCADE
in C++
for the engine (geometry, topology, viewers, data management, ...), Java
for the GUI
and data are stored in extensible mark-up language XML
. Geomodeller 3D has started to revolutionise the working practices, data standards and products of a geological survey
as a whole. The software takes into account all structural geology
data such as dip, dip directions, strike, hingelines and axialtrace to build the geometry of geological units.
data to enable the geologist to construct cross sections, or 3D models. 3D Geostatistical
interpolation (co-kriging) using all the data (location of interface, dip, direction, ...) produces a 3D implicit function
representing a solid model. The model build may take in account if necessary a network of geologic faults. The model could be represented by triangulated objects each corresponding to one of the geological units present. Geologists can draw the model in their sections to obtain a fence diagram. The geologist can use their knowledge to add information in the 3D space until he obtain a 'right' model.
profiles as well as gravity
and magnetic
data are often available. Interpreted seismic cross-sections directly provide data that can be processed directly as geometric constraints for 3D modelling. On the other hand gravity and magnetic data provide indirect constraints. Presently, a 3D geological model is considered as the initial state of a constrained inverse
modelling of this data. That inversion is based on an iterative method, which is applied to a discrete version of the domain under study. This inversion formulation allows separate inversion of either gravity or magnetic data or simultaneous inversion of both datasets and tensor
components of gravity and magnetic field
. The final result is a probabilistic 3D geological model.
Geologic modelling
Geologic modelling or Geomodelling is the applied science of creating computerized representations of portions of the Earth's crust based on geophysical and geological observations made on and below the Earth surface. A Geomodel is the numerical equivalent of a three-dimensional geological map...
developed by BRGM over the last 15 years. The software is written using Open CASCADE
Open CASCADE
Open CASCADE Technology is a software development platform for 3D CAD, CAM, CAE, etc. that is developed and supported by OPEN CASCADE SAS. It is available under the "Open CASCADE Technology Public License" which the developer claims to be . Despite this claim, it is not listed as compatible with...
in C++
C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
for the engine (geometry, topology, viewers, data management, ...), Java
Java (Sun)
Java refers to several computer software products and specifications from Sun Microsystems, a subsidiary of Oracle Corporation, that together provide a system for developing application software and deploying it in a cross-platform environment...
for the GUI
Gui
Gui or guee is a generic term to refer to grilled dishes in Korean cuisine. These most commonly have meat or fish as their primary ingredient, but may in some cases also comprise grilled vegetables or other vegetarian ingredients. The term derives from the verb, "gupda" in Korean, which literally...
and data are stored in extensible mark-up language XML
XML
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
. Geomodeller 3D has started to revolutionise the working practices, data standards and products of a geological survey
Geological survey
The term geological survey can be used to describe both the conduct of a survey for geological purposes and an institution holding geological information....
as a whole. The software takes into account all structural geology
Structural geology
Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover information about the history of deformation in the rocks, and...
data such as dip, dip directions, strike, hingelines and axialtrace to build the geometry of geological units.
A brief outline of the methodology
Geomodeller3D utilizes a Digital Terrain Model, surface geological linework, cross-sections, geophysical interpretation and downhole boreholeBorehole
A borehole is the generalized term for any narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water or other liquid or gases , as part of a geotechnical investigation, environmental site...
data to enable the geologist to construct cross sections, or 3D models. 3D Geostatistical
Geostatistics
Geostatistics is a branch of statistics focusing on spatial or spatiotemporal datasets. Developed originally to predict probability distributions of ore grades for mining operations, it is currently applied in diverse disciplines including petroleum geology, hydrogeology, hydrology, meteorology,...
interpolation (co-kriging) using all the data (location of interface, dip, direction, ...) produces a 3D implicit function
Implicit function
The implicit function theorem provides a link between implicit and explicit functions. It states that if the equation R = 0 satisfies some mild conditions on its partial derivatives, then one can in principle solve this equation for y, at least over some small interval...
representing a solid model. The model build may take in account if necessary a network of geologic faults. The model could be represented by triangulated objects each corresponding to one of the geological units present. Geologists can draw the model in their sections to obtain a fence diagram. The geologist can use their knowledge to add information in the 3D space until he obtain a 'right' model.
Inversion of the 3D model
In geological and mining or oil exploration applications, seismicSeismic wave
Seismic waves are waves of energy that travel through the earth, and are a result of an earthquake, explosion, or a volcano that imparts low-frequency acoustic energy. Many other natural and anthropogenic sources create low amplitude waves commonly referred to as ambient vibrations. Seismic waves...
profiles as well as gravity
Gravitation
Gravitation, or gravity, is a natural phenomenon by which physical bodies attract with a force proportional to their mass. Gravitation is most familiar as the agent that gives weight to objects with mass and causes them to fall to the ground when dropped...
and magnetic
Magnetism
Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...
data are often available. Interpreted seismic cross-sections directly provide data that can be processed directly as geometric constraints for 3D modelling. On the other hand gravity and magnetic data provide indirect constraints. Presently, a 3D geological model is considered as the initial state of a constrained inverse
Inverse problem
An inverse problem is a general framework that is used to convert observed measurements into information about a physical object or system that we are interested in...
modelling of this data. That inversion is based on an iterative method, which is applied to a discrete version of the domain under study. This inversion formulation allows separate inversion of either gravity or magnetic data or simultaneous inversion of both datasets and tensor
Tensor
Tensors are geometric objects that describe linear relations between vectors, scalars, and other tensors. Elementary examples include the dot product, the cross product, and linear maps. Vectors and scalars themselves are also tensors. A tensor can be represented as a multi-dimensional array of...
components of gravity and magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
. The final result is a probabilistic 3D geological model.