Mise en cohérence automatique d'un modèle géologique 3D légèrement perturbé

Olivier Grosse. ( 2002 )
INPL

Abstract

3D modeling is a precious tool for the oil geologist. It helps him for instance to understand the geological structures of the subsoil and to monitor the exploitation of an oil field. A 3D earth model is a partition of the 3D space by a set of surfaces into closed domains called regions. These surfaces correspond to geological features such as the horizons and the faults that have been detected by means of drillings or geophysical methods. A geologic model is not a rigid representation of the subsoil: it is brought to evolve during its existence to take into account new data and the various interpretations of the geologists. Editing a 3D earth model while keeping its consistency implies to respect several constraints on the surfaces that delimit the model regions: these surfaces should not intersect each other except on their borders and should be contiguous. Here, we propose a new type of model in the aim of simplifying the editing operations. In this model, each surface is subdivided into domains by a set of lines defined by the relations connecting the surfaces with their environment. So, operations such as cutting up the surfaces and deletion of scars are not necessary any more when the model is modified. For that purpose, we extend the concept of Hierarchical Generalized Maps to represent the three levels of subdivision needed for the complete description of such a model: • the partition of the 3D space by the surfaces into regions; • the subdivision of every surface by a set of lines into 2D domains; • the triangulation of surfaces. It is not always necessary to modify the topology of a model. Thus, we propose a method deriving from the Free Form Deformation tools, which consists in continuously deforming the geological models. Given for some points their new position, we can define a mapping function to compute the displacement of the remaining points of the model. We have chosen the DSI interpolator to estimate this function. The flexibility of this method

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BibTeX Reference

@PHDTHESIS{Grosse02MCA,
    author = { Grosse, Olivier },
     title = { Mise en cohérence automatique d'un modèle géologique 3D légèrement perturbé },
   chapter = { 0 },
      year = { 2002 },
    school = { INPL },
  abstract = { 3D modeling is a precious tool for the oil geologist. It helps him for instance to understand
the geological structures of the subsoil and to monitor the exploitation of an oil
field. A 3D earth model is a partition of the 3D space by a set of surfaces into closed
domains called regions. These surfaces correspond to geological features such as the
horizons and the faults that have been detected by means of drillings or geophysical
methods. A geologic model is not a rigid representation of the subsoil: it is brought to
evolve during its existence to take into account new data and the various interpretations
of the geologists.
Editing a 3D earth model while keeping its consistency implies to respect several
constraints on the surfaces that delimit the model regions: these surfaces should not
intersect each other except on their borders and should be contiguous. Here, we propose
a new type of model in the aim of simplifying the editing operations. In this
model, each surface is subdivided into domains by a set of lines defined by the relations
connecting the surfaces with their environment. So, operations such as cutting
up the surfaces and deletion of scars are not necessary any more when the model is
modified. For that purpose, we extend the concept of Hierarchical Generalized Maps
to represent the three levels of subdivision needed for the complete description of such
a model:
• the partition of the 3D space by the surfaces into regions;
• the subdivision of every surface by a set of lines into 2D domains;
• the triangulation of surfaces.
It is not always necessary to modify the topology of a model. Thus, we propose
a method deriving from the Free Form Deformation tools, which consists in continuously
deforming the geological models. Given for some points their new position,
we can define a mapping function to compute the displacement of the remaining points
of the model. We have chosen the DSI interpolator to estimate this function. The
flexibility of this method }
}