New gOcad® developments in the field of 3-dimensional structural geophysics

Laurent Aillères

For decades, geologists have tried to share 3-dimensional interpretations using 2-dimensional images (map, cross-sections,...). Use of block diagrams is also common but they are only made of three 2-dimensional slices, usually one horizontal and two vertical slices, but a full description of the volume is still missing. Block diagrams can even lead to misinterpretation since geologists tend to assume cylindrical structures to mentally relate structure traces on maps and cross-sections. In hard-rock geology, full 3-dimensional information (such as 3D seismic in the petroleum industry) is usually unavailable or spatially scarce. The starting point to any 3-dimensional modelling is very often a set of cross-sections and/or a set of points associated with information such as geological measurements (foliations, lineations, thickness of a unit, etc...). For the past century, geologists have been collecting such data. Using all available information still remains a big task since different kinds of data from different sources will not be consistent once put in a 3-dimensional space. Consequently, building 3-dimensional models involves a great deal of re-interpretation of the data. As such this is a great way to validate or refine previous interpretations which are often based on 2-dimensional representations and assuming consistency in the third dimension.

This paper deals with and advertises new developments implemented within the gOcad® software to enable the development of 3-dimensional structural geophysics models.