Dear colleagues, dear sponsors,

Welcome to Nancy for the 2010 Gocad Meeting! This year has been very active in the Gocad Research group, and we are very pleased to present our recent advances for better data and knowledge integration in geomodeling.

For the last few years, geological modeling has been revolutionized by the modeling of geological surfaces as interfaces between volumes rather than free-form surfaces embedded in a 3D space. This principle, made possible by increased computer memory, leads to new ways of building accurate subsurface models to integrate more geological concepts. Along these lines, Cécile Massiot obtained new results to integrate constraints derived from cleavage and axial direction analyses in 3D structural modeling. Also, the robustness of the implicit structural modeling method is an element which led Nicolas Cherpeau to propose a new approach to manage large structural uncertainties. In his paper, Nicolas generates stochastic fault networks from sparse fault interpretations and geological rules, which allows not only to represent small geometric uncertainties about a reference model, but also to significantly alter the fault network connectivity to reflect the lack of data or the ambiguity of seismic interpretation. To assess the impact of such uncertainties on the modeling output, it will be useful to “orient” the generation of these models using ancillary data such as production curves, well tests or other geophysical data. One element toward that goal is presented this year by Jean-Jacques Royer, who proposes a theoretical framework to progressively reshape geological surfaces for assimilating potential field data.

A significant part of structural framework uncertainty also originates in the stratigraphic correlations. To address this issue, Florent Lallier proposes a stochastic well correlation method and presents improvements to deal with multiple wells and new elementary rules to be used with this algorithm. This research is currently applied to carbonate environments, but the proposed framework is very general and could be applied in other depositional environments.

Another active research topic this year has concerned the modeling of post-depositional heterogeneities such as karsts and fractures. In his paper, Francois Bonneau investigates several new strategies to simulate branching karst networks while controlling the connectivity of the cave system. Because the input of such a simulation must be constrained by data, Rémi Vigouroux proposes several statistics to characterize the karst geometry and topology on known systems, to be used in the simulation later on. On the fracture modeling side, Vincent Henrion has pursued his work on fracture growth modeling to reproduce realistic geometry and connectivity of discrete fracture networks from fracture density maps and orientations derived from seismic characterization or 3D deformation analyses.

Among the various strategies to assess rock deformation, we believe that 3D geomechanical restoration is a method of choice. This year, Pauline Durand-Riard has been improving the restoration code by adding new boundary conditions, accounting for transverse isotropic material (with the help of Marc-Olivier Titeux), and she is proposing guidelines to set restoration parameters appropriately. She also applied restoration coupled with decompaction on the Annot sub-basin (SE France) to help characterize its tectono-sedimentary evolution. Among the various applications of 3D restoration, Gautier Laurent is also looking at how it can be used to build an accurate chronostratigraphic parameterization to be used for petrophysical modeling.

Restoration is one of the many geomodeling problems which calls for appropriate visualization methods. Although no paper is strictly devoted to this, visual clipping of unconformable stratigraphic sequences and 3D strain tensor visualization is now available in gocad research plugins. Also, Thomas Viard worked this year on the volume visualization of structural uncertainty (see cover) and on the visualization of uncertain time-varying fields as generated by flow simulation on several static and hydrodynamic models. Last but not least, Grégoire Piquet proposes an interesting particle-based method to visualize vector fields in 3D.

I started this introduction by mentioning the recent revolution in volumetric geological modeling. Another revolution is under way in the field of numerical geometry, thanks in particular to the Work of the Alice Team led by Bruno Lévy at INRIA Lorraine. We are very excited that the collaboration between the Gocad Research Group and Alice is stronger than ever, and leads to several contributions in these proceedings. The first one, by Jeanne Pellerin, concerns the coupling of Gocad and the Graphite application developed by the Alice team. Athough very technical, this work offers new possibilities in terms of processing and visualization of objects in Gocad, strengthens the connection between our groups, and has the ambition to accelerate the use of cutting edge geometry processing methods in geomodeling applications. The work of Romain Merland is a perfect illustration of this: Romain has been looking at the longstanding problem of reservoir grid generation honoring both static features and gridding constraints. His first results exploiting Centroidal Voronoi Tesselation (see also Bruno Lévy’s paper) can account for anisotropy fields and adaptive density while strictly honoring classical two-point flux discretization constraints.

This volume contains other contributions from Gocad Research Group researchers and Gocad Sponsors on new geosciences data interpretation and processing methods, geostatistical modeling, and applications of geomodeling to petroleum, mining, environmental and geodynamic problems. I would like to thank all the authors of this volume for their hard work and for sharing their work with the community, and I wish wish you an enjoyable and rich Gocad Meeting!