3-D Model Building and Geomechanically-Based Volume Restoration: The Next Generation Tool

Lepage, François¹, Thomas Laverne¹, Frantz Maerten¹, David Desmarest¹, Emmanuel Quetelard¹, Michael Palomas¹, Laurent Maerten¹ (1) IGEOSS, Montpellier Cedex2, France

For many years structural geologists have been using computer tools to construct balanced 2D and 3D structural models. The tools available to restore geological structures are based on a variety of geometric techniques, which aim at reproducing natural deformation, constrained by assumptions such as preservation of area or volume, minimization of deformation, minimization of changes in segment length. While the challenge of restoring structural models could be attributed to inadequate data, hardware, and software in the past, the challenge today is to integrate a complete mechanics into the methodology. Indeed, it is established that rock deformation is a physical process that involves parameters such as the initial geometry, the distribution of mass, rock properties, and the constitutive laws that govern the deformation. Therefore, we propose the next generation tool that allows elastically-based 3-D volume restoration. The method, when realistically well constrained, honors the fundamental physical laws that govern deformation, that are (i) conservation of mass, (ii) conservation of momentum and (iii) conservation of energy. Mechanically-based decompaction as been implemented based on both the heterogeneous rock properties assigned to the model and the compaction rule chosen. This innovation permits fault slip during decompaction and does not unrealistically deform the model. We describe the complete workflow from interpreted horizons and faults, to 3-D model building, to model setup, to volume restoration. We offer examples to illustrate the applications in the oil and gas industry for the characterization of structurally complex reservoirs.