3D Restoration of sedimentary terrains: The GeoChron Approach

Abstract

Three-dimensional restoration of complex structural models has become a recognized validation method. Bringing a sedimentary structural model back in time to various deposition stages may also help understand the geological history of a study area and follow the evolution of potential hydrocarbon source rocks, reservoirs and closures. Most current restoration methods rely on finite-element codes which require a mesh that conforms to both horizons and faults, a difficult object to generate in complex structural settings. Some innovative approaches use implicit horizon representations to circumvent meshing requirements. In all cases, finite-element restoration codes depend on elasticity theory which relies on mechanical parameters to characterize rock behavior during the physical unfolding process. In this paper, we present a geometric restoration method based on the mathematical theory provided by the GeoChron framework. No assumption is made on the extent of deformation, nor on the nature of terrains being restored. Equations derived from the theory developed for the GeoChron model ensure model consistency at each restored stage. As the only essential input is a GeoChron model, this restoration technique does not require any specialist knowledge and can be included in any existing structural model-building workflow as a standard validation tool. A model can quickly be restored to any desired stage without providing input mechanical parameters for each layer nor defining boundary conditions, enabling geologists to iterate on the structural model and refine their interpretations until they are satisfied with both input and restored models.