Predicting Multi-scale Deformation and Fluid Flow Patterns in Folds Using 3D Outcrop Models and Mechanical Modelling

Natural fracture patterns in folded carbonates are highly heterogeneous. The present-day fractures are often the result of pre-folding, syn-folding and post-folding related fractures. Furthermore, syn-folding fractures may differ in different domains of the fold. Although there are studies that characterize fracture patterns in outcropping folds, there is still a poor understanding of the relation between large-scale deformation (i.e. folding), and small-scale deformation (i.e. fractures), especially in terms of stresses and process-based predictions of fractures. Our overarching goal is to assess the sensitivity of reservoir-scale flow to different fracture patterns and different fracture properties. Therefore we build multi-scale models of 3D fracture networks in outcropping folds in the foothills of the Tunisian Atlas (central Tunisia). The fracture data is collected from outcrops using efficient methods that collect both fractures and the 3D geometry of the outcrops. We interpret small-scale deformation in terms of stresses and combine this with fold-scale mechanical models to predict the fracture patterns in 3D throughout the fold. The 3D model is used to model fracture fluid flow. This work presents a new approach to outcrop studies, that distinguishes different stages of fracturing and uses stresses to make predictions about fracture patterns in similar structures.