A Geologically Consistent Permeability Model of Fractured Folded Carbonate Reservoirs: Lessons from Outcropping Analogue

Presently adopted fracture-related permeability models of large folded reservoirs are simplistic and often unrelated to the geological setting and evolution of the considered structure. In order to improve predictions of fluid flow in more complex subsurface fractured reservoirs, we build a 3D fracture network model of an outcropping fold in Tunisia, and populate different structural domains with fracture data, collected from outcrops. Within the studied fold, we find large variations in deformation mechanisms between different formations, with the main mechanisms being Layer Parallel Shortening (LPS), resulting in regional deformation, and the more localized impact of fiber stresses and flexural slip. Within the steep flank of the anticline, we find that in one formation fracturing is mostly controlled by fiber stresses, whereas in the underlying formation flexural slip is the main deformation mechanism. These two formations are separated by a detachment surface. Using stress and strain fields, we aim at reconstructing the conditions at which these fractures have been formed. This can provide a better understanding of the relation between fracture patterns in different structural domains of a fold and the stress evolution that formed these fractures, and the subsequent impact of different fracture patterns on fluid flow in fractured folds.