The Interplay between Fracture Apertures and Critical Stresses in a Naturally Fractured Carbonate Reservoir in Saudi Arabia

This study explores the relationship between natural fracture aperture and in situ local stresses and how their interplay define preferential direction of fluid flow in fractured carbonate reservoirs. Fracture aperture and the effect imposed by present day stresses is rarely characterized. We applied a workflow that links fracture aperture averages estimated from fractures detected by micro resistivity image logs and then we calculated shear and normal stresses on those fracture planes. Results showed that two main fracture orientations exhibit large fracture aperture and are critically stressed. The identification of these two critically stressed fracture sets was the main driver to estimate fracture permeability during the construction of the 3D reservoir fracture model. Directional patterns observed from fluid velocity data corresponds with the orientation of critically stressed facture sets. Incorporation of this workflow is improving our natural fracture prediction workflows by adding an in situ estimation of fracture permeability.