Signatures of Fracture and Stress Induced Anisotropy

The main causes of azimuthal anisotropy in hydrocarbon reservoirs are anisotropy of the horizontal stresses and presence of vertical or dipping fractures. The aim of this paper is to analyse and compare anisotropy patterns associated with these two causes of anisotropy. Stresses affect elastic properties of rocks due to presence of discontinuities such as cracks and compliant grain contacts.