Role of stress regime in azimuthal anisotropy of poroelastic media

The activation of the tectonic setting primarily affects the azimuthal anisotropy, as the poroelastic moduli vary. Seismic imaging to analyze wellbore stability and characterize the reservoirs must take azimuthal anisotropy into account. We investigated the azimuthal anisotropy during seismic processing to show the imaging improvement from isotropy to horizontal transverse isotropy states. We estimated the direction of anisotropy in the reservoir with horizontal transverse isotropy (HTI) moveout analysis and confirmed the results with the direction of active stresses obtained from imaging petrophysical logs and experimental tests. We developed the relationships between strains and stresses in the anisotropy state and combined the results with the failure criterion to express the point for critical pore pressure in breaking onset. We used the experimental analysis to determine the Biot coefficient. We then determined the compliance fractures and the horizontal stresses using the Mohr-Coulomb failure criterion. We evaluated the stresses in isotropic and anisotropic state and analyzed them in reservoir conditions. The study showed that the calculated stresses under anisotropic conditions are 26% higher than under isotropic conditions. This point must be taken into account in the wellbore stability analysis and the reservoir characterization.