Effects of Seismic Anisotropy on Target Depth Determination in Geothermal Exploration

The characterization of geothermal reservoirs is primarily based on seismic imaging techniques. In most cases the underlying physics of seismic wave propagation relies on an isotropic acoustic or elastic approximation. In this study we investigate the effect of elastic anisotropy on the depth estimation of geothermal target horizons in seismic images. Realistic values for Tilted Transverse Isotropy (TTI) anisotropic elastic models are estimated from in-situ HP/HT laboratory ultrasonic measurements of rock samples from a geothermal reservoir in southern Tuscany (Italy). Seismic imaging by anisotropic Reverse Time Migration of numerical scattering experiments and reflection seismic data from the study area reveal a vertical displacement of up to 500 m for geothermal target layers compared to the isotropic elastic case.