P-Wave Traveltime Analysis and Thomsen Parameters Inversion in Orthorhombic Media

An orthorhombic (ORT) model is the simplest azimuthally anisotropic model used to describe realistic fractured reservoirs (e.g., vertical cracks embedded in an anisotropic background media or orthogonal fracture systems in purely isotropic matrix). In this paper, we calculate the omnidirectional reflection traveltime of P‐wave in single orthorhombic media with horizontal interface by using the ray trace method. The reflection Pwave traveltime‐distance curves show strong azimuthal anisotropy. Using the Niche Genetic Algorithms (NGA), inversion of reflection traveltime of three common‐midpoint (CMP) lines provides us with a good estimation of azimuth, P‐ wave vertical velocity and Thomsen anisotropic parameters.