Focusing Analysis In Transversely Isotropic Media

I study the application of migration to focusing analysis of seismic data acquired in transversely isotropic media. Focusing analysis is based on the sensitivity of migrated images to perturbations of anisotropic parameters. When these parameters are accurate, both imaging conditions of zero time and zero offset act in a complementary way to produce an accurately migrated image. Pre-stack migration has been largely used in seismic velocity determination (Gazdag and Squazzero, 1984; Yilmaz and Chambers, 1984; MacKay and Abma, 1992). In 1986, Jeannot et al. introduced a method which they called "depth-focusing analysis" that uses the velocity sensitivity of pre-stack migration for velocity-error estimation. Recently, Sena and Toksoz (1993) presented a velocity analysis method in transversely isotropic media, which is basically an extension for data acquired at the surface of the method proposed by Byun et al. (1989). In their velocity analysis algorithm, three different velocities, horizontal, vertical and skew, are obtained. They use the skewed hyperbola as defined by Byun et al (1989), where skewness is defined by the deviation of the skew velocity from the horizontal velocity. I present a study of the effects of anisotropy in depth focusing analysis of seismic energy and test the sensitivity of the migrated data to perturbation in the anisotropic parameters.