PS-Wave Angle-Domain Imaging With Gaussian Beam Summation in 2-D TTI Media

Imaging PS-wave is essential for converted wave exploration, especially in tilted transversely isotropic (TTI) media. Compared with the relatively low imaging accuracy of anisotropic time migration for complex structures, an accurate anisotropic PS-wave depth migration approach would be preferable. As an effective depth migration technique, Gaussian beam summation (GBS) migration can provide high-precision imaging for complex geological structures. In this letter, we extend the GBS to PS-waves imaging in anisotropic media and present an angle-domain GBS migration method for converted waves in 2-D TTI media. We first introduce the anisotropic ray-tracing-based angle-domain GBS imaging condition of PS-waves in TTI media, in which the sign of the incidence angle of P-waves is applied to decide the PS-wave polarity. After calculating the propagation angles at imaging points by using the data of real-value travel time of anisotropic Gaussian beams, we can get the P-wave incidence angles and then extract the corresponding PS-wave angle-domain common-image gathers (ADCIGs). The performance of our method is verified by two numerical tests, indicating that it is an effective migration algorithm for accurately imaging converted waves in 2-D TTI media.