Optimized Acoustic Approximation and Simulation of P-Wave in Transversely Isotropic Media

Abstract

Summary The standard acoustic approximation in transversely isotropic (TI) media results in an approximate P-wave phase velocity expression with a complicated square root term. Thus, the corresponding wavefields suffer from the unstable SV-wave artifacts. Many subsequent pure P-wave simulation methods were proposed to eliminate the SV-wave artifacts at the expense of decreasing the accuracy or increasing the computing cost. In this abstract, we propose an optimized acoustic approximation for P-wave in TI media to overcome the defect of the standard acoustic approximation. Since the P-wave propagation is weakly dependent on the vertical S-wave velocity, we construct a function of the vertical S-wave velocity squared to approximate the P-wave phase velocity. The corresponding expression is quite concise, without square roots and complicated fractions. Then, we derive a pure P-wave equation in tilted transversely isotropic (TTI) media. We compare and analyze the wavefields of several simulation methods in the homogeneous and complex TTI models. The wavefields of the proposed method only involve the P-wave propagation with high accuracy. And the computing cost is acceptable. So, this optimized acoustic approximation and the corresponding pure P-wave simulation method can be further used for the reverse time migration and full waveform inversion in TI media.