FINITE-DIFFERENCE REVERSE-TIME MIGRATION BASED ON ANISOTROPIC PURE QP WAVE EQUATION IN TTI MEDIA.

The anisotropic effects in real earth media can induce waveform distortion on seismic wave propagation. Neglecting these effects in seismic imaging processing can lead to a degradation in imaging resolution. Therefore, starting from the exact P-wave dispersion relation, we derive a pure acoustic wave equation for tilted transversely isotropic (TTI) media to accurately characterize the anisotropic effects. In contrast to the coupled pseudo-acoustic TTI wave equation, our new pure acoustic TTI wave equation generates a noise-free wavefields and remains stable for anisotropic parameters (ε < δ). The newly derived pure acoustic TTI wave equation accurately simulates the P-wave kinematic features, as demonstrated through theoretical analysis. Additionally, building on the proposed wave equation, we formulate a finite-difference operator and obtain a pure acoustic TTI wave equation that can be solved by finite-difference (FD) method. Numerical tests illustrate that the proposed FD-solvable pure acoustic TTI wave equation is highly efficient in wavefield simulation. Finally, based on the newly derived FD-solvable pure acoustic TTI wave equation, we implement TTI reverse time migration (TTI RTM). Numerical examples demonstrate the efficacy of the proposed TTI RTM scheme in correcting for anisotropic effects.
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