Poroelastic Reverse Time Migration Based on True-Amplitude Vector Wavefield Decomposition

As an accurate imaging method in exploration seismology, most of the current Reverse time migration (RTM) algorithms are designed for acoustic or elastic media, with limited applications in poroelastic medium. To address this limitation and minimize crosstalk artifacts during imaging, we propose a novel vector wavefield decomposition method specifically tailored for poroelastic media. This method enables the production of vector fast P-wave, slow P-wave as well as S-wave with correct phases and amplitudes. By utilizing the decoupled waves, we introduce a poroelastic reverse time migration workflow that allows high-resolution imaging of subsurface structures with varying porosities. We observe that fast and slow P waves exhibit distinct sensitivities to velocity and porosity anomalies. For instance, the fast P wave is adept at accurately imaging reflectors associated with velocity contrast, while the slow P wave demonstrates excellent performance in imaging porosity-related reflectors. In our numerical examples, we first test the accuracy of the wavefield decomposition method, followed by synthetic tests on layered models and the Marmousi2 model to showcase the disparate imaging characteristics of our proposed method for velocity and porosity.