We investigate the simulation of viscoacoustic wave propagation and reverse time migration (RTM) in transversely isotropic (TI), vertical TI (VTI) and tilted TI (TTI) media, within a constant approximation. Such wave propagation can be modelled with a finite difference scheme by introducing a series of standard linear solid (SLS) mechanisms, and it can be carried out within a tractably small computational region by making use of perfectly-matched layer (PML) boundary conditions. A viscoacoustic wave equation for VTI and TTI media can be derived as in the non-attenuative case using the wave equation in anisotropic media as a starting point and setting the shear wave velocity to zero. Using the TI approximation and ignoring all spatial derivatives in the anisotropic symmetry axis direction leads to instabilities in areas of the model with the rapid variations in the symmetry axis direction. A solution to this problem is proposed that involves selectively equating anisotropic parameters within the model to reduce Thompson parameter differences in problem areas. To eliminate high-frequency instabilities, we apply a regularization operator, which results in a stable viscoacoustic wave propagator in TI media. After correcting for the effects of anisotropy and , RTM images are shown with synthetic examples to carry higher resolution information than VTI RTM images alone.
Presentation Date: Wednesday, October 17, 2018
Start Time: 1:50:00 PM
Location: 205A (Anaheim Convention Center)
Presentation Type: Oral