Technical Paper: Stabilizing acoustic reverse-time migration in TTI media

Society: SEG
Paper Number:
Presentation Date: 2009
 

We propose a new stable wave equation for tilted transversely isotropic (TTI) media that can be solved as part of an acoustic anisotropic reverse-time migration (RTM) algorithm using standard explicit finitedifferencing. If the shear velocity along the axis of symmetry is set to zero, stable numerical solutions can be computed for vertical transversely isotropic (VTI) media and epsilon not less than delta. In TTI media with rapid variations in the direction of the axis of symmetry, setting the shear velocity along the axis of symmetry to zero can cause numerical solutions to become unstable. A solution to this problem is proposed which involves using a small amount of non-zero shear velocity. The amount of shear velocity added is chosen to remove triplications from the SV wavefront and to minimize the anisotropic term of the SV reflection coefficient. We show stable wave propagation in complex TTI media using this equation.

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