Wave-equation migration velocity analysis for VTI media using optimized implicit finite difference

Wave-equation migration velocity analysis for VTI media using optimized implicit finite difference

Yunyue (Elita) Li

Abstract:

Anisotropic wave-equation migration velocity analysis (WEMVA) requires fast and accurate wave modeling at all angles. I use an optimized implicit finite difference one-way propagation engine to improve both the efficiency and accuracy of this process. In this implicit finite difference scheme, anisotropic parameters $\eta$ and $\delta$ are mapped into two finite difference coefficients, $\alpha$ and $\beta$ . When computing the perturbed wavefields from model perturbation, I apply a chain rule to link the wave equation with the actual anisotropic parameters via the finite difference coefficients. I test the implementation by impulse responses in both 2D and 3D. The sensitivity kernels for wave-equation reflection tomography confirm the theoretical understanding that waves have a higher sensitivity for $\eta$ at large angles and a higher sensitivity for vertical velocity at small angles.

Wave-equation migration velocity analysis for VTI media using optimized implicit finite difference