Prestack reverse-time migration in anisotropic media

Martin Karrenbach

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ABSTRACT

The finite-difference method used with the full two-way wave equation can model all wave phenomena exhaustively and provides correct amplitude information at reflectors. Reverse time migration, or conjugate-gradient inversion, uses conjugate modeling to arrive at an approximate inverse to the forward modeling process. Reverse time migration is expensive compared to one-way wave equations or algorithms with simplified reflection geometry, but it handles all amplitudes properly and includes all wave propagation phenomena. Reverse time migration is suggested as the preferred tool for detailed medium property identification.I show a two-dimensional example, where elastic siffnesses in an anisotropic media can be imaged and determined by crosscorrelating strain components of a forward-modeled shot wave field with strain components of the backward-propagated data wavefield.