f Elastic (Visco) Full Waveform Inversion of multi-component marine seismic data in the time domain: A tribute to Albert Tarantola

(AVO) analyses can be used to estimate P and S-wave impedances. Since the method is local, i.e. assumes 1D media, linear approximation to the reflection coefficient, and ignores interference effects, the results are very approximative. In 1980s Tarantola’s group in Paris started developing elastic full waveform of near offset, while other groups were focusing on different types of migration algorithm using more sophisticated mathematical techniques. Tarantola (1986) first set-up the mathematical foundation of full waveform inversion in acoustic media and then extended it to full elastic media (Tarantola, 1988). In early 1990s our group started working on 1D elastic full waveform inversion (Singh et al, 1993) but used long offset data to get medium to large-scale velocity of the sub-surface. We showed that wide-angle reflection data (Neves and Singh, 1996) has sensitivity to intermediate wavelength information. Joint inversion of near- and post-critical angle reflections data allowed convergence towards the global minimum (Shipp and Singh, 2002). Since then we have extended the algorithm to multi-component OBC data to invert P and S-wave velocity (Sears et al., 2008; Roberts et al., 2008) and recently for attenuation (Royle and Singh, 2010). We start inverting wide-angle data first, followed by critical angle and then near offset data. For a stable inversion, we invert P-wave velocity first from vertical component data, then medium scale S-wave velocity vertical component and finally short wavelength S-wave velocity from horizontal component data. Although, our group has made significant progress, computation remains a main issue in applying elastic full waveform inversion on a routine basis. In this talk, I will give a historical prospective of elastic full waveform inversion, particularly those related to work of Albert Tarantola, and then present state of the art techniques of full elastic waveform and then propose a strategy for future waveform inversion. I will particularly highlight the importance of elastic inversion for reservoir characterization, and show how the full elastic waveform inversion could be extended to 3D media in a time-lapse mode (Royle and Singh, 2010; Queisser and Singh, 2010). We are presently taking full waveform a step further by jointly inverting both seismic and controlled source electromagnetic data (Brown et al, 2010).<br>