Workshop Description

In the last twenty years the exploration geophysics community has developed impressive velocity model building and migration methods using acoustic wave equations. Numerous published results have shown the relevance of these approaches in both waveform inversion (which we abbreviate here as “FWI” by adding the common “full” to its description) and prestack reverse time migration. However, the Earth is better approximated by a visco-elastic assumption and we may be reaching the limits of the acoustic assumption as we move to velocity model building in ever more complex geological environments. Hence, this workshop will focus on the current directions in acoustic and elastic FWI for velocity model building.

Specific issues that we look to cover include:

Why is elastic modeling important in FWI?

• Does this matter more at low frequencies, or at high frequencies? 
• What is the impact of the different (acoustic and elastic) amplitude versus angle behavior on the inversion?
• Can phase-only or pre-processing approaches mitigate amplitude effects, and when are they valid?
  

In what environments is elastic modeling beneficial, or even mandatory?

• Offshore: where we have the acoustic/elastic water bottom boundary? Or where we have more general large-impedance contrasts, such as salt or chalk, or more localized high-contrast geo-bodies, in either the near surface or at depth? 
• Onshore: where the entire medium is elastic, including the area where we inject and extract the wavefield? 

Other related questions we look to discuss include: 

• How do elastic issues affect reflection FWI? Can it be acoustic-only if we consider only low-frequencies? 
• What does high-resolution mean in the context of velocity model building? 
• Can the benefits of elastic FWI justify its cost over acoustic FWI? 
• How does viscosity influence our conclusions?