Full Waveform Inversion

Full Waveform Inversion (FWI) is a methodology that determines high-resolution, high-fidelity velocity models of the subsurface capable of matching individual modeled synthetic seismic waveforms raw recorded field data. This is achieved iteratively by determining and minimizing a residual, which is the difference between modeled and recorded data.

PGS FWI uses the full wavefield, so both diving waves (wavefronts continuously refracted upwards through the earth due to the presence of a vertical velocity gradient) and reflections. FWI is successful in resolving small-scale features, particularly where reflection-based tomographic inversion is challenged, such as shallow-water environments and around high-contrast bodies like salt and volcanics. 

FWI Fundamentals

  • Full Waveform Inversion is a velocity model building tool 
  • Earth models are refined by minimizing the difference between recorded data and the modeled data  
  • Historically only refractions were used and penetration depth was limited
  • PGS FWI uses the full wavefield for deeper updating

PGS FWI Benefits

  • Uses diving waves, refractions, and reflections together to reduce dependence upon very long offsets and to provide high-fidelity velocity models
  • Avoids cycle-skipping artifacts and delivers models with correct long-wavelength information
  • Removes migration isochron artifacts resulting in accurate deep velocity models
  • High-resolution deep velocity updates translate to improved subsurface images and robust reservoir characterization

 

PGS FWI
PGS FWI overcomes geological complexity to provide excellent resolution of a Paleocene canyon in deepwater Côte d’Ivoire.