Full Waveform Inversion
Full Waveform Inversion (FWI) is a methodology that seeks to find high-resolution, high-fidelity velocity models of the subsurface capable of matching individual synthetic seismic waveforms with an original raw field dataset. This is achieved iteratively by determining and minimizing a residual; the difference between modeled and recorded data.
PGS FWI utilizes 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; in particular, in shallow-water environments where reflection based tomographic inversion methods are limited.
- 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 modeling
PGS FWI Benefits
- Uses diving waves, refractions and reflections together to reduce dependence upon very long offsets and 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