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, which is 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