Full Waveform Inversion (FWI)

Full Waveform Inversion (FWI) is an advanced geophysical technique used to build highly detailed subsurface velocity models by leveraging the full information content of seismic wavefields. Unlike traditional methods that use only a portion of the seismic data (e.g. travel times), FWI uses the entire recorded waveform—both amplitude and phase—leading to more accurate and higher-resolution models of the subsurface. The goal is to minimise the difference between observed seismic data (recorded in the field) and synthetic seismic data (generated using an initial velocity model and forward modelling). FWI is particularly useful when dealing with areas of high heterogeneity, such as those caused by shallow glacial channels, gas bodies or tunnel valleys.

How FWI works:

1. Input Data

   • Observed Data: Recorded field seismic (reflections and refractions)

   • Initial Velocity Model: A starting approximation of the subsurface velocities, often created using simpler methods like tomography or well log data.

2. Forward Modelling

   • Simulates how seismic waves would propagate through the initial velocity model using numerical methods (e.g. finite difference, finite element).

   • Produces synthetic seismic data for comparison with the observed data.

3. Inversion Process

   • Compares the synthetic and observed seismic data to calculate a misfit (the difference between the two).

   • Gradients of the misfit are computed to update the velocity model iteratively.

   • The process repeats until the misfit is minimised.

4. Output: A high-resolution velocity model that reveals detailed subsurface structures and properties. This model can be pushed to higher frequency bands, which brings increasing computational demand.

   
   

With the essentially limitless computational capacity available to RockWave and through DUG-Insight, the most cutting-edge approach is to use Multi-Parameter FWI Imaging  (MP-FWI). When pushed to higher frequencies, this approach delivers a seismic image from raw data, without the need of running through a traditional processing sequence.

Related services: Depth Imaging;