FWI Velocity Model Building Experiences
M.J. Hart, J. Sheng, S. Baldock and J. Mao
Event name: First EAGE/PESGB Workshop on Velocities
Session: FWI Case Studies I
Publication date: 22 February 2018
Info: Abstract, PDF ( 291.23Kb )
Full Waveform Inversion has been used to generate detailed models of shallow, subsurface velocity variations in some challenging areas. An accurate starting model was typically required to avoid cycle skipping. This could be minimised by incrementally increasing maximum offset, depth and traveltime over a number of iterations. We now incorporate dynamic warping into the early iterations of FWI to get around this problem, allowing us to start model building at the same time as time processing. Image-guided smoothing has also been utilised within FWI to minimise the effect of the acquisition footprint on the resulting velocity model and at the same time, provide structural constraints which further enhance the detail preserved within the model. Initially only diving wave energy was used, which limited the maximum update depth, dependent on offset. Recently we have been able to utilise WavePath FWI, which allows us to reliably use reflection events and constrain deeper updates into a more plausible model of the subsurface. Here we present some examples of our approach to model building with FWI over the past few years.