Full waveform inversion (FWI) in time for seismic data acquired using a blended geometry

This work presents the development of a FWI method in time, that uses seismic data acquired using a blended geometry. Blended geometry involves temporal and spatial overlap of multiple shots, randomly located in the same acquisition, whereas the traditional acquisition uses regular spacing of the receivers and one single shot at a time. The FWI method uses the acoustic wave equation with constant density 2D to find the modeled data, and a ℓ₂-error norm as misfit function between the observed and modeled data. The blended geometry acquisition was designed to obtain synthetically the seismic data at the surface with 5 shots simultaneous, using the Marmousi model of size 3.025 km × 12.425 Km (with a grid of 121 × 497 points) as true subsurface velocity model. The FWI method estimates the velocity using an smoothed version of the Marmousi as initial model, and it updates the velocity model iteratively using a gradient descent method. The FWI method for blended and traditional geometries was implemented and tested on the same computer under controlled conditions, for the same number of shots and iterations. The experimental results of the velocity models obtained using blended and traditional geometries have similar quadratic error norm, and the execution time of the FWI for the blended acquisition is up to 1.88 times faster than the FWI method for the traditional acquisition.