Thematic Set: Full waveform inversion of a deep water ocean bottom seismometer dataset

Improvements in seismic acquisition, such as the collection of long-offset and wide-azimuth data, coupled with the increase in computer power have made full waveform inversion methods based on the minimization of the residuals between modelled and observed data viable. Here we present results from the application of full waveform inversion to an ocean bottom seismometer dataset recorded in the Gulf of Mexico. First, an isotropic formulation is applied to show the relevance of this approach for capturing fine details, such as gas accumulations, in the shallow part of the velocity model where the diving waves propagate. Also, to produce flatter common image gathers in the deep part of the model, an anisotropic formulation with a fixed ratio between the horizontal and the vertical velocities is used. This real example shows that full waveform inversion is an affordable approach in 3D for velocity analysis, at least with certain types of datasets, even though it is not a standalone method. It also illustrates the benefit of improving the shallow part of the velocity model to better image the deeper part.