Unlocking the potential of WAZ data for subsalt imaging using FWI: A case study in the Perdido area

Full-waveform inversion (FWI) has become the norm in velocity model building for different surveys from land to marine, and from streamers to ocean bottom nodes. FWI using wide-azimuth (WAZ) streamer data in areas with complex geologic settings can fall short of resolving the complexity when starting from a poor initial velocity model. Previous studies have shown that iterating salt scenarios and Time-lag FWI (TLFWI), an effective and stable FWI algorithm for salt, can lead to a better initial model for the next round of FWI and eventually result in a step-change in the salt model and the subsalt image, even when only using WAZ streamer data. However, this approach relies on RTM images for the evaluation of model updates, which are highly susceptible to illumination issues. The recently developed FWI Imaging algorithm can bolster the approach by reducing the impact of poor illumination for subsalt imaging, easing model evaluation. In our case study in the Perdido area, we employ TLFWI and FWI Imaging to maximize the value of WAZ data for velocity model building and subsalt imaging.