Learning to Unflood the Salt in Full-Waveform Inversion, Application on Vintage GOM Data

Abstract

Building a velocity model in salt provinces is a challenging task. Traditionally the salt boundaries is manually interpreted by an iterative process of imaging, picking the top of the salt and flooding, re-imaging and picking the bottom of the salt for unflooding. This workflow is time-consuming and prone to errors. Full-waveform inversion (FWI) can be used to correct the erroneous picks of the salt boundaries. However, it requires low frequency and long offsets data to build an accurate salt body. We apply an FWI-based automatic unflooding process on vintage field data that do not meet these requirement by training a neural network using data with similar characteristics. The network is trained to unflood the salt and estimate the subsalt velocity from an inverted flooded model in a regression manner. The network shows good potential to unflood the vintage data and produce results comparable with the legacy model.