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Revealing Shallow and Deep Complex Geological Features with FWI - Lessons Learned
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 79th EAGE Conference and Exhibition 2017, Jun 2017, Volume 2017, p.1 - 5
Abstract
Conventional full waveform inversion (FWI), mostly based on diving waves, has become a standard velocity model building tool. Using a deep water dataset from the Mexican side of the Gulf of Mexico (GoM), we show that FWI can be effective at resolving different types of complex geological features in the shallow overburden. Unfortunately, it is well known that below the diving-wave penetration depth, FWI has to rely solely on reflections. In this case, the velocity update is dominated by high-wavenumber components and the inversion dependence on the accuracy of the density model increases. However, we show that the reflections can still help solve for the low wavenumbers of the velocity model when different components of the FWI gradient are used separately for reflection-wave-based full waveform inversion (RFWI). This allowed reflection data to improve the velocity model at a geologically challenging location within our GoM project area, namely where traditional ray-based tomography failed and the depth of the required updates exceeded the diving-wave penetration. We discuss the lessons learned for RFWI from this example.