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Building a High-resolution Model with Full Waveform Inversion in Deep Water West Africa
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 76th EAGE Conference and Exhibition 2014, Jun 2014, Volume 2014, p.1 - 5
Abstract
Full waveform inversion (FWI) can provide high-resolution velocity models and find more details in velocities than ray-based tomography technologies. However, FWI requires a relatively accurate initial velocity model, data with good low-frequency signal content, and an accurate source signature. In our case we successfully apply FWI in a deep water area of offshore Angola. Our FWI benefits from a good initial velocity model created by ray-based high-definition tomography and variable-depth streamer data, which has good low-frequency signal content, and an accurately estimated source signature from near-field hydrophone data. We use reflected and diving waves from our 8 km offset data, enabling FWI to update the velocity as deep as approximately 5 km. The FWI updated velocity around shallow anomalies and faults is more accurately defined than the velocity from ray-based tomography. Even at the deeper Albian and shallow pre-salt levels, FWI is able to improve the velocity, producing a better migrated stack and improving gather flatness.