“Automatic velocity model building with complex salt: Can computers finally do an interpreter's job?”

Abstract

The requirements for a good seismic image are simply stated: appropriate data, suitable algorithms, and a good velocity model. Some might add a “friendly earth” to the list, since it is clear there are some areas where we have not yet discovered how to compute a good image, most notably beneath rugose, highly variable media. Over the past two decades, our seismic data and imaging algorithms have greatly improved. Increasing data density and wide azimuth acquisition, combined with improved demultiple techniques and anisotropic wave-theoretic migration have produced significant uplifts in our ability to image beneath complex salt. Velocity-model building has lagged behind: building models with complicated salt bodies continues to be a labor-intensive, hit-or-miss interpretation exercise that often produces unreliable results. The promise of Full-Waveform Inversion (FWI) - a fully-automatic, data driven, model-building process - has proved elusive, notwithstanding its significant impact in non-salt settings. Recent experience with the Atlantis field in the Gulf of Mexico has shown that automatic velocity-model building with FWI is also possible for salt. When applied to ocean-bottom seismic data acquired with wider offsets and lower frequencies than previously recorded, FWI produced a velocity model that dramatically improved the seismic image at Atlantis. Presentation Date: Monday, September 25, 2017 Start Time: 3:05 PM Location: 351F Presentation Type: ORAL