Waveform Tomography of Marine Seismic Data: What Can Limited Offset Offer ?

In a followup to our participation in the 2004 BP velocity benchmark (Pratt and Brenders, 2004), we present a refined application of waveform tomography traveltime tomography followed by frequencydomain waveform inversion to estimate the (previously unknown) velocity model. Due to the importance of direct (refracted) energy, the limited offset of marine seismic streamers provides a fundamental limit to the depths tomographic techniques can accurately image. In addition, we present the results of waveform tomography using data simulating two-ship experiments, providing total offsets of up to 32 km. We use the 2004 BP velocity benchmark dataset to illustrate the ability of waveform tomography to delineate top-salt and image shallow, low-velocity anomalies.