Andrew Brenders

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.

Evaluation of Preconditioning Strategies On Waveform Tomography of Field Data: Success With Long Offset Seismic Data In a Thrust-fold Belt

In thrust-fold belt tectonic settings (e.g., the Canadian Foothills), conventional acquisition and (prestack time) processing of seismic data is often inadequate in producing an accurate sub-surface image. The presence of steep dips and large lateral velocity contrasts require both prestack depth migration methods and suitable seismic survey design (e.g., acquiring long offsets). As such, an accurate velocity model is required. A superior method of velocity model estimation, Waveform Tomography, can then be used to improve the sub-surface image. We apply this approach to 2-D, long-offset data acquired in the Canadian Foothills.