Velocity images from stacking depth-slowness seismic wavefields

Abstract

International audienceWe present synthetic and real data examples processed using a depth imaging method for long-offset multichannel seismic data via the intercept-time-slowness (τ-p) domain. The refracted and reflected information contained in the wavefield is processed simultaneously. Our scheme uses common midpoint data that is transformed to the τ-p domain and mapped to the depth-slowness (z-p) domain using a downward continuation algorithm. The velocity function for downward continuation may be obtained iteratively from the diving ray trajectory within the slowness-depth wavefield or estimated using an independent method. Horizontal events within the z-p wavefield are isolated by applying a mute function corresponding to the downward continuation velocity function in the z-p domain. Stacking the resulting wavefield gives an image trace that may be superimposed on the velocity function to form a velocity image. Following testing on synthetic data the method is applied to two long-offset marine seismic streamer data sets with offsets up to 18 km, from the northeast Atlantic margin. These examples demonstrate the potential of the method to obtain velocity images in difficult geological locations, where conventional processing has been less successful

What do you think this is? “Conceptual uncertainty” in geoscience interpretation

“…Quantification of uncertainty in geological framework models in petroleum geoscience has concentrated on such parameters as the petrophysical properties of reservoirs (e.g., Egermann and Lenormand, 2005) and the resolution and processing of seismic data (e.g., Jones et al, 2007). In petrophysical models, predictions of reservoir permeability are based on water saturation data (Aguilera, 2004), pressure measurements, log data, well cores (Yan et al, 2006), and the like.…”

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“…F3). The strong D-reflection, noted by Canales et al (2004) to be pervasive throughout the dome and apparently an isolated event at 0.2-0.5 s two-way traveltime using initial processing, has been shown via a wide-angle reflection processing method (Masoomzadeh et al, 2005;Jones et al, 2007) to most likely be the first in a series of reflections ( Fig. F2) (Singh et al, 2004).…”