We develop the theory of n-stacks (or more generally Segal n-stacks which are∞-stacks such that the morphisms are invertible above degree n). This is done by systematically using the theory of closed model categories (cmc). Our main results are: a definition of n-stacks in terms of limits, which should be perfectly general for stacks of any type of objects; several other characterizations of n-...

Least-squares reverse-time migration (LSRTM) provides image of reflectivity with high resolution and compensated amplitude, but the computational cost is extremely high. One way to improve efficiency is to encode all of shot gathers into one or several super-shot gathers with designed encoding functions so as to solve a smaller number of wave-equations at each iteration. Another way is to use d...

With finite capital and logistical means, interpolation is a necessary part of seismic processing, especially for such data-dependent methods as surface-related multiple elimination. One such method is to first estimate a prediction-error filter (PEF) on a training data set, and then use that PEF to estimate missing data, where each step is a least-squares problem. This approach is useful becau...

Three-dimensional seismic wavefields may be extrapolated in depth, one frequency at a time by two-dimensional convolution with a circularly symmetric, frequencyand velocity-dependent filter. This depth extrapolation, performed for each frequency independently, lies at the heart of 3-D finite-difference depth migration. The computational efficiency of 3-D depth migration depends directly on the ...

Historically though, 3D marine streamer acquisition has been forced to compromise spatial sampling in the name of efficiency and cost. This compromise translates to noise and degraded resolution when processing the data. A significant component of the seismic “noise” contaminating 3D images actually arises during processing, as an unfortunate and inescapable artifact from poor 3D spatial sampli...

Abstract With the development of seismic surveys and decline shallow petroleum resources, high resolution signal-to-noise ratio have become more important in processing. To improve quality data, stationary-phase migration based on dip-angle gathers can be used to separate reflected waves noise. However, this method is very computationally intensive heavily dependent expert experience. Neural ne...

We investigate the sensitivity of AVO attributes to uncertainty in migration velocity in a synthetic dataset. The synthetic data was built using a earth model with typical rock properties from a real North Sea turbidite field. The model includes a thick overburden layer with complex velocity anomalies. We examine the sensitivity of AVO response due to the presence of this complex layer and quan...