An angle-dependent reflection coefficient is recovered by seismic migration in the angle-domain. We propose a post-migration technique for computing scattering and dip angle common-image gathers (CIGs) from seismic images, extended by the subsurface offset, in relation with wave-equation migration methods. Our methodology suggests a system of Radon transform operators by introducing local trans...

The quality of the migration/inversion in seismic re ̄ection is directly related to the quality of the velocity macro model. We present here an extension of the differential semblance optimization method (DSO) for 2-D velocity ®eld estimation. DSO evaluates via local measurements (horizontal derivatives) how ̄at events in common-image gathers are. Its major advantage with respect to the usual cos...

This paper explores the relationship between velocity uncertainty and AVO-related seismic attributes in a dataset from the Blake Outer Ridge, offshore from Florida and Georgia. From an initial velocity model, several realizations were generated that are perturbations of the original velocity model. Prestack wave-equation migration was applied to the data for each velocity realization. In the mi...

Seismic images reconstructed by migration from seismic data recorded at the surface represent the earth structure at every location in the subsurface. The data are remapped into the subsurface by using a wave equation and an estimate of the earth velocity. The velocity model is of great importance for obtaining accurate seismic images and for understanding the subsurface reservoir properties an...

Conventional crosswell surveys are expensive because a source must be placed downhole, which means that the hole must be prepped and placed off-line for a number of days. We suggest an interesting but unproven alternative: place a source on the surface, drop a simple obstruction-like device downhole that scatters tube wave arrivals from the surface source, and use the scattered tube waves energ...

We present a massively parallel algorithm for distributed-memory platform to perform 2D acoustic frequency-domain Full-Waveform Inversion (FWI) of global offset seismic data. Our code is written in Fortran 90 and uses Message Passing Interface (MPI) for parallelism. The linearized inverse problem is solved by a classical gradient method which consists in finding a model perturbation which minim...

Internal multiple prediction remains a high-priority problem in seismic data processing, such as subsurface imaging and quantitative amplitude analysis inversion, particularly the common-midpoint (CMP) gathers, which contain multicoverage reflection information of subsurface. multiples, generated by unknown reflectors complex environments, can be reconstructed with certain combinations events u...

In seismic data processing, we often need to interpolate and extrapolate missing data at spatial locations. The reconstruction problem can be posed as an inverse problem where from inadequate and incomplete data we attempt to reconstruct the seismic wavefield at locations where measurements were not acquired. This thesis presents a wavefield reconstruction scheme called minimum weighted norm in...

We introduce a digital wavelet-like transform, which is tailored specifically for representing seismic data. The transform provides a multiscale orthogonal basis with basis functions aligned along seismic events in the input data. It is defined with the help of the wavelet lifting scheme combined with local planewave destruction. In the 1-D case, the seislet transform is designed to follow loca...

Receiver-side water-column multiples acquired with ocean-bottom seismic sensors can be used for elastic imaging of the subsurface, which can provide additional information relative to more conventional acoustic imaging. These multiples can be separated from primaries contained in ocean-bottom seismic data using techniques such as up/down decomposition. In elastic imaging, the down-going wavefie...