3-D prestack common-azimuth depth migration (CAM) has strong potential for accurately imaging complex media and correctly handling multi-pathing. Here, we apply the technique to a North Sea dataset recorded over a salt dome region. The results obtained demonstrate the suitability of the method for complex media, and illustrate important differences with Kirchhoff methods. A detailed analysis of...

Reflection amplitude as a function of offset is effective in characterizing lithology in oil producing basins. Experience shows that AVO inversion methods based on amplitude-preserved prestack migration typically provides a more accurate lithology estimation than NMO-based AVO analysis. However, some artifacts may be introduced into the migration section, which can obscure the estimate of reser...

We develop a new one-way wave prestack depth migration method called Fourier integration (FI) method which uses the exact extrapolation operator and the exact velocity model without any approximations or assumptions. The work is performed on a CUDA (Compute Unified Device Architecture) based Graphic Processing Unit (GPU). Compared to the traditional one way wave method, the GPU version FI metho...

We demonstrate a method for 2D velocity estimation in complex media characterized by triplicated ray fields. Due to multipathing, Migration Velocity Analysis (MVA) principle has to be revisited, requiring in particular the use of Common Angle Gathers (CAGs) instead of the classical common offset panels. For the inversion itself, locally coherent events are automatically picked in the prestack d...

Wave-equation migration velocity analysis is a two-step process: first, we estimate the perturbation between a starting image and a better-focused image, and then invert for the perturbation in slowness that explains the perturbation in image obtained in the first step. The key to success is to obtain a sharp image, with flat common-image gathers at every location. In this paper, I show how pre...

In chapter 10 migration is described in terms of double focussing. In chapter 11 focussing in emission is used to synthesize common focus point gathers (CFP gathers). By comparing aCFPgather with its related focussing operator velocity errors can be detected and the focussing operator can be corrected (Berkhout and Rietveld (1994), Rietveld and Berkhout (1994) , Berkhout (1992), Rietveld and Th...

Wave-equation dip moveout (DMO) addresses the DMO amplitude problem of finding an algorithm which faithfully preserves angular reflectivity while processing data to zero offset. Only three fundamentally different theoretical approaches to the DMO amplitude problem have been proposed: (1) mathematical decomposition of a prestack migration operator; (2) intuitively accounting for specific amplitu...

Wavefield extrapolation by spatially variable phase shift is currently a migration tool of importance. In this paper, we present a new prestack seismic migration algorithm using the Gabor transform with application to the Marmousi acoustic dataset. The imaging results show a very promising depth imaging algorithm, which is competitive with the best depth imaging algorithms. The Gabor depth imag...

Models of phonological short-term memory (pSTM) generally distinguish between two components: a phonological buffer and a subvocal rehearsal. Evidence for these two components comes, respectively, from the phonological similarity effect and the word-length effect which disappears under articulatory suppression. But alternative theories posit that subvocal rehearsal is only an optional component...