Prestack depth migration provides a powerful tool for velocity analysis in complex media. Both prominent approaches to velocity analysis—depth-focusing analysis and residual-curvature analysis, rely on approximate formulas to update velocity. Generally, these formulas are derived under the assumptions of horizontal reflector, lateral velocity homogeneity, or small offset. Therefore, the convent...

5D interpolation followed by azimuthal prestack migration results in better conditioned gathers for Amplitude Versus Offset (AVO) and Amplitude Versus Azimuth (AVAz) analysis. The data should be prestack migrated prior to AVO or AVAz analysis, but this often proves problematic for land data due to the poor sampling of the data in offset and azimuth. This sparse sampling results in incomplete co...

In areas of complex geology, migration-velocity estimation should use methods that describe the complexity of wavefield propagation, such as focusing and defocusing, multipathing, and frequency-dependent velocity sensitivity. Migration-velocity analysis by wavefield extrapolation has the ability to address these issues because, in contrast to ray-based methods, it uses wavefields as carriers of...

We present a simple method for computing angle-domain Common Image Gathers (CIGs) using prestack reverse time migration. The proposed method is an extension of the method proposed by Rickett and Sava (2001) to compute CIGs by downward-continuation shot-profile migration. We demonstrate with a synthetic example the use of the CIG gathers for migration velocity updating. A challenge for imaging b...

Velocity model estimation from seismic data using prestack depth migration is an un-derdetermined problem: there are many subtly diierent models which are not kinematically equivalent. As these models can give rise to dramatically diierent interpretations and decisions there is a clear need for a selection criterion in order to choose the "best" (i.e. geologically most plausible) one. Interpret...

Shot profile migration provides a convenient framework for implementation of a differential semblance algorithm for estimation of complex, strongly refracting velocity fields. The objective function minimized in this algorithm may measure either focussing of the image in offset or flatness of the image in (scattering) angle. The gradient of this objective is a by-product of a depth marching sch...

Abstract In the framework of non-destructive-testing advanced seismic imaging techniques have been applied to ultrasonic echo data in order examine integrity an engineered test-barrier designed be used for sealing underground nuclear waste disposal site. Synthetic as well real multi-receiver acquired at test site were processed and imaged using Kirchhoff prestack depth migration reverse time (R...

Abstract. We have used several flooding-induced microseismic events that occurred in an abandoned mining area to image geological structures close the hypocentres vicinity of mine. The been located using a migration-based localization approach. recorded full waveforms these localized and processed passive source data as if they resulted from active sources at known hypocentre location origin ti...

Standard imaging techniques rely on the single scattering assumption. This requires that the recorded data do not include internal multiples, i.e. waves bouncing multiple times between layers before reaching the receivers at the acquisition surface. When multiple reflections are present in the data, standard imaging algorithms incorrectly image them as ghost reflectors. These artifacts can misl...

The objective of seismic imaging is to obtain an image of the subsurface reflectors, which is very important for estimating whether a reservoir is beneficial for oil/gas exploration or not. It can also provide the relative changes or absolute values of three elastic parameters: compressional wave velocity Vp, shear wave velocity Vs , and density ρ. Two ways can achieve the objectives. In approa...