Velocity continuation is an imaginary continuous process of seismic image transformation in the postmigration domain. It generalizes the concepts of residual and cascaded migrations. Understanding the laws of velocity continuation is crucially important for a successful application of time-migration velocity analysis. These laws predict the changes in the geometry and intensity of reflection ev...

I introduce a partial differential equation to describe the process of prestack reflection data transformation in the offset, midpoint, and time coordinates. The equation is proved theoretically to provide correct kinematics and amplitudes on the transformed constant-offset sections. Solving an initial-value problem with the proposed equation leads to integral and frequency-domain offset contin...

Abstract One of the primary purposes seismic stratigraphy is to evaluate components layer relationships within a depositional chronology. Prestack images contain wealth information, such as variations in offset and azimuth event, naturally produce higher-resolution facies analysis results than poststack data. However, prestack data usually suffer from potential unreliability issues due low sign...

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...

Prestack migration is necessary before AVO analysis. Most of the present migration algorithms not only try to focus the reflections on the subsurface but also strive to preserve the amplitude for subsequent amplitude studies. A migration/inversion method developed by Lumley (1993) estimates the angle dependent reflectivity at each subsurface point by using least-squares Kirchhoff migration foll...

We provide a kinematic analysis of the prestack image behaviour in the subsurface offset domain. When the medium properties are perfectly known, the image is expected to focus at the zero subsurface offset, where the incident and the scattering wavefields interact at a common point. However, kinematic artifacts are often observed in subsurface offset common-image gathers (CIGs) away from the ze...

Common-reflection-point (CRP) gathers provide important clues in various migration velocity analysis schemes (Al-Yahya, 1987; Etgen, 1990). Conventionally, CRP gathers are obtained by prestack migration of shot records or constant-offset sections. This paper introduces a way to generate a CRP gather for residual velocity analysis using wavefront synthesis imaging. Compared to CRP gathers obtain...

3-D prestack depth migration is emerging as an industrial imaging tool. Many competing algorithms have been proposed by various authors. Nevertheless, the real bottleneck in 3D prestack processes is the sheer amount of input and output data. This paper reviews the principal migration methods on the basis of their capacity for data manipulation, without evaluating the algorithms themselves. It c...