Velocity continuation and the anatomy of residual prestack time migration
نویسنده
چکیده
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 events on migrated images with the change of the migration velocity. In this paper, I derive kinematic and dynamic laws for the case of prestack residual migration from simple geometric principles. The main theoretical result is a decomposition of prestack velocity continuation into three different components corresponding to residual normal moveout, residual dip moveout, and residual zero-offset migration. I analyze the contribution and properties of each of the three components separately. This theory forms the basis for constructing efficient finite-difference and spectral algorithms for timemigration velocity analysis.
منابع مشابه
Migration and velocity analysis by velocity continuation
Residual and cascaded migration can be described as a continuous process of velocity continuation in the post-migration domain. This process moves reflection events on the migrated seismic sections according to changes in the migration velocity. Understanding the laws of velocity continuation is crucially important for a successful application of migration velocity analysis. In this paper, I de...
متن کاملPrestack imaging of overturned reflections by reverse time migration
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...
متن کاملPrestack imaging of overturned and prismatic reflections by reverse time migration
I present a simple method for computing angle-domain Common Image Gather (CIG) 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 shotprofile migration. I demonstrate with a synthetic example the use of the CIG gathers for migration velocity updating. A challenge for imaging both o...
متن کاملTomographic velocity estimation with planewave synthesis imaging
In areas with structurally complex geology, tomographic velocity analysis is required to estimate velocities. This paper describes a tomographic velocity analysis algorithm which uses planewave synthesis imaging as a prestack migration. In reflection tomography, prestack migration is required for both event picking and traveltime error computation. Traveltime errors are often measured in the fo...
متن کاملWave-equation migration velocity analysis by inversion of differential image perturbations
Wave-equation migration velocity analysis is based on the linear relation that can be established between a perturbation in the migrated image and the corresponding perturbation in the slowness function. Our method formulates an objective function in the image space, in contrast with other wave-equation tomography techniques which formulate objective functions in the data space. We iteratively ...
متن کامل