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Introduction

Migration Velocity Analysis (MVA) and Amplitude Versus Angle (AVA) analysis are the two main applications of Angle-Domain Common-Image Gathers (ADCIGs). ADCIGs can be computed in the Fourier domain from offset-domain images generated by wavefield-continuation methods Sava and Fomel (2000). In previous work Tisserant and Biondi (2003), we presented an extension of the method to make it valid for 3-D geometries. Biondi and Symes (2003) analyze the kinematics of ADCIGs when an incorrect migration velocity has been used during the wavefield-continuation step. This paper aims to extend their analysis to 3-D.

We consider two approaches: one based on rays, the other based on plane-waves. In the ray approach, we split our analysis between the use of an correct and an incorrect migration velocity. When the migration velocity is correct, the source and receiver rays focus at the same correct image point where they are coplanar. This property of the rays makes it simple to transform the 3-D geometry into 2-D for which the theory is available Biondi and Symes (2003). We then analyze the problem when an incorrect migration velocity is used. Incorrect migration velocity yields non focused ray resulting in an apparent image point, and generally not coplanar rays. We introduce an apparent propagation plane in which the 2-D theory can be applied. We will then discuss a plane-wave approach of the problem. Finally a synthetic example is used to verify our theoretical results.


next up previous print clean
Next: Geometry Up: Tisserant and Biondi: 3-D Previous: Tisserant and Biondi: 3-D
Stanford Exploration Project
10/14/2003