Double‐square‐root one‐way wave equation prestack tau migration in heterogeneous media

Abstract

A B S T R A C TIn this paper, source-receiver migration based on the double-square-root one-way wave equation is modified to operate in the two-way vertical traveltime (τ ) domain. This tau migration method includes reasonable treatment for media with lateral inhomogeneity. It is implemented by recursive wavefield extrapolation with a frequency-wavenumber domain phase shift in a constant background medium, followed by a phase correction in the frequency-space domain, which accommodates moderate lateral velocity variations. More advanced τ -domain double-square-root wave propagators have been conceptually discussed in this paper for migration in media with stronger lateral velocity variations. To address the problems that the full 3D double-square-root equation prestack tau migration could meet in practical applications, we present a method for downward continuing common-azimuth data, which is based on a stationary-phase approximation of the full 3D migration operator in the theoretical frame of prestack tau migration of cross-line constant offset data. Migrations of synthetic data sets show that our tau migration approach has good performance in strong contrast media. The real data example demonstrates that common-azimuth prestack tau migration has improved the delineation of the geological structures and stratigraphic configurations in a complex fault area.Prestack tau migration has some inherent robust characteristics usually associated with prestack time migration. It follows a velocity-independent anti-aliasing criterion that generally leads to reduction of the computation cost for typical vertical velocity variations. Moreover, this τ -domain source-receiver migration method has features that could be of help to speed up the convergence of the velocity estimation.

Dreamlet source‐receiver survey sinking prestack depth migration

“…In the midpoint‐offset algorithm, it has the advantage of large apertures, which reduces the need for extensive and irregular zero padding, especially for marine acquisition data. This feature attracts many researchers studying the survey sinking algorithm in the midpoint‐offset domain (Claerbout 1985; Popovici 1996; Jin, Mosher and Wu 2002; Cheng et al . 2008).…”