Amplitude-preserved Gaussian beam migration based on wave field approximation in effective vicinity under rugged topography condition

Abstract

Gaussian beam migration combines the ray theory with wave theory, which not only retains the advantage of Kirchhoff migration, such as flexibility, efficiency and nature adaptability for rugged topography, but also has high imaging accuracy like wave equation migration. A method of the amplitude-preserved Gaussian beam migration based on wave field approximation in effective vicinity under rugged topography condition is developed in this article. By considering the elevation, dip angle of rugged topography, we derived the forward and inverse wave extrapolation formula in terms of Gaussian beam, and then applied them to deconvolution imaging condition to obtain the formula of amplitude-preserved Gaussian beam migration in shot domain. Comparing to conventional local static correction method, our method not only applies more correction of travel time caused by rugged topography to improve the imaging quality in terms of kinematics, but also gives full consideration to the influence on the amplitude caused by rugged topography to improve the imaging quality in terms of dynamics. The trial of numerical models proved the above conclusion.