Relatively amplitude-preserved ADCIGs based on elastic RTM by modifying the initial condition as the boundary condition

Abstract

Compared with one-way wave equation migration methods, reverse-time migration has advantages in the aspects of amplitude preservation. In this paper, we extend the angledomain true-amplitude acoustic reverse-time migration to elastic case. First, we propose to modify the source term as the boundary condition to reconstruct the vector source wavefield and use the true-amplitude wavefield separation method to obtain amplitude-preserved P-and S-waves. Then, the extended imaging condition and angle decomposition procedure are applied to obtain the relatively amplitude-preserved angle-domain common image gathers. In numerical examples, we carry out the amplitude preservation analysis by comparing the peak amplitudes of the angle-domain common image gathers with the theoretical reflection coefficients calculated by solving the Zoeppritz equations. The results demonstrate that the angle-domain common image gathers are not only kinematically correct but also relatively amplitudepreserved.

Elastic least-squares reverse time migration using the energy norm

“…Even if anisotropy and elasticity are assumed in wavefield migration, such limitations still exist. Consequently, this type of migration often leads to images with poor resolution and unbalanced illumination due to such practical acquisition constraints, even though image amplitudes are more reliable when compared with acoustic and/or isotropic imaging (Lu et al, 2009;Phadke and Dhubia, 2012;Du et al, 2014;Hobro et al, 2014).…”