Towards Joint Migration Inversion in TTI Media - Incorporating TTI Kinematics In Modelling and in Imaging

Abstract

Summary Joint Migration Inversion (JMI) is a recently developed method that inverts for the reflectivity, vertical velocity, and anisotropy models simultaneously. In its current implementation JMI can take into account Vertical Transverse Isotropy (VTI) kinematics. It is a fair assumption for horizontal anisotropic layers. However, for dipping anisotropic structures a VTI assumption is no longer adequate and an effective TTI medium must be considered. In this paper we consider and examine extending JMI to handle TTI kinematics. We start by including TTI kinematics in its modelling engine, Full Wavefield Modelling (FWMod). We employ an analytical solution to the TTI dispersion relation. Although computationally expense, it provides more flexibility compared to an acoustic anisotropic approximation. Next, we incorporate TTI kinematics in the imaging engine of JMI, Full Wavefield Migration (FWM). FWM provides the advantage in including internal multiples in imaging. Therefore, we examine the effect of internal multiples in imaging a TTI medium, which is exemplified on the 2007 BP TTI Velocity-Analysis Benchmark model. Finally, using the same model we analyse the effect of errors in the different TTI parameters on the image quality. It is shown that particularly the dip angle of the TTI medium is a sensitive parameter.