Multi‐angle, multi‐scale inversion of migrated seismic data: An overview

Abstract

In this paper we review the research in the DELPHI project on AVA inversion, generalized primary migration and multi-scale analysis and discuss the mutual relations. Introduction. The relation between the angle-dependent reflectivity of an interface in a target zone and the amplitude-versusoffset (AVO) effects observed in the seismic data at the Earth’s surface is complicated by many factors, as was pointed out in a classic paper by Ostrander in GEOPHYSICS in 1984. Some of these factors are ‘reflection related’ (such as thin bed tuning, reflector curvature), others ‘propagation related’ (such as geometrical spreading, transmission and/or anelastic losses) or ‘acquisition related’ (such as source/receiver directivity, geophone coupling). Amplitude-versus-angle (AVA) inversion in a target zone can only be carried out successfully when these effects are taken into account, either by forward modeling or by stepwise processing prior to AVA inversion. In our DELPHI research programme we opt for the latter approach. The setup of this paper is as follows. We start by reviewing our approach to AVA inversion for migrated reflection data, assuming that all distorting effects have been optimally eliminated. Then we address the effects of transmission loss and wavelet interference related to fine-layering and discuss how to account for these effects in migration. Finally we introduce a multi-scale model for seismic reflectors and indicate how to account for this in inversion.