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Understanding Wave-equation Image-gathers – A Prerequisite for Advanced Post-processing and Velocity Model BuildingNormal access

Authors: J. Sirgue, P. Jousselin and F. Audebert
Event name: 72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010
Session: Velocity Model Building 1 (EAGE)
Publication date: 14 June 2010
DOI: 10.3997/2214-4609.201400680
Organisations: SPE, EAGE
Language: English
Info: Extended abstract, PDF ( 879.09Kb )
Price: € 20

Wave-Equation Migration has evolved towards a routine tool to generate final stack images but the computation of wave-equation image gathers has not yet spread out in the industry. Nevertheless, provided a good understanding of wave equation gathers’ typology, this prestack information proves to be useful to improve final wave-equation stack images and to build accurate velocity models. In this paper, we explore these new image-gathers, describe their behaviour in terms of true specular events as opposed to artefacts and propose solutions for the applications of these image-gathers in improved imaging and in velocity model building. We first describe what are the image-gathers produced by Wave-Equation Migration. Then we characterize the specular events and the acquisition and processing artefacts they exhibit. On analytical and synthetic image-gathers, we illustrate the artefacts linked with the acquisition truncation. Although feeding tomography with these gathers may require a sophisticated method to recover only the specular part, an adapted mute can prove to be a very efficient in a post-processing workflow. We illustrate on a real 3D subsalt dataset how the use of wave-equation image gathers significantly improves the seismic stack.

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