Some Causes of Artefacts in 3-D Seismic Surveys and Strategies to Minimise them

Artefacts in final processed 3-D seismic data volumes are becoming more frequently reported because such dataseis are used increasingly in reservoir management projects. These artefacts commonly take the appearance of amplitude variations which are not due to geology. This leads to confusion and some loss of detectability when using data in amplitude studies, as in stratigraphic plays. They may also demonstrate structural features, usually small-scale, which again do not depict geology. In this paper, a description of some causes of such artefacts are complemented with suggestions made on methodologies for minimising, if not eliminating, their effects. Practical examples of artefacts are shown to demonstrate these effects. Guidelines are given with respect to aspects of field survey design such that these designs will have minimal effect on data interpretability. The implications of recent techniques on survey design are also investigated. In particular, the introduction of DMO in the Radon domain has considerable impact on survey designs as it allows the use of wide azimuths and irregular offset sampling. Also, certain processing-induced artefacts are described, with suggestions given as to means of reducing or eliminating them.