A 4D-repeatability indicator based on similarity between shots illumination imprints

A new 4D-repeatability indicator is proposed to appraise the quality of positioning during time-lapse marine surveys. Repeatability of illumination between base and monitor surveys is assessed on selected reservoir horizons at fine discrimination scales, ranging from lines down to individual shots. Similarity between corresponding illumination imprints is evaluated from an adapted Partitioned Intensity Uniformity metric. Such repeatability indicator can be used to assess jointly source and receivers positioning during 4D towed streamers surveys and under-shoots, or only source positioning over nodes surveys. It provides a user-friendly tool to qualify the acquisition, or identify and rank preliminary re-shoots needs.