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Up/Down Separation of Seismic Images Using Hilbert Transforms
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 79th EAGE Conference and Exhibition 2017, Jun 2017, Volume 2017, p.1 - 5
Abstract
Seismic depth images obtained with reverse-time migration (RTM) can contain different kinds of artefacts due to back-scattering of wave fields at hard velocity model contrasts. I propose a simple and effective method for separating a seismic depth image into components imaged from above and components imaged from below (the sum of the source- and receiver-side slowness vectors pointing downwards vs. upwards), thereby removing RTM ghost reflection artefacts related to hard model contrasts, but also resolving partial image amplitude cancellation for reflectors illuminated and imaged from two sides. The proposed image up/down separation method is inspired by previously published wave-field up/down separation approaches. It involves combining a migrated image with an additional version of the image, obtained by applying a temporal Hilbert transform to the input data and a subsequent Hilbert transform in z on the migrated image. Compared with approaches based on up/down separation of the individual wave fields, the presented method is significantly simpler to implement, because no changes to the migration algorithm itself are required. Its computational cost, if used with RTM, is 1.5 times that of a conventional migration. The method is demonstrated on a simple synthetic and a real data example.