3D Joint Full Wavefield Imaging of Surface and VSP Data

Abstract

Surface seismic data can provide an image over an extended area. However, due to the involved two-way travel paths – including twice propagating through a possibly unconsolidated near-surface area– the resolution usually is quite limited. Borehole-related seismic data has a broader frequency band and better quality, resulting in a higher-resolution image. The main disadvantage of VSP data is the non-uniform fold distribution, which rapidly decreases while moving away from the well. This makes the areal extent of the final image very limited. In practice, VSP and surface seismic data are processed separately and the VSP image is spliced into the surface seismic data image. This workflow does not guarantee a perfect tie of the two images. In this paper we propose to employ both surface seismic and 3D VSP data simultaneously in one imaging process, such that – at least within an area around the well location – an optimum high-resolution image is obtained and the lateral continuity and consistency is guaranteed. Furthermore, by including all multiple scattering in a closed-loop imaging process – as proposed by the full wavefield migration process – a true amplitude reflectivity image will be obtained with high resolution and maximum lateral extent.