Source-Side Multi-Dimensional Deconvolution Using a Downgoing Annihilation Filter Approach

Wavefield deconvolution of seabed seismic data presents a powerful method for attenuating multiple arrivals and removing the source signature from its output reflectivity. However, although Up/Down wavefield deconvolution is widely found to be useful in practice, the accuracy of the method degrades with dipping near surface reflectivity. Furthermore, extensions to deconvolution of the downgoing wavefield to access the improved illumination of mirror migration suffer practical problems where removal of the water wave is challenging (e.g. in shallow water). An alternative approach is therefore described, in which the deconvolution proceeds by annihilation of the downgoing wavefield to produce an estimate of the isolated water wave. The resultant reflectivity includes all events below the surface source array, and is positioned at two way time. Implementation of this Annihilation Filter Deconvolution (AFD) inside a 3D Source-side Multi-Dimensional Deconvolution (S-MDD) framework allows the S-AFMDD method to work well with sparse receivers and dense shots. This avoids the problem of aliasing across widely-spaced receiver lines that is suffered by the more standard receiver-side MDD. Results from a sparse OBC dataset in the Caspian Sea show good quality, dense, reflectivity and multiple models produced by the S-AFMDD with strongly dipping near surface reflectivity.