ROBUST MULTIPLE SUPPRESSION USING ADAPTIVE BEAMFORMING

Minimum variance unbiased (MW) beamforming is a type of multichannel f iltering which extracts coherent signals without distortion, whilst mi nimizing residual noise power. Adaptive beamforming estimates signal a nd noise characteristics as part of the extraction process. The adapti ve beamformer used here is designed from models of primary and multipl e reflection signals having parametrically specified moveout and ampli tude variation with offset (MVO and AVO). Phase variation with offset (PVO) can also be included but it is not usually justified in practice . The resulting analysis provides data for input into AVO and PVO sche mes for obtaining lithological information. Synthetic data examples il lustrate details of implementation of parametric adaptive MVU beamform ing and the response characteristics of the resultant design. Real dat a examples show that data-adaptive beamforming is more flexible and mo re effective in attenuating multiples in prestack common-midpoint seis mic data than Radon transform methods. In common with other prestack m ultichannel processes, the advantages of beamforming are shown to best effect in data with a good signal-to-noise ratio.