Research And Application Of Adaptive Subtraction Methods In Surface-related Multiple Elimination

Multiple attenuation is very important in seismic wave theory and energy exploration especially in marine seismic survey. The research of surface-related multiple attenuation based on wave theory is very valuable both in theory and in practice. This research is funded by National Hi-tech Research and Development Program-Research of Inversion and Suppression for Surface-related Multiple for Marine Seismic Data.The thesis reviews the methods of multiple elimination. The surface-related multiple elimination is discussed in detail. The concept of data consistence is discussed for multiple predictions, and the adaptive iteration algorithm for multiple prediction and elimination is implemented.The paper mainly studies the adaptive subtraction for surface-related multiple. Based on least squares principle, the single channel and multichannel matching filter are formulated, resulting from second order statistic. The result is not satisfactory when primaries and multiples overlap, so the adaptive subtraction based on high-order statistic is presented, which is based on independent component analysis.The methods are tested with model and real data. Results show that both single channel and multichannel matching filter can eliminate multiples effectively, but the later is more powerful and robust when primaries and multiples overlap. Real data example almost indicates the same effect while performing better for high-order multiples. Compared with single channel matching filter, the adaptive subtraction based on high-order statistic is illustrated with model data. Results show that this method can suppress multiples effectively and primaries can almost completely recover where primaries and multiples are overlapped and nonorthogonal.At present, the filtering methods based on moveout difference are more popular for multiple suppressions in domestic geophysical practice, and methods based on seismic wave theory are not paid enough attention. Multiple eliminations based on seismic wave equation needs a further study.