Multiple Prediction and Subtraction from the Slowness Relations

J. Cao and G. A. McMechan
Center for Lithospheric Studies, The University of Texas at Dallas

A target oriented algorithm is proposed for the prediction of surface-related multiples，ocean bottom multiples by a process that utilizes slowness relations in common-shot gathers and common-receiver gathers. It is based on combining offsets and times of primary reflections to predict multiples by matching slownesses at source and receiver locations; all higher order multiples can be predicted by repeating the slowness matching on common-shot and common-receiver gathers alternately. An important characteristic of this proposed multiple prediction approach is that no knowledge of the subsurface velocity is required. On the other hand, the traveltimes of the primary reflections in common-shot gathers need to be provided. The subtraction involves flattening the multiple events by shifting by the predicted moveout, subtracting a local spatial average trace from each trace within a fixed time window containing the wavelet of the multiple and shifting the data back to its original time. Synthetic tests of two examples show that the proposed method predicts surface and ocean-bottom multiples very well and removes them from seismic data efficiently without changing primary reflections. A real ocean-bottom-cable data set gives convincing preliminary results.

AAPG Search and Discover Article #90087 © 2008 AAPG/SEG Student Expo, Houston, Texas