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