(I) The Significance of Incorporating a 3D Point Source in Inverse Scattering Series (ISS) Multiple Removal for a 1D/2D Subsurface; (II) an Alternative ISS Internal Multiple Elimination Algorithm for the First-Order Internal Multiples Having Their Downward Reflection at the Ocean Bottom
Lin, Xinglu 1989-
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Inverse scattering series (ISS) de-multiple methods do not require any subsurface information to achieve seismic processing objectives. In specific applications of the ISS de-multiple methods, the subsurface is assumed to 1D, 2D, or 3D and the dimension of the source is typically chosen to agree with the dimension of the subsurface, for example, choosing a 2D line source for a 2D subsurface. And often in deriving a 1D subsurface theory from a 2D algorithm the 2D line source is brought along into the 1D subsurface theory. However, field data are generated by a locally 3D source and realistic synthetic data need to incorporate a 3D source. The lesson is that there are times when a 1D or 2D subsurface can be a reasonable approximation, but it is always important to incorporate a 3D source to have an effective multiple predictor and removal. This dissertation describes how to incorporate a 3D source in ISS de-multiple methods for a 1D and 2D subsurface. We then evaluate the positive added value of incorporating a 3D source in the distinct 1D subsurface algorithms, using synthetic data generated by a 3D source. The second part provides an approach to address the challenge of current internal multiple attenuator. The current algorithm provides accurate time and approximate amplitude of all internal multiples. For complex circumstances, where internal multiples are often proximal to or interfering with primaries, the current ISS internal multiple attenuator plus an adaptive subtraction can fail to remove multiples without damaging primaries. This challenge demands an internal multiple eliminator, in which both time and amplitude of internal multiples can be accurately predicted. There are circumstances where it is possible to provide reliable subsurface information to transform the internal multiple attenuator into an eliminator. For example, in marine exploration, the earth properties down to and across the ocean bottom can often be estimated from a velocity analysis. With that information, the ISS internal multiple attenuator can eliminate all internal multiples having their shallowest downward reflection at the ocean bottom. The effectiveness of the proposed method is evaluated by a 1D normal incidence test.