Multidimensional signature deconvolution and free-surface multiple elimination of marine multicomponent ocean-bottom seismic

This paper presents a wave-equation method for multidimensional signature d econvolution (designature) and elimination of free-surface related multiple s (demultiple) in four-component (4C) ocean-bottom seismic data. The design ature/demultiple method has the following characteristics: it preserves pri mary amplitudes while attenuating free-surface related multiples; it requir es no knowledge of the sea floor-parameters and the subsurface; it requires information only of the local density and acoustic wave propagation veloci ty just above the sea floor;, it accommodates source arrays; and no informa tion (except location) of the physical source array, its volume. and its ra diation characteristics (wavelet) is required. Designature is an implicit p art of the demultiple process;, hence, the method is capable of transformin g recorded reflection data excited by any source array below the sea surfac e into free-surface demultipled data that would be recorded from a point so urce with any de-sired signature. In addition, the incident wavefield is no t subtracted from the data prior to free-surface demultiple; hence, separat ion of incident and scattered fields is not an issue as it is for most othe r free-surface demultiple schemes. The designature/demultiple algorithm can be divided into two major computat ional steps. First, a multidimensional deconvolution operator, inversely pr oportional to the time derivative of the downgoing part of the normal compo nent of the particle velocity just above the sea floor, is computed. Second , an integral equation is solved to find any component of the designatured, free-surface demultipled multicomponent. field. When the geology is horizontally layered, the designature and free-surface demultiple scheme greatly simplifies and lends itself toward implementation in the tau -p domain or frequency-wavenumber domain as deterministic decon volution of common shot gathers (or common receiver gathers when source arr ay variations are negligible).