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Title: Deterministic free surface multiple removal of marine seismic data
Author: Johnston, Rodney G. K.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2000
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This thesis presents a new method for sea surface multiple removal which includes in its solution the information at the source from the oscillating bubbles which generate the propagating wavefield. Arrays of interacting oscillating bubbles excite the earth with sound energy which is recorded as marine seismic reflection data. In the manipulation of the data to produce a detailed image of the earth's subsurface, the first task is the removal of multiple reflections related to the sea surface. The new formulation, in common with other wave-theoretical methods, requires a two-dimensional grid of receivers to record a two-dimensional grid of shots. Using the data themselves, and no information about the subsurface, all multiples are removed in a three-dimensional earth by calculating the plane wave reflection response in the frequency-wavenumber domain. Applying the plane wave concept to waves in three dimensions permits a complicated reflected wave to be decomposed into plane wave components. Each of these scattered upgoing plane wave components comprises primary and multiple reflections. The primaries result from a multiplication of an incident downgoing plane wave component with a plane wave reflection response, unique for the particular downgoing and upgoing plane wave components chosen. The multiples represent a sum of products of scattered downgoing plane wave components with plane wave reflection responses, related to the chosen downgoing and upgoing plane wave components. The result is a set of simultaneous equations whose unknowns form the three-dimensional reflection response. The wavefield from the oscillating bubbles produces the downgoing incident plane wave. There are various methods of measuring this input energy. They depend on the acquisition configuration being used, and the feasibility of placing hydrophones at certain distances from the sources of the oscillating bubbles. Consideration of the fluid dynamics of these oscillating bubbles, in isolation and together, and the wave propagation produced by them, reveals the requisite measurements to describe fully the acoustic output of the source.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available