dc.contributor.author Lam, Nguyen Danh dc.date.accessioned 2017-09-07T22:32:44Z dc.date.issued 2017 dc.identifier.citation Lam, Nguyen Danh. SEISMIC WAVEFIELD MODELLING FROM MARINE VIBRATOR SOURCES. Master thesis, University of Oslo, 2017 dc.identifier.uri http://hdl.handle.net/10852/58224 dc.description.abstract The principles of signals from vibrators have been investigated over half a century, however such sources are rarely applied in a marine environment. The objective of this thesis is to study the modeling of the pressure field generated by oscillating vibrator plates in an acoustic medium. The methodology is based on the representation theorem applied to two states, one state relates to the real vibrator source and the other corresponds to a hypothetical state which is defined as the Green function for pressure. These states are used to model the output of a single vibrator source which consists of a pair of oscillating plates. The model relates to a faulting source where the constitutive law fails is removed. The pressure wavefield is represented everywhere inside the model by a surface integral over the Green’s function convolved with the wavefields on the plates. Based on the derived equation, we deploy an analytical solution for the rigid plates and the measurements at large source – receiver distance are approximated based on radius and the aimed frequency. In order to obtain a flat spectrum of pressure, we introduce an example of controlled plate motion of the sweep. The numerical results corresponding to our model are computed and analyzed. The surface of each plate is gridded and each grid point is assumed to be a point source. The primary wavefield from the vibrator is obtained at a given receiver location by summing the radiated signals from individual points. In the same manner, the ghost of the primary wavefield is calculated, thus the total wavefield from the vibrator at the observation point is obtained by combining the primary and its ghost. Finally, the signals created by a group of vibrator plates are considered. The directivity of the vibrator source is analyzed as well as the contribution of the ghost effect and the array effect. eng dc.language.iso eng dc.subject Vibrator source dc.subject modeling source signature dc.title SEISMIC WAVEFIELD MODELLING FROM MARINE VIBRATOR SOURCES eng dc.type Master thesis dc.date.updated 2017-09-08T22:27:30Z dc.creator.author Lam, Nguyen Danh dc.date.embargoenddate 3017-06-01 dc.rights.terms KLAUSULERING: Dokumentet er klausulert grunnet lovpålagt taushetsplikt. Tilgangskode/Access code C dc.identifier.urn URN:NBN:no-60806 dc.type.document Masteroppgave dc.rights.accessrights closedaccess dc.identifier.fulltext Fulltext https://www.duo.uio.no/bitstream/handle/10852/58224/1/thesis.pdf
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