dc.contributor.author | Ghasemi, Parisa | |
dc.date.accessioned | 2014-12-02T23:00:07Z | |
dc.date.available | 2014-12-02T23:00:07Z | |
dc.date.issued | 2014 | |
dc.identifier.citation | Ghasemi, Parisa. Total Pressure Wavefield Computation for Rough Sea-Surfaces. Master thesis, University of Oslo, 2014 | |
dc.identifier.uri | http://hdl.handle.net/10852/41700 | |
dc.description.abstract | Marine seismic data acquisition with dual-sensor streamers (Geostreamer) enables separating the total wavefield in its up-going and down-going pressure and velocity components. The separation step is largely independent of the subsurface model and sea-surface shape. As a consequence realistic rough sea-surface shapes need to be included also in modelling studies and survey design. However, modelling of seismic data with rough sea-surface is not trivial and most of the standard modelling tools are still limited to flat or smoothly varying sea-surfaces. The scope of this thesis is to investigate including realistically rough sea-surfaces in PGS modelling software Nucleus+. From Rayleigh s reciprocity theorem in acoustic media, an integral expression for computing the down-going pressure wavefield from the up-going velocity wavefield and the sea-surface reflectivity is derived. The sea-surface reflectivity is computed based on Helmholtz-Kirchhoff integral using a free-surface boundary condition (Orji et al., 2011) and the up-going vertical particle velocity wavefield is computed as subsurface modelling from Nucleus+. The computation accuracy of the derived down-going pressure wavefield depends mainly on the numerical solution of the integrals and is proved by comparing with the total pressure field from Nucleus+ using smooth and flat sea-surfaces. Edge effects in the calculated down-going pressure wavefield are partly suppressed by using a cosine tapered window. Finally, the modelling is tested on a realistically rough sea-surface derived from a Pierson-Moskowitz (PM) spectrum. The total pressure field is computed by adding the computed down-going pressure wavefield including the effects of the realistic sea-surface to the modelled up-going pressure wavefield from Nucleus+. | eng |
dc.language.iso | eng | |
dc.subject | Modeling | |
dc.subject | rough | |
dc.subject | sea | |
dc.subject | surface | |
dc.subject | Downgoing | |
dc.subject | wavefield | |
dc.subject | computation | |
dc.subject | Pierson | |
dc.subject | Moskowitz | |
dc.subject | sea | |
dc.subject | surface | |
dc.title | Total Pressure Wavefield Computation for Rough Sea-Surfaces | eng |
dc.type | Master thesis | |
dc.date.updated | 2014-12-02T23:00:07Z | |
dc.creator.author | Ghasemi, Parisa | |
dc.identifier.urn | URN:NBN:no-46159 | |
dc.type.document | Masteroppgave | |
dc.identifier.fulltext | Fulltext https://www.duo.uio.no/bitstream/handle/10852/41700/1/Parisa_Ghasemi_MasterThesis.pdf | |