Surface Wave Analysis and its Application to the Calculation of Converted Wave Static Corrections
| atmire.migration.oldid | 1591 | |
| dc.contributor.advisor | Ferguson, Robert J. | |
| dc.contributor.author | Roohollah, Askari | |
| dc.date.accessioned | 2013-10-03T17:56:10Z | |
| dc.date.available | 2013-11-12T08:00:20Z | |
| dc.date.issued | 2013-10-03 | |
| dc.date.submitted | 2013 | en |
| dc.description.abstract | Using surface waves, we can estimate an S-wave velocity model to address the S-wave receiver statics of converted waves. Shear wave velocity is estimated from the inversion of either phase or group velocity. I address three major problems within the realm of S-wave receiver statics and these are the problem of inversion accuracy, misinterpretation of multi-modes, and the optimization of spatial analysis windows. To improve inversion accuracy, I develop a method to simultaneously estimate the phase and group velocities of surface waves based on the generalized S transform. The method is robust and it returns accurate results. To cope with noise and dispersion in the data, I introduce two cost functions. Though my method is robust where the surface wave is highly dispersed, I find that parameterization becomes ambiguous when the surface wave is multi-modal, and so it is possible for misinterpretation of different modes of the surface wave. To address multi-modality for the estimation of the group velocity, I develop a slant stack method that is based again on the generalized S transform. To control spectral localization, I use a scaling factor in the generalized S transform. I find that a small scaling factor should be chosen for low frequency surface-waves, whereas for higher frequencies a larger scaling factor should be chosen. Finally, I determine an accurate S-wave velocity model of the near surface for use in S-wave statics estimation by optimizing the analysis spatial-window. To do this, I enlarge upon the idea of CMP Cross-Correlation of Surface Waves (CCSW). I obtain a precise estimation of a dispersion curve by limiting analysis to seismic traces that lie within a limited spatial window. I find that the optimum window length (aperture) should be close (one to one and half) to the maximum wavelength in a CMP gather. I find that, through experiment, when the aperture is optimum, a high resolution image of each mode within the dispersion curve is observable, and this avoids interpretation of modal interferences. A secondary benefit of my CCSW approach is its faster computational process than the conventional implementation. | en_US |
| dc.identifier.citation | Roohollah, A. (2013). Surface Wave Analysis and its Application to the Calculation of Converted Wave Static Corrections (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/27941 | en_US |
| dc.identifier.doi | http://dx.doi.org/10.11575/PRISM/27941 | |
| dc.identifier.uri | http://hdl.handle.net/11023/1124 | |
| dc.language.iso | eng | |
| dc.publisher.faculty | Graduate Studies | |
| dc.publisher.institution | University of Calgary | en |
| dc.publisher.place | Calgary | en |
| dc.rights | University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission. | |
| dc.subject | Geophysics | |
| dc.subject.classification | Converted wave | en_US |
| dc.subject.classification | Surface wave analysis | en_US |
| dc.subject.classification | Static correction | en_US |
| dc.subject.classification | Phase velocity | en_US |
| dc.subject.classification | Group velocity | en_US |
| dc.subject.classification | S-wave receiver statics | en_US |
| dc.subject.classification | CMP Cross-Correlation of Surface Waves (CCSW) | en_US |
| dc.subject.classification | Slant Stack Generalized S transform | en_US |
| dc.subject.classification | Generalized Stransform | en_US |
| dc.title | Surface Wave Analysis and its Application to the Calculation of Converted Wave Static Corrections | |
| dc.type | doctoral thesis | |
| thesis.degree.discipline | Geoscience | |
| thesis.degree.grantor | University of Calgary | |
| thesis.degree.name | Doctor of Philosophy (PhD) | |
| ucalgary.item.requestcopy | true |