Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 16 of 16 for “"Reverse Time Migration"”.
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Wave propagation in complex media, scattering theory, and application to seismic imaging
Migration is a seismic imaging method that consists of creating a representation of the Earth's subsurface structure from the recording of seismic waves. Migration is essentially equivalent to solving an inverse scattering problem in structurally complex media. Conventional migration algorithms …
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I. THE FIRST MULTI-DIMENSIONAL INVERSE-SCATTERING-SERIES INTERNAL-MULTIPLE-ELIMINATION METHOD: A NEW TOOLBOX OPTION FOR REMOVING INTERNAL MULTIPLES THAT INTERFERE WITH A PRIMARY, WITHOUT DAMAGING THE PRIMARY, AND WITHOUT ANY KNOWLEDGE OF SUBSURFACE PROPERTIES II. TESTS AND ANALYSIS FOR RESOLUTION COMPARISONS BETWEEN REVERSE TIME MIGRATION (RTM) AND THE FIRST MIGRATION METHOD THAT IS EQUALLY EFFECTIVE AT ALL FREQUENCIES AT THE TARGET
… the internal-multiple removal and (2) the first migration method that is equally effective at all frequencies at the target. The organization of the thesis is as follows. First, we provide an introduction to the new internal-multiple-elimination method. Then a similar introduction is provided for …
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Automating Pre-Stack Migration Enhancement and Image Quality Analysis
The quality of a seismic migration image strongly depends on an accurate velocity model. However, the migration velocity model often contains errors causing artifacts that degrade seismic resolution and fidelity. Here, I propose a method to enhance the seismic migration image using processes in …
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Tensorial elastodynamics and acoustodynamics for generalized seismic migration and inversion applications
… effort for such applications as elastic reverse-time migration (E-RTM) and full waveform inversion (E-FWI). However, real-life scenarios often require computing solutions for computational domains characterized by non-Cartesian geometry (e.g., free-surface topography). The majority of the …
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Seismic Imaging and Velocity Model Building in the Thrace Region, Northwestern Turkey: A Case Study
… fore-arc basin during medial Eocene to Oligocene time. The thickness of the basin-fill deposits is estimated to be up to 9 km deep. This work applied conventional seismic data processing and imaging techniques. Kirchhoff pre-stack time and depth migration are used. Tomography approach was used to …
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Multi-scale deformable layer reflection tomography and application to estimate base-salt geometry
… a migrated image. This process can be extremely time-consuming and resource intensive for a complex salt geometry and can be even more tedious in the presence of salt overhangs. The interpretation of base-salt geometry is often the most challenging part of the workflow, because salt base is …
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Modelling, Migration, and Inversion for Angle Domain Common Image Gathers
… due to the high accuracy requirements of migration and inversion algorithms. This thesis focuses on developing an new algorithm to integrate the modeling, migration, and inversion of ADCIGs. The modeling of ADCIGs is based on acoustic and elastic wave equations, and the results are …
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Continental Arc Processes in British Columbia and Earthquake Processes in Virginia: Insights from Seismic Imaging
Travel times from a refraction and wide-angle reflection seismic survey across the Coast Plutonic Complex and Stikine terrane of British Columbia were inverted to derive two dimensional P and S-wave seismic velocity models of the crust and uppermost mantle. A felsic upper crust and a felsic to …
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Seismic imaging using internal multiples and overturned waves
… structure such as salt bodies. Existing migration methods, such as Reverse Time Migration, are usually designed to image solely with primaries, and so do not make full use of energy propagating along other wave paths. In this thesis I describe several modifications to existing seismic …
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Direct Waveform Inversion Using Explicit Time-Space Causality Principle
… in the DWI is the explicit use of the wavefield time-space causality property in the inversion, which allows us to convert the global non-linear optimization problem in the FWI, without losing information, into local linear inversions that can be readily solved. The DWI is a recursive scheme …
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Inverse scattering : theory and application to the imaging of the Earth's seismic discontinuities
… a new method, which we call passive source reverse time migration (RTM), for subsurface imaging with teleseismic array data. Multi-component array data are first propagated backward by solving the elastic wave equation. After polarization separation, a modified cross-correlation imaging …
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All-optical photoacoustic and laser-ultrasonic imaging in heterogeneous tissue
… non-invasively probe and image tissues up to centimeters deep. Ultrasonic (US) imaging is the most well-known modality used to image acoustic density and velocity contrasts. US is useful for imaging overall structure in tissue, however, acoustic contrasts are relatively low in biological tissue. …
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Elastic time-reverse imaging and transmission tomography for microseismic and DAS VSP data
Wavefield migration and tomography are considered to be state-of-the-art methodologies used for subsurface geological characterization. Seismic tomography produces accurate velocity models that commonly serve as input into seismic migration algorithms that produce high-quality passive-source (e.g., …
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Efficient seismic imaging with the double plane wave data
… is the goal for exploration geophysicists. Reverse time migration (RTM), which solves the two-way wave equation, can resolve all wavefield propagation phenomena. In geologically complex regions, RTM has been proven to outperform other imaging methods in correctly revealing the subsurface …
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Efficient modeling and waveform inversion of multicomponent seismic data for anisotropic media
… which may have serious implications for elastic reverse time migration (ERTM) and elastic full-waveform inversion (EFWI). For ERTM and EFWI, another important factor to consider is the computational speed of the modeling engine because inefficient algorithms are impractical for industrial …
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Numerical modeling, suppression, and imaging of elastic wave scattering by near-surface heterogeneities
… thesis presents an approach for prestack elastic reverse time migration (RTM) to locate and image near-surface heterogeneities using the near-surface scattered waves (e.g., body to P, S, and surface waves). The approach back-projects the scattered waves until they are in phase with the incident …