Tesis sobre el tema "Seismic"
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Marks, Samantha Georgina. "Seismic wave attenuation from vertical seismic profiles". Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384872.
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Vice, President Research Office of the. "Seismic Shift". Office of the Vice President Research, The University of British Columbia, 2006. http://hdl.handle.net/2429/2662.
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Tatelman, Anna. "Seismic Communication". ScholarWorks@UNO, 2019. https://scholarworks.uno.edu/td/2707.
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Adiya, Munkhsaikhan. "Seismic activity near Ulannbaatar : implication for seismic hazard assessment". Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAH007/document.
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On observe depuis 2005 une sismicité intense à 10 km d'Oulan Bator ce qui a permis d'identifier une faille active, Emeelt, sur le terrain. Après le calcule d'un modèle de vitesse 3D, j'ai appliqué la tomographie double différence pour obtenir une localisation précise des séismes. Ils marquent au moins trois branches parallèles orientées N147° comme la faille vue en surface. L'activité sur la faille principale d'Emeelt (MEF) s’étend sur 15 km, les branches Ouest et Est, moins actives, sur 10 km. La profondeur de l'activité s'étend entre 4 et 15 km. L'activité sismique semble concentrée à l'intersection avec des failles Mésozoïques et les contrastes Vs/Vs suggèrent la présence de fluides. Les 10 essaims identifiés montrent une activité croissante et une migration spatiale avec le temps. Le calcul de 2 scénarios possibles, un M ~ 6.4 et un M ~ 7, indique un important impact sur la ville d'Oulan Bator, avec une intensité minimum de VIII et localement IX pour M=6.4 et X pour M=7We observe since 2005 a high seismic activity at 10 km from Ulaanbaatar that allowed us to identify a new active fault, Emeelt, in the field. After computing a 3D velocity model, I applied Double-Difference tomography to obtain a precise localization of earthquakes. They trace at least three parallel branches oriented N147° like the fault seen at surface. The seismic activity on the Main Emeelt Fault (MEF) is along at least 15 km, on the West and East branches, less active, along 10 km. The depth of the seismicity extends between 4 and 15 km. The activity seems concentrated at the intersection with Mesozoic faults and Vp/Vs contrast suggests the presence of fluids. The 10 swarms identified show an increasing activity and a spatial migration with time. The calculation of 2 possible scenarios, one M ~ 6.4 and one M ~ 7, shows an important impact on Ulaanbaatar, with a minimum intensity of VIII and IX for M=6.4 and X for M=7
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Raji, Wasiu. "Seismic and petro-physical studies on seismic wave attenuation". Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/7617/.
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Anelasticity and inhomogeneity in the Earth decreases the energy and modifies the frequency of seismic waves as they travel through the Earth. This phenomenon is known as seismic attenuation. The associated physical process leads to amplitude diminution, waveform distortion and phase delay. The level of attenuation a wave experiences depends on the degree of anelasticity and the scale of inhomgeneity in the rocks it passes through. Therefore, attenuation is sensitive to the presence of fluids, degree of saturation, porosity, fault, pressure, and the mineral content of the rocks. The work presented in this thesis covers attenuation measurements in seismic data; estimation of P- and S-wave attenuation in recorded well logs; attenuation analysis for pore fluid determination; and attenuation compensation in seismic data. Where applicable, a set of 3D seismic data or well logs recorded in the Gullfaks field, North Sea, Norway, is used to test the methods developed in the thesis. A new method for determining attenuation in reflection seismic data is presented. The inversion process comprises two key stages: computation of centroid frequency for the seismic signal corresponding to the top and base of the layer being investigated, using variable window length and fast Fourier transform; and estimation of the difference in centroid frequency and traveltime for the paired seismic signals. The use of a shape factor in the mathematical model allows several wavelet shapes to be used to represent a real seismic signal. When applied to synthetic data, results show that the method can provide reliable estimates of attenuation using any of the wavelet shapes commonly assumed for a real seismic signal. Tested against two published methods of quality factor (Q) measurement, the new method shows less sensitivity to interference from noise and change of frequency bandwidth. The method is also applied to seismic data recorded in the Gullfaks field. The trace length is divided into four intervals: AB, BC, CD, and DE. The mean attenuation (1/Q_m) calculated in intervals AB, BC, CD, and DE are 0.0196, 0.0573, 0.0389, and 0.0220, respectively. Results of attenuation measurements using the new method and the classical spectral ratio method (Bath 1974, Spencer et al, 1982) are in close agreement, and they show that interval BC and AB have the highest and lowest value of attenuation, respectively. One of the applications of Q measured in seismic records is its usage for attenuation compensation. To compensate for the effects of attenuation in recorded seismograms, I propose a Q-compensation algorithm using a recursive inverse Q-filtering scheme. The time varying inverse Q-filter has a Fourier integral representation in which the directions of the up-going and down-going waves are reversed. To overcome the instability problem of conventional inverse Q-filters, wave numbers are replaced with slownesses, and the compensation scheme is applied in a layer-by-layer recursive manner. When tested with synthetic and field seismograms, results show that the algorithm is appropriate for correcting energy dissipation and waveform distortion caused by attenuation. In comparison with the original seismograms, the Q-compensated seismograms show higher frequencies and amplitudes, and better resolved images of subsurface reflectors. Compressional and shear wave inverse quality factors (Q_P^(-1) and Q_S^(-1)) are estimated in the rocks penetrated by well A-10 of the Gullfaks field. The results indicate that the P-wave inverse quality factor is generally higher in hydrocarbon-saturated rocks than in brine-saturated rocks, but the S-wave inverse quality factor does not show a dependence on fluid content. The range of the ratio of Q_P^(-1) to Q_S^(-1) measured in gas, water and oil-saturated sands are 0.56 – 0.78, 0.39 – 0.55, and 0.35 – 0.41, respectively. A cross analysis of the ratio of P-wave to S-wave inverse quality factors, (Q_P^(-1))/(Q_S^(-1) ), with the ratio of P-wave to S-wave velocities, V_P/V_S , clearly distinguishes gas sand from water sand, and water sand from oil sand. Gas sand is characterised by the highest (Q_P^(-1))/(Q_S^(-1) ) and the lowest V_P/V_S ; oil sand is characterised by the lowest (Q_P^(-1))/(Q_S^(-1) ) and the highest V_P/V_S ; and water sand is characterized by the V_P/V_S and (Q_P^(-1))/(Q_S^(-1) ) values between those of the gas and oil sands. The signatures of the bulk modulus, Lame’s first parameter, and the compressional modulus (a hybrid of bulk and shear modulus) show sensitivities to both the pore fluid and rock mineral matrix. These moduli provided a preliminary identification for rock intervals saturated with different fluids. Finally, the possibility of using attenuation measured in seismic data to monitor saturation in hydrocarbon reservoirs is studied using synthetic time-lapse seismograms, and a theoretical rock physics forward modelling approach. The theory of modulus-frequency-dispersion is applied to compute a theoretical curve that describes the dynamic effects of saturation on attenuation. The attenuation measured in synthetic time-lapse seismograms is input to the theoretical curve to invert the saturation that gave rise to the attenuation. Findings from the study show that attenuation measured in recorded seismograms can be used to monitor reservoir saturation, if a relationship between seismogram-derived attenuation and saturation is known. The study also shows that attenuation depends on other material properties of rocks. For the case studied, at a saturation of 0.7, a 10% reduction in porosity caused a 5.9% rise in attenuation, while a 10% reduction in the bulk modulus of the saturating fluids caused an 11% reduction in attenuation.
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Zhang, Qie Sandvol Eric Alan. "Seismic tomography and anisotropy: studies of intraplate seismic zones". Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6855.
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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 24, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Eric Sandvol. Vita. Includes bibliographical references.
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Qian, Zhongping. "Analysis of seismic anisotropy in 3D multi-component seismic data". Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/3515.
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The importance of seismic anisotropy has been recognized by the oil industry since its first observation in hydrocarbon reservoirs in 1986, and the application of seismic anisotropy to solve geophysical problems has been keenly pursued since then. However, a lot of problems remain, which have limited the applications of the technology. Nowadays, more and more 3D multi-component seismic data with wide-azimuth are becoming available. These have provided more opportunities for the study of seismic anisotropy. My thesis has focused on the study of using seismic anisotropy in 3D multi-component seismic data to characterize subsurface fractures, improve converted wave imaging and detect fluid content in fractured reservoirs, all of which are important for fractured reservoir exploration and monitoring. For the use of seismic anisotropy to characterize subsurface fracture systems, equivalent medium theories have established the link between seismic anisotropy and fracture properties. The numerical modelling in the thesis reveals that the amplitudes and interval travel-time of the radial component of PS converted waves can be used to derive fracture properties through elliptical fitting similar to P-waves. However, sufficient offset coverage is required for either the P- or PS-wave to reveal the features of elliptical variation with azimuth. Compared with numerical modelling, seismic physical modelling provides additional insights into the azimuthal variation of P and PS-wave attributes and their links with fracture properties. Analysis of the seismic physical model data in the thesis shows that the ratio of the offset to the depth of a target layer (offset-depth ratio), is a key parameter controlling the choice of suitable attributes and methods for fracture analysis. Data with a small offset-depth ratio from 0.7 to 1.0 may be more suitable for amplitude analysis; whilst the use of travel time or velocity analysis requires a large offset-depth ratio above 1.0, which can help in reducing the effect of the acquisition footprint and structural imprint on the results. Multi-component seismic data is often heavily contaminated with noise, which will limit its application potential in seismic anisotropy analysis. A new method to reduce noise in 3D multi-component seismic data has been developed and has proved to be very helpful in improving data quality. The method can automatically recognize and eliminate strong noise in 3D converted wave seismic data with little interference to useful reflection signals. Component rotation is normally a routine procedure in 3D multi-component seismic analysis. However, this study shows that incorrect rotations may occur for certain acquisition geometry and can lead to errors in shear-wave splitting analysis. A quality control method has been developed to ensure this procedure is correctly carried out. The presence of seismic anisotropy can affect the quality of seismic imaging, but the study has shown that the magnitude of the effects depends on the data type and target depth. The effects of VTI anisotropy (transverse isotropy with a vertical symmetry axis) on P-wave images are much weaker than those on PS-wave images. Anisotropic effects decrease with depth for the P- and PS-waves. The real data example shows that the overall image quality of PS-waves processed by pre-stack time migration has been improved when VTI anisotropy has been taken into account. The improvements are mainly in the upper part of the section. Monitoring fluid distribution is an important task in producing reservoirs. A synthetic study based on a multi-scale rock-physics model shows that it is possible to use seismic anisotropy to derive viscosity information in a HTI medium (transverse isotropy with a horizontal symmetry axis). The numerical modelling demonstrates the effects of fluid viscosity on medium elastic properties and seismic reflectivity, as well as the possibility of using them to discriminate between oil and water saturation. Analysis of real data reveals that it is hard to use the P-wave to discriminate oil-water saturation. However, characteristic shear-wave splitting behaviour due to pore pressure changes demonstrates the potential for discriminating between oil and water saturation in fractured reservoirs.
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Yuan, Jianxin. "Analysis of four-component seafloor seismic data for seismic anisotropy". Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/11663.
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Interest in converted waves (C-waves) has been growing significantly in recent yeas due to the advent of four-component (4C) ocean-bottom-cable (OBC) seismic recordings. This has changed the way geophysicists obtain fluid and lithology information about hydrocarbon reservoirs through joint P- and converted-wave analysis. Since 4C OBC surveys use conventional air-gun sources, which generate P-waves only, the shear-waves recorded by the 4C sensors on the ocean bottom are mode-converted shear-waves. The main focus of this thesis is to find ways to process and understand these mode-converted shear-waves in the presence of seismic anisotropy which is common in marine sediments. To this end, I examine and model the data characteristics of 4C seismic data, review the basic theory of converted-wave processing, develop new kinematic theories for converted-waves propagating in anisotropic, inhomogeneous media, and apply these new methods to field 4C data. I focus on two types of anisotropy: transverse isotropy with either a vertical (TIV) or horizontal (TIH) axis of symmetry. As an emerging technology, the characteristics of 4C seismic data have not been fully understood, and there are many acquisition related problems yet to be solved. The characteristics of 4C seafloor data have been studied by field data analysis and by synthetic modelling. I have found: 1) the water-column reverberations in the vertical geophone are much weaker than those in the hydrophone, because of the different sensor responses to the source- and receiver-side multiples; 2) the presence of a low shear-wave velocity gradient in the seabed prohibits P-to-S conversion, and this implies that most shear-waves recorded in 4C data are converted at deep reflector; 3) due to current sensor design, there is a shear-wave energy leakage from the inline horizontal geophone to the vertical geophone, resulting in geophone coupling problem. I have also studied the problem of sensor orientation and presented geophone orientation algorithms for both gimballed and non-gimballed geophone systems.
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Nishiyama, Minehiro. "Seismic Response and Seismic Design of Prestressed Concrete Building Structures". Kyoto University, 1993. http://hdl.handle.net/2433/74644.
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Lee, Changhyun. "Seismic Imaging using Image Point Transform for Borehole Seismic data". 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/66203.
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Kyoto University (京都大学)0048
新制・課程博士
博士(工学)
甲第14138号
工博第2972号
新制||工||1441(附属図書館)
26444
UT51-2008-N455
京都大学大学院工学研究科社会基盤工学専攻
(主査)教授 松岡 俊文, 教授 石田 毅, 教授 三ケ田 均
学位規則第4条第1項該当
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Carter, Andrew James. "Seismic waves from surface seismic reflection surveys : an exploration tool?" Thesis, University of Leeds, 2003. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633653.
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Harrigan, Edward. "Seismic event tracking". Thesis, University of Strathclyde, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267506.
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Lo, Tien-when. "Seismic borehole tomography". Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/54325.
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Artman, Bradley. "Passive seismic imaging /". May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Vahdat, Kamran. "Seismic risk management". Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/9180/.
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Seismic risk management is a problem of many dimensions, involving multiple inputs, interactions within risk factors, criteria, alternatives and stakeholders. The deployment of this process is inherently fraught with the issues of complexity, ambiguity and uncertainty, posing extra challenges in the assessment, modelling and management stages. The complexity of earthquake impacts and the uncertain nature of information necessitate the establishment of a systematic approach to address the risk of many effects of seismic events in a reliable and realistic way. To fulfill this need, the study applies a systematic approach to the assessment and management of seismic risk and uses an integrated risk structure. The fuzzy set theory was used as a formal mathematical basis to handle uncertainties involved within risk parameters. Throughout the process, the potential impacts of an earthquake as the basic criteria for risk assessment were identified and relations between them were accommodated through a hierarchical structure. The various impacts of an earthquake are then aggregated through a composite fuzzy seismic risk index (FSRi) to screen and prioritize the retrofitting of a group of school buildings in Iran. Given the imprecise data which is the prime challenge for development of any risk model, the proposed model demonstrates a more reliable and robust methodology to handle vague and imprecise information. The significant feature of the model is its transparency and flexibility in aggregating, tracing and monitoring the risk impacts. The novelty of this study is that it serves as the first attempt of the process of a knowledge base risk-informed system for ranking and screening the retrofitting group of school buildings. The model is capable of integrating various forms of knowledge (quantitative and qualitative information) extracted from different sources (facts, algorithms, standards and experience). The outcomes of the research collectively demonstrate that the proposed system supports seismic risk management processes effectively and efficiently.
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Rivera, Cruz Ivan. "An evaluation of seismic flat dilatometer and lateral stress seismic piezocone". Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/3890.
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The flat dilatometer (DMT) and piezocone penetration (CPTU) tests are likely to be among the most
widely used in situ testing methods for soil characterization and indirect determination of geotechnical
design parameters such as: strength, stiffness, permeability and compressibility. The flat dilatometer has
proved to be a reliable, robust and adaptable tool, and the data obtained with this instrument is very
repeatable, and easy to reduce and process. Furthermore, the addition of a seismic module to the standard
flat dilatometer (SDMT) to measure the shear wave velocity (Vs) significantly complements the set of
data typically obtained with a standard DMT test. Nonetheless, the experience in interpreting the
combination between Vs and DMT data is fairly limited due to the recent introduction of the SDMT for
commercial applications. Additionally, the estimation of the coefficient of earth pressure at rest (K₀) has
been the most important application of the DMT since its introduction. However, a potential weakness of
the DMT is that the derivation of K₀ is based upon empirical correlations developed some time ago and
neither improvement work nor upgrade of these approaches has been performed in the last 10 years.
Throughout the years several additional sensors have been developed in order to supplement the data
collected with the CPTU test. Among the wide variety of sensor developed, the lateral stress module
mounted behind a piezocone represents a promising tool for estimation of in situ lateral stress conditions
from the interpretation of lateral stress penetration data. However, the popularity of the so called lateral
stress cone has declined over the years due to constraints in both the instrumentation and the
interpretation of measured data. Also, the application of this instrument remains limited to specific soils
conditions and specific projects. However, the valuable experience gained throughout the years in the
development and application of several lateral stress cones in combination with developments in
electronics and understanding of soil behaviour allow the improvement of this type of technology.
This thesis presents the results of a comprehensive laboratory and field testing programs performed by the
author at several research sites located in the Lower Mainland of BC, undertaken in order to assess the
performance of the seismic flat dilatometer and lateral stress seismic piezocone (LSSCPTU), built and
develop at UBC. Firstly, the analysis of field measurements with the SDMT collected at several sites have
demonstrated the potential for an improved soil characterization through the combination of DMT
parameters and the small strain shear modulus (G₀). Additionally the usefulness of the DMT-C closing
pressure for soil identification is shown. On the basis of several relationships identified from this data, a
new soil type behaviour system based upon SDMT measurements is proposed. Furthermore, empirical
correlations based upon fairly large and updated databases have been developed to estimate K₀ and Vs
values from DMT parameters.
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Olivier, Gerrit. "Seismic imaging and monitoring in mines with ambient seismic noise correlations". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAU018/document.
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Cette thèse s'intéresse au développement des méthodes d'auscultation sismique passive pour l'imagerie et la surveillance des mines profondes. Les résultats marquants sont 1/ la possibilité d'imager en profondeur les structures géologiques d'intérêt et 2/ la possibilité de suivre dans le temps les propriétés mécaniques des roches qui subissent les sollicitation associés à l'exploitation minière. Ce travail ouvre des perspectives quant à l'amélioration de la sécurité dans les mines profondesThis work focus on using passive noise-based seismic methods to image and monitor the rock mass in underground mines. The main results show that it is possible to gain benefit from the diffuse ambient seismic field in mines to 1/ image the rock mass and 2/ monitor its mechanical property changes over time. This work opens a way to improve safety in deep underground mines
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Maercklin, Nils. "Seismic structure of the Arava Fault, Dead Sea Transform". Phd thesis, [S.l.] : [s.n.], 2004. http://pub.ub.uni-potsdam.de/2004/0046/marcklin.pdf.
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Gislason, Gardar. "Effect of Petrophysical Parameters on Seismic Waveform Signatures : Review of Theory with Case Study from Frigg Delta Oil Field, Norway". Thesis, Uppsala universitet, Geofysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-303793.
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Conventional AVO analysis has been used for the past 4 decades to aid in locating oil and gas reservoirs for extraction. It is, however, not possible to use it to acquire information on the porosity of the rock, the fluid saturation or other important petrophysical parameters. In this thesis, I study the effects of attenuation on seismic waveform signatures, due to wave induced fluid-flow. In the first part of the thesis, 2 models were used to synthetically model the attenuation caused by the wave induced fluid-flow: White's model and the double-porosity dual-permeability (DPDP) model. The parameters used for modeling were both synthetic and acquired from real well data of a known oil field off the coast of Norway. White's model was found to model relatively high attenuation (5%) for intermediately consolidated gas reservoirs while oil saturated intermediately consolidated reservoirs showed such low attenuation (0.3%) that it is easy to say that for the real-world situation it would not be detected. The DPDP model seemed to be able to better describe the attenuation and gave attenuations up to 10% for an intermediately consolidated oil reservoir, but due to lack of parameters from well data it was not sufficiently able to model the real-world situation. The synthetic data, however, show interesting characteristics and it is therefore recommended that more and detailed well parameters be acquired if the research should continue. For the second part, Svenska Petroleum Exploration AB and Det Norske Oljeselskap ASA provided stacked seismic data that were spectrally analyzed for hints of attenuation variation with frequency (using Fourier Transform and Complex Spectral Decomposition). Twelve locations, on the stacked seismic cube, were analyzed; six oil saturated; and six (assumed) water saturated. At each location, a main trace was selected along with the two nearby traces on each side of it (five in total). The Complex Spectral Decomposition method seemed unable to correctly break down the stacked section's signal, which is why Fourier Transform was used for further analysis. The frequency analysis showed a peak at ~30 Hz for both oil and water saturated reservoirs which seems like a characteristic frequency of the source, but that was unfortunately not confirmed and not enough time was available to test the assumption. The Fourier transform seems to show some difference between oil and water saturated traces, but that could well be because of lithological differences and not the pore fluid. It is therefore recommended, if research is to be continued, that 4D seismic data is used to analyze the same location with respect to time. It is also recommended that pre-stack or shot data be used as information is lost in stacked data.Konventionell AVO-analys har använts under fyra deceniär som ett hjälpmedel för att finna olje- och gasreserver, men tekniken kan även användas för att erhålla information om bergets porositet, vätskemättnaden och andra viktiga petrofysiska parametrar. I denna avhandlingen har jag studerat hur våginducerat vätskeflöde påverkar dämpningen av den seismiska vågformssignaturen. I den första delen av avhandlingen användes två metoder för att syntetisk modellera dämpning orsakad av våginducerat vätskeflöde: "White's modell" och "double-porosity dual-permeability (DPDP) modellen". Både syntetiska parametrar och verkliga parametrar från borrhålsdata från ett känt norskt oljefält användes vid modelleringen. White's modell visade sig modellera relativt kraftig dämpning (5%) för medelstarkt konsoliderade gasreservoarer medan för oljereservoarer med motsvaranda konsolidering dämpningen var så låg (0.3%) att det är uppenbart att i en verklig situation skulle dämpningen inte vara mätbar. DPDP modelleringen verkar vara bättre på att beskriva dämpningen och gav dämpningar upp till 10% för en medelstarkt konsoliderad oljereservoar. Brist på parametrar från borrhålsdata gjorde att det inte var möjligt att på ett tillfredställande sätt modellera en verklig situation.Dock visade syntetisk data intressant karaktäristik och det rekommenderas därför att mer och detaljerade borrhålsparametrar mäts om ytterligare forskning om detta ska genomföras. För den andra delen av avhandlingen har Svenska Petroleum Exploration AB och Det Norske Oljeselskap ASA bidragit med stackad seismisk data som även var spectralanalyserad för indikationer på frekvensberoende dämpningsvariationer (utfört med fouriertransform och komplex spectraldekomposition). Tolv områden på den stackade kuben analyserades; sex oljemättade och sex som antogs vara vattenmättade. I varje område valdes en huvudtracé och de två närmaste tracéerna på vardera sida (totalt fem tracéer). Metoden med komplex spectraldekomposition klarade inte att analysera signalen från den stackade sektionen, varför fouriertransform användes för vidare analys. Frekvensanalysen gav en topp vid ~30 Hz för både olje- och vattenmättade reservoarer vilket tycks vara en karaktäristisk frekvens för källan. Detta kunde tyvärr inte bekräftas och tiden räckte inte till för att testa antagandet. Fouriertransformen tycks visa en viss skillnad mellan olje- och vattenmättade tracéer, men det kan också bero på skillnad i litologin snarare än porvätskan. Där för rekommenderas vid fortsättning på denna forskning att 4D seismisk data används för att analysera samma område men med data från olika tidpunkter. Det rekommenderas även att ostackad eller råa skott-data används eftersom väsentlig information kan försvinna när data stackas.
Advisor present: Dr. Chris Juhlin
Examiner: Dr. Milovan Urosevic
Opponent: Álvaro Polín Tornero
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Amini, Hamed. "A pragmatic approach to simulator-to-seismic modelling for 4D seismic interpretation". Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2756.
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Luis, Alberto Bedriñana Mera. "SEISMIC PERFORMANCE AND SEISMIC DESIGN OF DAMAGE-CONTROLLED PRESTRESSED CONCRETE BUILDING STRUCTURES". Kyoto University, 2018. http://hdl.handle.net/2433/235084.
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Zhang, Yaohui. "Common conversion point stacking for P-SV converted waves /". Access abstract and link to full text, 1992. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/9218599.
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Buland, Arild. "Bayesian Seismic AVO Inversion". Doctoral thesis, Norwegian University of Science and Technology, Department of Mathematical Sciences, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2005.
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Seismic analysis is a key element in successful exploration and production of natural resources. During the last decades, seismic methodology has had a significant progress with respect to both acquisition, processing and analysis. Despite all the new tec hnology, the uncertainty related to seismic analysis is still large, and even worse, the uncertainty is often not systematically assessed.
In this thesis, the uncertainty aspect of seismic amplitude versus offset (AVO) in version is assessed using a Bayesian approach to inversion. The main objective is to estimate elastic material parameters with associated uncertainty from large seismic data sets, but the in versionproblem also includes estimation of seismic wavelets and the noise level. State of the art statistical methodology is applied to attack these current and crucial geophysical problems. The core part of the work is presented in four separate papers written for geophysical journals, constituting Chapter 2 through 5 in this thesis. Each of the papers is self-contained, with exception of the references which are placed in a separate bibliography chapter.
Paper I, II and III: copyright SEG Paper III: copyright EAGE
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Miller, Susan L. M. "Multicomponent seismic data interpretation". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq20841.pdf.
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Chironi, Caterina. "Sub-basalt seismic imaging". Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410001.
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Butterfield, Katherine J. "Seismic Liquefaction Trigger Mechanisms". Thesis, University of Canterbury. Civil Engineering, 2004. http://hdl.handle.net/10092/1179.
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Three possible mechanisms for the onset of excess pore water pressure generation due to seismic excitation of saturated soil are investigated using downhole array data from sixteen real earthquakes. The downhole data are used to synthesize both stress and strain at various depths within the ground. Stresses, strains and dissipated energy are then investigated as potential liquefaction trigger mechanisms. The hypothesis that the shear strain threshold is a liquefaction trigger mechanism is strongly supported by the results presented here. In all but one case the shear strain threshold accurately predicts the time of pore pressure rise for real earthquakes in the field. Additionally, the onset of energy dissipation is found to signal the initial rise in measured excess pore pressure remarkably accurately. The results suggest a fundamental link between Nemat-Nasser and Shokooh's pore pressure - dissipated energy.density relationship (1979) and Mindlin and Deresiewicz's (1953) theoretical strain threshold. Mindlin and Deresiewicz's work (1953) defined a theoretical strain threshold as the mechanism for the onset of gross sliding, and 'its associated energy dissipation'. Therefore the onset of energy dissipation constitutes a second, independent verification of the strain threshold hypothesis. The relationship between stress invariants and pore pressure increase is less clear. To date there does not appear to be an acceptable theory that describes a trigger mechanism in terms of stress alone.
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Dougherty, Martin Eugene. "Ocean bottom seismic scattering". Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/52938.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, and Woods Hole Oceanographic Institution, 1990.GRSN 589503
Includes bibliographical references (p. 299-301).
by Martin Eugene Dougherty.
Ph.D.
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Ballantyne, Brant Francis 1974. "Seismic isolation of bridges". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/80632.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2000.Includes bibliographical references (leaves 41-42).
by Brant Francis Ballantyne.
M.Eng.
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Cilingir, Ulas. "Seismic response of tunnels". Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608467.
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Phansalkar, Nachiket S. "Seismic Substructure Design Workbook". University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1220554481.
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Lu, Xiaolin. "Seismic ray impedance inversion". Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6085.
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This thesis investigates a prestack seismic inversion scheme implemented in the ray parameter domain. Conventionally, most prestack seismic inversion methods are performed in the incidence angle domain. However, inversion using the concept of ray impedance, as it honours ray path variation following the elastic parameter variation according to Snell’s law, shows the capacity to discriminate different lithologies if compared to conventional elastic impedance inversion. The procedure starts with data transformation into the ray-parameter domain and then implements the ray impedance inversion along constant ray-parameter profiles. With different constant-ray-parameter profiles, mixed-phase wavelets are initially estimated based on the high-order statistics of the data and further refined after a proper well-to-seismic tie. With the estimated wavelets ready, a Cauchy inversion method is used to invert for seismic reflectivity sequences, aiming at recovering seismic reflectivity sequences for blocky impedance inversion. The impedance inversion from reflectivity sequences adopts a standard generalised linear inversion scheme, whose results are utilised to identify rock properties and facilitate quantitative interpretation. It has also been demonstrated that we can further invert elastic parameters from ray impedance values, without eliminating an extra density term or introducing a Gardner’s relation to absorb this term. Ray impedance inversion is extended to P-S converted waves by introducing the definition of converted-wave ray impedance. This quantity shows some advantages in connecting prestack converted wave data with well logs, if compared with the shearwave elastic impedance derived from the Aki and Richards approximation to the Zoeppritz equations. An analysis of P-P and P-S wave data under the framework of ray impedance is conducted through a real multicomponent dataset, which can reduce the uncertainty in lithology identification.Inversion is the key method in generating those examples throughout the entire thesis as we believe it can render robust solutions to geophysical problems. Apart from the reflectivity sequence, ray impedance and elastic parameter inversion mentioned above, inversion methods are also adopted in transforming the prestack data from the offset domain to the ray-parameter domain, mixed-phase wavelet estimation, as well as the registration of P-P and P-S waves for the joint analysis. The ray impedance inversion methods are successfully applied to different types of datasets. In each individual step to achieving the ray impedance inversion, advantages, disadvantages as well as limitations of the algorithms adopted are detailed. As a conclusion, the ray impedance related analyses demonstrated in this thesis are highly competent compared with the classical elastic impedance methods and the author would like to recommend it for a wider application.
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Nurhandoko, Bagus Endar Bachtiar. "Fresnel zone seismic tomography". Kyoto University, 2000. http://hdl.handle.net/2433/180954.
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Savage, Brian Kirk Gurnis Michael. "Regional seismic wavefield propagation /". Diss., Pasadena, Calif. : California Institute of Technology, 2004. http://resolver.caltech.edu/CaltechETD:etd-05262004-100247.
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Monterroso, Juárez David Aníbal. "Statistical Seismology Studies in Central America : b-value, seismic hazard and seismic quiescence". Doctoral thesis, Uppsala University, Department of Earth Sciences, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3613.
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The present thesis collects results of research applying theory and methods of statistical seismology to the seismicity of Central America, a region with a complex tectonic setting controlled by the interaction of four major plates, namely the Caribbean, Cocos, Nazca and North American plates.
Three different earthquake catalogues were used for studies focused on stress in a tectonic volume, seismic hazard maps and seismicity patterns (precursors), covering the region 94ºW to 81ºW and 5ºN to 20ºN.
Variations in the b-value, the parameter in Gutenberg & Richter’s equation LogN=a-bM, as a function of depth in the subduction zone were investigated. High b-values were identified in the upper part of the slab at depths of 80-110km beneath Guatemala-El Salvador and at depths 130-170km beneath Nicaragua. These anomalies may be related to the generation of volcanism occurring above them. Time dependence of the b-value was also studied. Five case studies were selected (events with MS ≥7.2) for a detailed analysis. In three out of five cases, it was possible to link b-value minima to the time of occurrence of corresponding large events.
Seismic quiescence was mapped as a function of time and space by a griding technique. The characteristics of the quiescence were calculated using the statistics Z and ß and for Time Window lengths between 1 and 5 years. Five positive anomalies were found, which can be associated with large earthquakes (MS≥7.2).
Finally, a Monte Carlo approach was utilized to evaluate the ground motion hazard and its uncertainties in northern Central America. A set of new seismic hazard maps exhibiting probabilistic values of peak ground acceleration (PGA) with 50%, 10%, and 5% probabilities of exceedance (PE) in 50 years is presented for a large area of northern Central America, including El Salvador and Guatemala.
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Valenzuela-Beltrán, Federico, Sonia Ruiz, Alfredo Reyes-Salazar y J. Gaxiola-Camacho. "On the Seismic Design of Structures with Tilting Located within a Seismic Region". MDPI AG, 2017. http://hdl.handle.net/10150/626403.
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A reliability-based criterion to estimate strength amplification factors for buildings with asymmetric yielding located within a seismic region presenting different soil conditions is proposed and applied. The approach involves the calculation of the mean annual rate of exceedance of structural demands of systems with different levels of asymmetric yielding. Two simplified mathematical expressions are developed considering different soil conditions of the valley of Mexico. The mathematical expressions depend on the ductility of the structural systems, their level of asymmetric yielding, their fundamental vibration period and the dominant period of the soil. In addition, the proposed expressions are compared with that recommended by the current Mexico City Building Code (MCBC). Since the expressions are developed with the help of simplified structural systems, the validity of such expressions is corroborated by comparing the expected ductility demand of multi-degree of freedom (MDOF) structural systems with respect to that of their equivalent simplified systems. Both structural representations are associated with a given annual rate of exceedance value of an engineering demand parameter. The expressions proposed in this study will be incorporated in the new version of the MCBC.
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Duggan, Tim. "Seismic studies and travel time calculations for the Lachlan Fold Belt Seismic Array /". Adelaide, 1999. http://web4.library.adelaide.edu.au/theses/09SB/09sbd866.pdf.
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Gloria, Lopez Juan Carlos. "Integrating AVO, Seismic Inversion, and Rock Physics in Agua Fría 3D Seismic Cube". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26114.
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Ten exploratory wells have been drilled in the Agua Fría area, led by amplitude anomalies and structural highs. Five of them resulted in dry wells and the other five in gas and oil discoveries. In some of these wells, water sands respond seismically as amplitude anomalies. On the other hand, some oil and gas sands are not easily recognizable from post-stack seismic data. Bright spots are also observed in the study area.Seismic interpretation can be uncertain if no geology is related to elastic response of the subsurface rocks. The purpose of this thesis is to integrate diagenesis data from log and core data, rock physics models, AVO analysis and seismic inversion information to characterize the Agua Fría 3D seismic cube. Mechanical compaction and sorting are the main factors affecting the porosity trend in the selected wells according to the rock physics modeling. AVO class III are the main class present in the study area. However, these responses can be related to brine, oil or gas sands. Rock physics templates and seismic inversion data are useful to understand these responses and to decrease uncertainty to the analysis of these anomalies.The integration of these methodologies allow to improve the understanding of the seismic amplitude response to different geological facies present in the study area.
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Calazans, Matos de Souza Andre Eduardo. "Seismic signature of gold mineralisation from rock physics, petrology characterisation and seismic modelling". Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/88380.
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To better understand the seismic response of lode gold deposits, we characterized in the laboratory over 140 core samples representing different lithologies from two gold mines located in Western Australia. These petrophysical and petrological data, along with a 2D geologic model of the mines, were used as input for rock physics and forward seismic modelling. The results indicate that the texture of the host rocks is the primary control of seismic reflectivity
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CATANIA, Maria. "SEISMIC NOISE ANALYSIS OF BROADBAND STATIONS OF THE ITALIAN SEISMIC NETWORK, USING POWER SPECTRAL DENSITY". Doctoral thesis, Università degli Studi di Palermo, 2022. https://hdl.handle.net/10447/543678.
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Rumpfhuber, Eva-Maria. "An integrated analysis of controlled-and passive source seismic data /". To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Polín-Tornero, Álvaro. "Resistivity and Seismic Characterization of an Embankment Dam. A Case Study in Northern Sweden". Thesis, Uppsala universitet, Geofysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-364563.
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The main cause of failure in embankment dams - which represent 75% of all dams in the world (ICOLD, 2018) - is the internal erosion produced by excessive seepage not accounted for in their designs. This erosion can cause that a small anomalous structure, not likely to be considered as risky, turns rapidly into a significant structural damage if not recognized on time. This creates a necessity for methods that can detect these anomalies in a non-intrusive, cost-effective and sensitive way. The purpose of this work is to analyse the strength of three geophysical methods (ERT and Seismic Refraction and Reflection) in detecting and accurately localizing anomalous structures inside an embankment dam. This study has been successfully approached in two different ways: by synthetic modelling and by an experimental field work at an embankment dam in northern Sweden. The results show that these methods are capable of detecting different structures in the interior of the dam in an accurate and rapid manner.Den främsta orsaken till brister i jordfyllningsdammar, som utgör 75% av alla dammar i världen (ICOLD, 2018) och är föremål för detta arbete, är inre erosion som orsakas av extrem läckage som togs inte med i beräkningar i deras konstruktioner. Denna erosion kan resultera i att en liten anomal struktur, som sannolikt inte anses vara riskabel, snabbt blir en betydande strukturell skada om den inte är uppmärksammas i tid. Därför krävs metoder som kan upptäcka dessa anomalier på ett icke-påträngande, kostnadseffektivt och känsligt sätt. Syftet med detta arbete är att analysera möjligheterna med tre geofysiska metoder (ERT, Seismisk Refraktion och Seismisk Reflektion) för att upptäcka och exakt lokalisera anomala strukturer inuti en jordfyllningsdamm. Denna studie har utförts på två fronter: genom (i) syntetisk modellering och (ii) ett experimentellt fältarbete vid en damm i norra Sverige. Resultaten visar att dessa metoder kan detektera olika strukturer inuti dammen på ett pålitligt och snabbt sätt.
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Yang, Ting. "Seismic constraints on structure beneath hotspots : earthquake tomography & finite frequency tomography approaches /". View online ; access limited to URI, 2006. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3232466.
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Quintana-Gallo, Patricio Ignacio. "The Nonlinear Dynamics Involved in the Seismic Assessment and Retrofit of Reinforced Concrete Buildings". Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2014. http://hdl.handle.net/10092/9999.
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Seismically vulnerable buildings constitute a major problem for the safety of human beings. In many parts of the world, reinforced concrete (RC) frame buildings designed and constructed with substandard detailing, no consideration of capacity design principles, and improper or no inclusion of the seismic actions, have been identified. Amongst those vulnerable building, one particular typology representative of the construction practice of the years previous to the 1970’s, that most likely represents the worst case scenario, has been widely investigated in the past. The deficiencies of that building typology are related to non-ductile detailing in beam column joints such as the use of plain round bars, the lack of stirrups inside the joint around the longitudinal reinforcement of the column, the use of 180° end hooks in the beams, the use of lap splices in potential ‘plastic hinge’ regions, and substandard quality of the materials. That type of detailing and the lack of a capacity design philosophy create a very fragile fuse in the structure where brittle inelastic behaviour is expected to occur, which is the panel zone region of exterior beam column joints.
The non-ductile typology described above was extensively investigated at the University of Canterbury in the context of the project ‘Retrofit Solutions for New Zealand Multi-Storey Buildings’ (2004-2011), founded by the ‘Foundation for Research, Science and Technology’ Tūāpapa Rangahau Pūtaiao. The experimental campaign prior to the research carried out by the author consisted of quasi-static tests of beam column joint subassemblies subjected to lateral loading regime, with constant and varying axial load in the column. Most of those specimens were representative of a plane 2D frame (knee joint), while others represented a portion of a space 3D frame (corner joints), and only few of them had a floor slab, transverse beams, and lap splices. Using those experiments, several feasible, cost-effective, and non-invasive retrofit techniques were developed, improved, and refined. Nevertheless, the slow motion nature of those experiments did not take into account the dynamical component inherent to earthquake related problems. Amongst the set of techniques investigated, the use of FRP layers for strengthening beam column joints is of particular interest due to its versatility and the momentum that its use has gained in the current state of the practice. That particular retrofit technique was previously used to develop a strengthening scheme suitable for plane 2D and space 3D corner beam column joints, but lacking of floor slabs. In addition, a similar scheme was not developed for exterior joints of internal frames, referred here as ‘cruciform’.
In this research a 2/5 scale RC frame model building comprising of two frames in parallel (external and internal) joined together by means of floor slabs and transverse beams, with non-ductile characteristics identical to those of the specimens investigated previously by others, and also including lap splices, was developed. In order to investigate the dynamic response of that building, a series of shake table tests with different ground motions were performed. After the first series of tests, the specimen was modified by connecting the spliced reinforcement in the columns in order to capture a different failure mode. Ground motions recorded during seismic events that occurred during the initial period of the experimental campaign (2010) were used in the subsequent experiments. The hierarchy of strengths and sequence of events in the panel zone region were evaluated in an extended version of the bending moment-axial load (M-N) performance domain developed by others. That extension was required due to the asymmetry in the beam cross section introduced by the floor slab. In addition, the effect of the torsion resistance provided by the spandrel (transverse beam) was included.
In order to upgrade the brittle and unstable performance of the as-built/repaired specimen, a practical and suitable ad-hoc FRP retrofit intervention was developed, following a partial retrofit strategy that aimed to strengthen exterior beam column joints only (corner and cruciform). The ability of the new FRP scheme to revert the sequence of events in the panel zone region was evaluated using the extended version of the M-N performance domain as well as the guidelines for strengthening plane joints developed by others. Weakening of the floor slab in a novel configuration was also incorporated with the purpose of reducing the flexural capacity of the beam under negative bending moment (slab in tension), enabling the damage relocation from the joint into the beam. The efficacy of the developed retrofit intervention in upgrading the seismic performance of the as-built specimen was investigated using shake table tests with the input motions used in the experiments of the as-built/repaired specimen.
Numerical work aimed to predict the response of the model building during the most relevant shake table tests was carried out. By using a simple numerical model with concentrated plasticity elements constructed in Ruaumoko2D, the results of blind and post-experimental predictions of the response of the specimen were addressed. Differences in the predicted response of the building using the nominal and the actual recorded motions of the shake table were investigated. The dependence of the accuracy of the numerical predictions on the assumed values of the parameters that control the hysteresis rules of key structural members was reviewed.
During the execution of the experimental campaign part of this thesis, two major earthquakes affected the central part of Chile (27 of February 2010 Maule earthquake) and the Canterbury region in New Zealand (22 February 2011 Canterbury earthquake), respectively. As the author had the opportunity to experience those events and investigate their consequences in structures, the observations related to non-ductile detailing and drawbacks in the state of the practice related to reinforced concrete walls was also addressed in this research, resulting in preliminary recommendations for the refinement of current seismic code provisions and assessment guidelines. The investigations of the ground motions recorded during those and other earthquakes were used to review the procedures related to the input motions used for nonlinear dynamic analysis of buildings as required by most of the current code provisions. Inelastic displacement spectra were constructed using ground motions recorded during the earthquakes mentioned above, in order to investigate the adequacy of modification factors used to obtain reduced design spectra from elastic counterparts. Finally a simplified assessment procedure for RC walls that incorporates capacity compatible spectral demands is proposed.
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Bradley, Brendon Archie. "Structure-Specific Probabilistic Seismic Risk Assessment". Thesis, University of Canterbury. Department of Civil and Natural Resources Engineering, 2009. http://hdl.handle.net/10092/2588.
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This thesis addresses a diverse range of topics in the area of probabilistic seismic risk
analysis of engineering facilities. This intentional path of diversity has been followed
primarily because of the relatively new and rapid development of this facet of earthquake
engineering. As such this thesis focuses on the rigorous scrutinization of current, and in
particular, simplified methods of seismic risk assessment; the development of novel aspects
of a risk assessment methodology which provides easily communicated performance
measures and explicit consideration for the many uncertainties in the entire earthquake
problem; and the application of this methodology to case-study examples including structures
supported on pile foundations embedded in liquefiable soils.
The state-of-the-art in seismic risk and loss assessment is discussed via the case study
of a 10 storey New Zealand office building. Particular attention is given to the quality and
quantity of information that such assessment methodologies provide to engineers and
stakeholders for rational decision-making.
Two chapters are devoted to the investigation of the power-law model for representing
the ground motion hazard. Based on the inaccuracy of the power-law model at representing
the seismic hazard over a wide range of exceedance rates, an alternative, more accurate,
parametric hazard model based on a hyperbola in log-log space is developed and applied to
New Zealand peak ground acceleration and spectral acceleration hazard data. A semianalytical
closed-form solution for the demand hazard is also developed using the hyperbolic
hazard model and applied for a case-study performance assessment. The power-law hazard
model is also commonly used to obtain a closed-form solution for the annual rate of structural
collapse (collapse hazard). The magnitude of the error in this closed-form solution due to
errors in the necessary functional forms of its constitutive relations is examined via a
parametric study.
A series of seven chapters are devoted to the further development of various aspects of
a seismic risk assessment methodology. Intensity measures for use in the estimation of
spatially distributed seismic demands and seismic risk assessment which are: easily
predicted; can predict seismic response with little uncertainty; and are unbiased regarding additional properties of the input ground motions are examined. An efficient numerical
integration algorithm which is specifically tailored for the solution of the governing risk
assessment equations is developed and compared against other common methods of
numerical integration. The efficacy of approximate uncertainty propagation in seismic risk
assessment using the so-called First-Order Second-Moment method is investigated.
Particular attention is given to the locations at which the approximate uncertainty propagation
is used, the possible errors for various computed seismic risk measures, and the reductions in
computational demands. Component correlations have to date been not rigorously considered
in seismic loss assessments due to complications in their estimation and tractable
methodologies to account for them. Rigorous and computationally efficient algorithms to
account for component correlations are presented. Particular attention is also given to the
determination of correlations in the case of limited empirical data, and the errors which may
occur in seismic loss assessment computations neglecting proper treatment of correlations are
examined. Trends in magnitude, distribution, and correlation of epistemic uncertainties in
seismic hazard analyses for sites in the San Francisco bay area are examined. The
characteristics of these epistemic uncertainties are then used to compare and contrast three
methods which can be used to propagate such uncertainties to other seismic risk measures.
Causes of epistemic uncertainties in component fragility functions, their evaluation, and
combination are also examined.
A series of three chapters address details regarding the seismic risk assessment of
structures supported on pile foundations embedded in liquefiable soils. A ground motion
prediction equation for spectrum intensity (found to be a desirable intensity measure for
seismic response analysis in liquefiable soils) is developed based on ground motion
prediction equations for spectral accelerations, which are available in abundance in literature.
Determination of intensity measures for the seismic response of pile foundations, which are
invariably located in soil deposits susceptible to liquefaction, is examined. Finally, a rigorous
seismic performance and loss assessment of a case-study bridge structure is examined using
rigorous ground motion selection, seismic effective stress analyses, and professional cost
estimates. Both direct repair and loss of functionality consequences for the bridge structure
are examined.
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Marroquín, Herrera Iván Dimitri. "Reservoir characterization through the application of seismic attributes : multiattribute and unsupervised seismic facies analyses". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95679.
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Seismic attributes are a descriptive and quantifiable characteristic of seismic data, and so they represent subsets of the total information contained in the original seismic data. Consequently, seismic attrjbutes can be important qualitative and quantitative predictors of physical reservoir properties. Seismic attribute analysis began with the search for bright spots in the late 1960s and early 1970s. Subsequent work in the last decades has established seismic attribute analysis as a valuable tool in reservoir characterization studies. I present in this thesis two seismic attribute analyses for the interpretation of the characteristics of the seismic trace to predict significant geological features (e.g., lithology, rock properties and/or fluid content). The first study is an example of the applicability of seismic attributes to predict geologic controls on production data in a coal bed methane reservoir. Based on the calibration of log data with seismic data procedure, I defined a window of analysis, from which I computed amplitude, frequency and phase related attributes. Then, I used a quantitative multiattribute analysis to derive a seismic attribute-based model that predicts coal thickness. Thereafter, I used with a curvature attribute analysis with the objective to map subtle structural features and predict areas with enhanced permeability. The integration of production data with results achieved from both attribute analyses indicates that best production is associated with thicker coal and the immediate vicinity to seismically defined structures. [...]Les attributs sismiques ont comme caractéristique de pouvoir décrire et quantifier les données sismiques, de telle manière qu’ils représentent un sous-ensemble de l’information totale contenue dans les données originales. En conséquence, les attributs sismiques peuvent être d’importants paramètres qualitatifs et quantitatifs des propriétés physiques d’un réservoir. L’analyse d’attributs sismiques a commencé avec la prospection de tâches lumineuses (<< bright spots >>) vers la fin des années 1960 et début des années 1970. Des travaux subséquents pendant les dernières décennies ont permis d’établir l’analyse d’attributs sismiques comme un outil valable lors d’études de caractérisation d’un réservoir. Je présente dans cette thèse deux études d’attributs sismiques pour l’interprétation de la forme de la trace sismique afin de prédire des caractéristiques géologiques significatives tels que: la lithologie, les propriétés des roches et/ou le contenu liquide. La première étude est un exemple de l’application d’attributs sismiques pour prédire des contrôles géologiques sur la production d’un réservoir coalbed methane. D’après les résultats de la calibration des diagraphies au câble avec des données sismiques, j’ai défini une fenêtre d’investigation à partir de laquelle des attributs sismiques de type amplitude, fréquence et phase ont été calculés. J’ai utilisé une analyse muIti-attribut pour dériver un model statistique dans le but d’estimer l’épaisseur du réservoir. Par la suite, j’ai utilisé des attributs mesurant la courbature d’une surface pour mettre en relief de subtiles structures géologiques et prédire les régions dans le réservoir avec une perméabilité augmentée. L’intégration des données de production avec les résultats obtenus lors d’analyses d’attributs sismiques indique que la meilleure production est en association avec l’épaississement du réservoir et le voisinage immédiat de structures géologiques. [...]
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Brana, Luisa Patricia. "Imaging and interpreting seismic scattering in the crust and mantle using regional seismic networks". Thesis, University of Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393905.
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Beckwith, James Alexander. "Constant- and frequency-dependent seismic quality factors measured from surface and borehole seismic surveys". Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/17147/.
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In this thesis, I have introduced and presented a new time-frequency distribution, termed the Signal-Dependent Distribution (SDD), which can by-pass the Gabor Uncertainty Principle, with a trade-off instead between joint time-frequency transform and suppression of transform artefacts. In two different synthetic seismic data sets, the SDD provided estimates of attenuation in closer agreement to the input attenuation than those from a fixed- (short-time-Fourier-transform) and a variable-window (Stockwell transform) time-frequency transform. The SDD also provided spectral ratio surfaces from a pre-stack gathers, using the pre-stack Q inversion (PSQI) method, more consistent with a frequency-independent attenuation model than the fixed- and variable-window transforms. Frequency-dependent Q can be estimated in the PSQI method if the seismic attenuation quality factor, Q, is assumed to follow a powerlaw frequency-dependence, Q=af^b. Utilising the SDD to form spectra, the modified PSQI method found a frequency exponent, b, of only 0.074±0.001 (median 0.06) for the Kinnoull field in the North Sea, implying that an approximation of frequency-independent Q is valid for the Kinnoull dataset. Higher b values were found to coincide with sudden, localised, drops in centroid frequency beneath amplitude anomalies: they were inferred not to be due to a genuine frequencydependence of Q, but to interference on the spectral ratio surface. The SDD was then used to estimate spectra in the PSQI method applied to: the Kinnoull pre-stack surface seismic dataset; a spectral ratio method applied to a stacked surface seismic survey; and VSP data for well 16/23-7. The three sets of attenuation estimates were compared to each other, and also to average energy and average centroid frequency maps derived from the stacked seismic dataset. Only the attenuation values estimated from the stacked seismic data and the VSP data correlated well with each other (median 1000/Q of 9.2±0.1 and 10.4±2.0 respectively). 1/Q attenuation maps from stacked and pre-stack seismic data did not correlate coherently with the centroid frequency or energy maps, nor did the pre-stack attenuation values correlate with the VSP data. This inconsistency remains unexplained. This method of estimating frequency-dependent seismic attenuation quality factor was then applied to 6 VSP datasets located in the Barents Sea. Although the formation-averaged frequency exponent b varied between -0.1 and 0.2, the median value was 0.02, again supporting an assumption of frequency-independent attenuation within the seismic bandwidth. Using coincident well logs, statistically significant correlations were found between intrinsic attenuation and bulk, shear, and Young’s moduli, and Poisson’s ratio. In contrast, no robust relationship was found between petrophysical parameters and attenuation in the seismic bandwidth. However, a squirt flow model fitted to the estimated power-law curves of frequency-dependent 1/Q implied crack aspect of between 1 and 6 x 10^−3, similar to the crack aspect ratio of 0.1-1.0 x 10^−3 expected to be responsible for the majority of squirt flow induced attenuation.
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Ghaychi, Afrouz Setareh. "Seismic Wave Velocity Variations in Deep Hard Rock Underground Mines by Passive Seismic Tomography". Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/97890.
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Mining engineers are tasked with ensuring that underground mining operations be both safe and efficiently productive. Induced stress in deep mines has a significant role in the stability of the underground mines and hence the safety of the mining workplace because the behavior of the rock mass associated with mining-induced seismicity is poorly-understood. Passive seismic tomography is a tool with which the performance of a rock mass can be monitored in a timely manner. Using the tool of passive seismic tomography, the advance rate of operation and mining designs can be updated considering the induced stress level in the abutting rock. Most of our current understanding of rock mass behavior associated with mining-induced seismicity comes from numerical modeling and a limited set of case studies. Therefore, it is critical to continuously monitor the rock mass performance under induced stress. Underground stress changes directly influence the seismic wave velocity of the rock mass, which can be measured by passive seismic tomography. The precise rock mass seismicity can be modeled based on the data recorded by seismic sensors such as geophones of an in-mine microseismic system. The seismic velocity of rock mass, which refers to the propagated P-wave velocity, varies associated with the occurrence of major seismic events (defined as having a local moment magnitude between 2 to 4). Seismic velocity changes in affected areas can be measured before and after a major seismic event in order to determine the highly stressed zones. This study evaluates the seismic velocity trends associated with five major seismic events with moment magnitude of 1.4 at a deep narrow-vein mine in order to recognize reasonable patterns correlated to induced stress redistribution. This pattern may allow recognizing areas and times which are prone to occurrence of a major seismic event and helpful in taking appropriate actions in order to mitigate the risk such as evacuation of the area in abrupt cases and changing the aggressive mine plans in gradual cases. In other words, the high stress zones can be distinguished at their early stage and correspondingly optimizing the mining practices to prevent progression of high stress zones which can be ended to a rock failure. For this purpose a block cave mine was synthetically modeled and numerically analyzed in order to evaluate the capability of the passive seismic tomography in determining the induced stress changes through seismic velocity measurement in block cave mines. Next the same method is used for a narrow vein mine as a case study to determine the velocity patterns corresponding to each major seismic event.Doctor of Philosophy
Mining activities unbalance the stress distribution underground, which is called mining induced stress. The stability of the underground mines is jeopardized due to accumulation of induced stress thus it is critical for the safety of the miners to prevent excessive induced stress accumulation. Hence it is important to continuously monitor the rock mass performance under the induced stress which can form cracks or slide along the existing discontinuities in rock mass. Cracking or sliding releases energy as the source of the seismic wave propagation in underground rocks, known as a seismic event. The velocity of seismic wave propagation can be recorded and monitored by installing seismic sensors such as geophones underground. The seismic events are similar to earthquakes but on a much smaller scale. The strength of seismic events is measured on a scale of moment magnitude. The strongest earthquakes in the world are around magnitude 9, most destructive earthquakes are magnitude 7 or higher, and earthquakes below magnitude 5 generally do not cause significant damage. The moment magnitude of mining induced seismic events is typically less than 3. In order to monitor mining induced stress variations, the propagated seismic wave velocity in rock mass is measured by a series of mathematical computations on recorded seismic waves called passive seismic tomography, which is similar to the medical CT-scan machine. Seismic wave velocity is like the velocity of the vibrating particles of rock due to the released energy from a seismic event. This study proposes to investigate trends of seismic velocity variations before and after each seismic event. The areas which are highly stressed have higher seismic velocities compared to the average seismic velocity of the entire area. Therefore, early recognition of highly stressed zones, based on the seismic velocity amount prior the occurrence of major seismic events, will be helpful to apply optimization of mining practices to prevent progression of high stress zones which can be ended to rock failures. For this purpose, time-dependent seismic velocity of a synthetic mine was compared to its stress numerically. Then, the seismic data of a narrow vein mine is evaluated to determine the seismic velocity trends prior to the occurrence of at least five major seismic events as the case study.
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He, Yanxiao. "Seismic waveform simulation using hydro-mechanical reservoir models to assess time-lapse seismic attributes". Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/8864/.
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Time-lapse seismic monitoring provides information about subsurface changes in reservoir fluid-saturations, stress and strain. Using multi-vintage surface seismic surveys, time-lapse seismic measurements, quantified through seismic attributes such as travel-time shifts and reflection amplitude differences, are serving as a valuable tool for reservoir and geomechanical model calibration and hence, improving reservoir predictions. In this thesis, I introduce and develop an integrated seismic and coupled fluid-flow and geomechanical workflow for computing time-lapse dynamic changes from surface reflection synthetic seismograms that focuses on reducing the error and uncertainty in time-lapse seismic analysis. The workflow is demonstrated using both an anisotropic ray-based algorithm and an isotropic finite-difference full-waveform algorithm on a suite of simple four layer reservoir models as well as two numerical geomechanical reservoir models: a two-fault graben structure model and a complex deep reservoir model undergoing depletion. Using these models, a variety of acquisition strategies and data processing methods are applied. First, I generate synthetic seismograms using an anisotropic ray tracing algorithm to investigate the effects of time-lapse subsurface changes on seismic attributes. The reservoir models with time-variant properties, constructed from output of coupled fluid-flow and geomechanical simulation and a stress-sensitive rock physics model, have geometry characterised by three compartments that are offset by two normal faults having high or low fluid-flow transmissibility. Travel-time shifts and reflection amplitude changes are used to evaluate physical changes within the reservoir system. The results suggest that compartmentalisation can be identified but that it is important to understand the stress path of the reservoir if quantitatively accurate estimates of velocity changes and strains are required. Next, I explore the feasibility of using time-lapse AVO and AVOA analysis to monitor reservoir compartmentalisation as well as to evaluate stress induced seismic anisotropy. Time-lapse seismic reflection amplitude changes are estimated using an anisotropic ray tracing simulation, as well as the exact and approximate reflectivity solutions. The time-lapse AVO and AVOA signatures display noticeable deviations between models experiencing isotropic and anisotropic TI (VTI and HTI) elasticity changes. The results imply that time-lapse AVO and AVOA analysis can be applied as a potential means for qualitatively and semi-quantitatively linking azimuthal anisotropy changes caused by reservoir production to pressure/stress changes. I then extend the integrated scheme using a geomechanical model for a complex deep reservoir undergoing compaction and an isotropic finite-difference full-waveform modelling algorithm to study the influence of overburden effective stress perturbations. The full-waveform synthetic waveforms are used to evaluate time-lapse seismic attributes resolution for more realistic synthetics. The time-lapse seismic travel-time shifts and time strains (from pre-stack and post-stack data) calculated from the synthetic seismograms are in a reasonable agreement with the respective input elasticity model. The results show that the time-lapse technique is reasonably accurate for predicting overburden velocity changes and hence geomechanical effects. Finally, I propose a new algorithm to measure time-lapse vertical travel-time shifts in seismic pre-stack shot and CMP gather data by tracking traces of a constant horizontal slowness in the tau-p domain. The approach is used to estimate layer vertical travel-time shifts, a 1D reservoir compaction-dilation coefficient, and hence calculate both velocity and thickness changes within the reservoir and overburden. I compare the estimates of layer interval vertical time-lapse travel-time shifts, and velocity and thickness changes with those of the input model. The results indicate that the new tau-p time-lapse method produces sufficiently accurate results compared to conventional methods. The results of the thesis indicate that time-lapse seismic monitoring in conjunction with reservoir fluid-flow and geomechanical simulations, rock physics models and seismic numerical modelling, has the potential to be a valuable tool for accurate measurement (both qualitatively and quantitatively) of time-lapse effects due to reservoir pore pressure induced geomechanical deformations. Time-lapse seismic data has the potential to help in the calibration of geomechanical reservoir models.
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Johansen, Owe. "Seismic Shot Processing on GPU". Thesis, Norwegian University of Science and Technology, Department of Computer and Information Science, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9956.
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Todays petroleum industry demand an ever increasing amount of compu- tational resources. Seismic processing applications in use by these types of companies have generally been using large clusters of compute nodes, whose only computing resource has been the CPU. However, using Graphics Pro- cessing Units (GPU) for general purpose programming is these days becoming increasingly more popular in the high performance computing area. In 2007, NVIDIA corporation launched their framework for developing GPU utilizing computational algorithms, known as the Compute Unied Device Architec- ture (CUDA), a wide variety of research areas have adopted this framework for their algorithms. This thesis looks at the applicability of GPU techniques and CUDA for off-loading some of the computational workload in a seismic shot modeling application provided by StatoilHydro to modern GPUs. This work builds on our recent project that looked at providing check- point restart for this MPI enabled shot modeling application. In this thesis, we demonstrate that the inherent data parallelism in the core finite-difference computations also makes our application well suited for GPU acceleration. By using CUDA, we show that we could do an efficient port our application, and through further refinements achieve significant performance increases. Benchmarks done on two different systems in the NTNU IDI (Depart- ment of Computer and Information Science) HPC-lab, are included. One system is a Intel Core2 Quad Q9550 @2.83GHz with 4GB of RAM and an NVIDIA GeForce GTX280 and NVIDIA Tesla C1060 GPU. Our sec- ond testbed was an Intel Core I7 Extreme (965 @3.20GHz) with 12GB of RAM hosting an NVIDIA Tesla S1070 (4X NVIDIA Tesla C1060). On this hardware, speedups up to a factor of 8-14.79 compared to the original se- quential code are achieved, confirming the potential of GPU computing in applications similar to the one used in this thesis.