To see the other types of publications on this topic, follow the link: Geophysical data interpretation.
Dissertations / Theses on the topic 'Geophysical data interpretation'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 32 dissertations / theses for your research on the topic 'Geophysical data interpretation.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Johansson, Linnéa. "Modelling and interpretation of VTEM data from Soppero, Sweden." Thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-64879.
Full textAbstract:
The geological and geophysical knowledge about the northernmost part of Sweden has recently increased due to the Barents project, which includes acquisition of modern geophysical and geological information on behalf of the Swedish Geological Survey (SGU). During August 2013, a helicopter-borne versatile time domain electromagnetic (VTEM) survey was performed by Geotech Ltd, in the Soppero area northeast of Kiruna. From the VTEM measurements, a number of TEM anomalous zones have been identified and two of them are located south and southeast of the Lannavaara village. The main conductive features in the Lannavaara area can be explained by the presence of graphitic schist, which is spatially associated with a number of sulphide and iron oxide mineralisation occurrences. In this project, Maxwell thin sheet modelling and EM Flow conductivity-depth-imaging (CDI) software have been applied to selected anomalies in the Lannavaara area, for the purpose of extracting geometrical parameters of conductive features. This information has been used in order to confirm the structural framework of the area and evaluate the utility of VTEM measurements in this geological environment. In general, Maxwell thin sheet models of anomalies with small amplitudes show a better correlation with existing drill holes than models of anomalies with large amplitudes. The use of small amplitudes managed to confirm the structural model in the central part of the investigated area, which is an anticline. However, the use of different models and their distribution across the area is limited. Compared with Maxwell, CDIs from EM Flow provided a better way of confirming the general structural model in the area, although they include artefacts due to strong lateral gradients in conductivity. The Lannavaara area has also been investigated by VLF, Slingram and magnetic measurements and based on these data, multivariate analysis in SiroSOM reveals a strong correlation between VTEM and Slingram data, while VLF data appears to have much less or more complicated correlation with the other data sets. In summary, the results from the various software raise a question about the geological complexity in parts of the Lannavaara area, which may include multiple layers of graphitic schist, possibly expressed as smooth transitions in conductivity when represented by data from electromagnetic methods.
2
Gigandet, Katherine M. "Processing and Interpretation of Illinois Basin Seismic Reflection Data." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1401309913.
Full text
3
Kozlovskaya, E. (Elena). "Theory and application of joint interpretation of multimethod geophysical data." Doctoral thesis, University of Oulu, 2001. http://urn.fi/urn:isbn:9514259602.
Full textAbstract:
Abstract
This work is devoted to the theory of joint interpretation of multimethod geophysical data and its
application to the solution of real geophysical inverse problems. The targets of such joint interpretation
can be geological bodies with an established dependence between various physical properties that cause
anomalies in several geophysical fields (geophysical multiresponse). The establishing of the relationship
connecting the various physical properties is therefore a necessary first step in any joint interpretation
procedure. Bodies for which the established relationship between physical properties is violated
(single-response bodies) can be targets of separate interpretations. The probabilistic (Bayesian) approach
provides the necessary formalism for addressing the problem of the joint inversion of multimethod
geophysical data, which can be non-linear and have a non-unique solution. Analysis of the lower limit of
resolution of the non-linear problem of joint inversion using the definition of e-entropy demonstrates that
joint inversion of multimethod geophysical data can reduce non-uniqueness in real geophysical inverse
problems. The question can be formulated as a multiobjective optimisation problem (MOP), enabling the
numerical methods of this theory to be employed for the purpose of geophysical data inversion and for
developing computer algorithms capable of solving highly non-linear problems. An example of such a problem
is magnetotelluric impedance tensor inversion with the aim of obtaining a 3-D resistivity distribution. An
additional area of application for multiobjective optimisation can be the combination of various types of
uncertain information (probabilistic and non-probabilistic) in a common inversion scheme applicable to
geophysical inverse problems. It is demonstrated how the relationship between seismic velocity and density
can be used to construct an algorithm for the joint interpretation of gravity and seismic wide-angle
reflection and refraction data. The relationship between the elastic and electrical properties of rocks,
which is a necessary condition for the joint inversion of data obtained by seismic and electromagnetic
methods, can be established for solid- liquid rock mixtures using theoretical modelling of the elastic and
electrical properties of rocks with a fractal microstructure and from analyses of petrophysical data and
borehole log data.
4
Tsourlos, Panagiotis. "Modelling, interpretation and inversion of multielectrode resistivity survey data." Thesis, University of York, 1995. http://etheses.whiterose.ac.uk/14017/.
Full text
5
Ström, Tobias. "A geophysical study of the Mertainen area : Modelling and interpretation of primarily aeromagnetic data." Thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-63850.
Full textAbstract:
Nautanen Deformation Zone, is a prominent deformation zone in the Malmfälten area, which is of importance to understand for mineral exploration purposes. In spite of diverse geophysical data being available in Malmfälten and the good correlation between airborne measurements and geological observations, the area has not been fully investigated in detail using the aforementioned available data. A geological feature in connection with the Mertainen magnetite-breccia apatite iron ore deposit has been studied. Methods include the study of geological maps, the study of analytic signals of magnetic and gravity data, data processing, potential field- and 3D modelling and the interpretation of aforementioned models. Based on the observed and modelled data a fold structure has been detected in connection with Mertainen, and several mineralizations are believed to be structurally related to this fold. Furthermore, a potential mineralization structurally related with the fold has been detected, though it is quite likely that it isn't economically viable.<br>Nautanen Deformation Zone, är en framträdande deformationszon i Malmfälten området, vilken är av betydelse att förstå för mineral prospekterings ändåmål. Trotts att det finns ett stort utbud av geofysiska data i Malmfälten och att det finns en god korrelation mellan de flyggeofysiska mätningarna och geologiska observationer, så har området inte undersökts fullständigt med den tillgängliga datan. En geologisk struktur i koppling till apatit järn malms fyndigheten Mertainen has studerats. Bland metoder ingår studie av geologiska kartor, studie av de analytiska signlar hos magnetiska och gravimetriska data, data processering, potential fält- och 3D modellering samt tolkningen av ovannämnda modeller. Baserat på den observerade samt modellerade datan har en veck strucktur upptäckts i koppling till Mertainen, och flertalet mineraliseringar tros vara strukturellt relaterade till detta veck. Dessutom har en potentiell mineralisering strukturellt relaterad till vecket upptäckts, dock är det väldigt troligt att den inte är ekonomiskt brytbar.
6
Broome, H. John Carleton University Dissertation Geology. "Processing and interpretation of regional geophysical data from the Amer Lake/Wager Bay area, district of Keewatin." Ottawa, 1989.
Find full text
7
Sheffer, Megan Rae. "Forward modelling and inversion of streaming potential for the interpretation of hydraulic conditions from self-potential data." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/235.
Full textAbstract:
The self-potential method responds to the electrokinetic phenomenon of streaming potential and has been applied in hydrogeologic and engineering investigations to aid in the evaluation of subsurface hydraulic conditions. Of specific interest is the application of the method to embankment dam seepage monitoring and detection. This demands a quantitative
interpretation of seepage conditions from the geophysical data.
To enable the study of variably saturated flow problems of complicated geometry, a three-dimensional finite volume algorithm
is developed to evaluate the self-potential distribution resulting from subsurface fluid flow. The algorithm explicitly calculates
the distribution of streaming current sources and solves for the self-potential given a model of hydraulic head and prescribed distributions of the streaming current cross-coupling conductivity and electrical resistivity. A new laboratory apparatus is developed to measure the streaming potential coupling coefficient
and resistivity in unconsolidated soil samples. Measuring both of these parameters on the same sample under the same conditions
enables us to properly characterize the streaming current cross-coupling conductivity coefficient. I present the results of a laboratory investigation to study the influence of soil and fluid parameters on the cross-coupling coefficient, and characterize this property for representative well-graded embankment soils. The streaming potential signals associated with preferential seepage through the core of a synthetic embankment dam model are studied using the forward modelling algorithm and measured electrical properties to assess the sensitivity of the self-potential method in detecting internal erosion. Maximum self-potential anomalies are shown to be linked to large localized
hydraulic gradients that develop in response to piping, prior to any detectable increase in seepage flow through the dam. A linear
inversion algorithm is developed to evaluate the three-dimensional distribution of hydraulic head from self-potential data, given a known distribution of the cross-coupling coefficient and electrical resistivity. The inverse problem is solved by
minimizing an objective function, which consists of a data misfit that accounts for measurement error and a model objective function that incorporates a priori information. The algorithm is suitable
for saturated flow problems or where the position of the phreatic surface is known.
8
Jungmann, Matthias Verfasser], Christoph [Akademischer Betreuer] [Clauser, Thomas Akademischer Betreuer] Berlage, and Benjamin [Akademischer Betreuer] [Berkels. "Interpretation of Geophysical Data with Higher-Level Image Processing Methods / Matthias Jungmann ; Christoph Clauser, Thomas Berlage, Benjamin Berkels." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1162503335/34.
Full text
9
Jungmann, Matthias [Verfasser], Christoph [Akademischer Betreuer] Clauser, Thomas Akademischer Betreuer] Berlage, and Benjamin [Akademischer Betreuer] [Berkels. "Interpretation of Geophysical Data with Higher-Level Image Processing Methods / Matthias Jungmann ; Christoph Clauser, Thomas Berlage, Benjamin Berkels." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1162503335/34.
Full text
10
Tadesse, Ketsela. "Integrated geophysical data processing and interpretation of crustal structure in Ethiopia with emphasis on the Ogaden basin and adjacent areas." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
Full text
11
Corradini, Erica [Verfasser], Wolfgang [Akademischer Betreuer] Rabbel, and Valentin Berit [Gutachter] Eriksen. "Bridging the scales: model-driven integrative interpretation of archaeological and geophysical data. / Erica Corradini ; Gutachter: Valentin Berit Eriksen ; Betreuer: Wolfgang Rabbel." Kiel : Universitätsbibliothek Kiel, 2020. http://d-nb.info/1220691305/34.
Full text
12
Graciolli, Vinicius Medeiros. "A novel classification method applied to well log data calibrated by ontology based core descriptions." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/174993.
Full textAbstract:
Um método para a detecção automática de tipos litológicos e contato entre camadas foi desenvolvido através de uma combinação de análise estatística de um conjunto de perfis geofísicos de poços convencionais, calibrado por descrições sistemáticas de testemunhos. O objetivo deste projeto é permitir a integração de dados de rocha em modelos de reservatório. Os testemunhos são descritos com o suporte de um sistema de nomenclatura baseado em ontologias que formaliza extensamente uma grande gama de atributos de rocha. As descrições são armazenadas em um banco de dados relacional junto com dados de perfis de poço convencionais de cada poço analisado. Esta estrutura permite definir protótipos de valores de perfil combinados para cada litologia reconhecida através do cálculo de média e dos valores de variância e covariância dos valores medidos por cada ferramenta de perfilagem para cada litologia descrita nos testemunhos. O algoritmo estatístico é capaz de aprender com cada novo testemunho e valor de log adicionado ao banco de dados, refinando progressivamente a identificação litológica. A detecção de contatos litológicos é realizada através da suavização de cada um dos perfis através da aplicação de duas médias móveis de diferentes tamanhos em cada um dos perfis. Os resultados de cada par de perfis suavizados são comparados, e as posições onde as linhas se cruzam definem profundidades onde ocorrem mudanças bruscas no valor do perfil, indicando uma potencial mudança de litologia. Os resultados da aplicação desse método em cada um dos perfis são então unificados em uma única avaliação de limites litológicos Os valores de média e variância-covariância derivados da correlação entre testemunhos e perfis são então utilizados na construção de uma distribuição gaussiana n-dimensional para cada uma das litologias reconhecidas. Neste ponto, probabilidades a priori também são calculadas para cada litologia. Estas distribuições são comparadas contra cada um dos intervalos litológicos previamente detectados por meio de uma função densidade de probabilidade, avaliando o quão perto o intervalo está de cada litologia e permitindo a atribuição de um tipo litológico para cada intervalo. O método desenvolvido foi testado em um grupo de poços da bacia de Sergipe- Alagoas, e a precisão da predição atingida durante os testes mostra-se superior a algoritmos clássicos de reconhecimento de padrões como redes neurais e classificadores KNN. O método desenvolvido foi então combinado com estes métodos clássicos em um sistema multi-agentes. Os resultados mostram um potencial significante para aplicação operacional efetiva na construção de modelos geológicos para a exploração e desenvolvimento de áreas com grande volume de dados de perfil e intervalos testemunhados.<br>A method for the automatic detection of lithological types and layer contacts was developed through the combined statistical analysis of a suite of conventional wireline logs, calibrated by the systematic description of cores. The intent of this project is to allow the integration of rock data into reservoir models. The cores are described with support of an ontology-based nomenclature system that extensively formalizes a large set of attributes of the rocks, including lithology, texture, primary and diagenetic composition and depositional, diagenetic and deformational structures. The descriptions are stored in a relational database along with the records of conventional wireline logs (gamma ray, resistivity, density, neutrons, sonic) of each analyzed well. This structure allows defining prototypes of combined log values for each lithology recognized, by calculating the mean and the variance-covariance values measured by each log tool for each of the lithologies described in the cores. The statistical algorithm is able to learn with each addition of described and logged core interval, in order to progressively refine the automatic lithological identification. The detection of lithological contacts is performed through the smoothing of each of the logs by the application of two moving means with different window sizes. The results of each pair of smoothed logs are compared, and the places where the lines cross define the locations where there are abrupt shifts in the values of each log, therefore potentially indicating a change of lithology. The results from applying this method to each log are then unified in a single assessment of lithological boundaries The mean and variance-covariance data derived from the core samples is then used to build an n-dimensional gaussian distribution for each of the lithologies recognized. At this point, Bayesian priors are also calculated for each lithology. These distributions are checked against each of the previously detected lithological intervals by means of a probability density function, evaluating how close the interval is to each lithology prototype and allowing the assignment of a lithological type to each interval. The developed method was tested in a set of wells in the Sergipe-Alagoas basin and the prediction accuracy achieved during testing is superior to classic pattern recognition methods such as neural networks and KNN classifiers. The method was then combined with neural networks and KNN classifiers into a multi-agent system. The results show significant potential for effective operational application to the construction of geological models for the exploration and development of areas with large volume of conventional wireline log data and representative cored intervals.
13
Sterritt, Victoria Athena. "Understanding physical property : mineralogy relationships in the context of geologic processes in the ultramafic rock-hosted mineral deposit environment : aiding interpretation of geophysical data." Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/32686.
Full textAbstract:
Inversion of potential field geophysical data to generate physical property models is
becoming increasingly common in the exploration industry. This study aimed to develop
relationships between physical properties and mineralogy in ultramafic rock-hosted mineral
deposits, based on an analysis of the crater facies-dominated Anuri kimberlite (Canada) and the
intrusive magmatic sulfide deposit at Kabanga (Tanzania). Physical property distributions for
rock types and minerals that contribute to density and magnetic susceptibility were characterized
in both deposits.
Magnetic susceptibility is directly related to magnetite abundance, which is an igneous phase
and is produced by serpentinization of ultramafic rocks of both deposits. Magnetite in kimberlite
also occurs in crustal xenoliths, which dilute the diamond content. Consequently, susceptibility
in the Anuri kimberlite is inversely related to diamond grade. In the Kabanga magmatic sulfide
deposit, susceptibility is unrelated to ore content, but does indicate the degree of serpentinization.
Density is a function of dense minerals concentrated with ore during primary sorting and
settling processes in both deposits. As such, density is directly correlated with ore in both
volcaniclastic kimberlite breccia of the Anuri kimberlite and ultramafic rocks at Kabanga.
However, serpentinization decreases the density of ultramafic rocks significantly, masking any
density anomalies associated with sulfide minerals. Modeling demonstrates that a pervasively
serpentinized rock with up to 50% sulfide minerals can have a density equal to that of a barren
ultramafic rock.
A combination of susceptibility and density can be used to identify high-grade rocks in both
deposits. In the Anuri kimberlite, rocks with high diamond contents have susceptibilities less
than 10 x 10⁻³ SI and densities of 2.42 - 2.51 g/cm³. In magmatic sulfide deposits, susceptibility
and density can be used to accurately calculate ore mineral abundances.
Relationships developed between physical properties and mineralogy for these deposits can
not only be applied to other crater facies-dominated kimberlites and both intrusive and extrusive
magmatic sulfide deposits, but also to other ultramafic rock-hosted mineral deposits with
comparable geologic processes. Consequently, both magnetic and gravity surveys can be
interpreted in combination to give a powerful remote tool in predicting grade.<br>Science, Faculty of<br>Earth, Ocean and Atmospheric Sciences, Department of<br>Graduate
14
Fan, Guangwei. "Inversion of seismic waveform data and its interpretation." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185965.
Full textAbstract:
Seismic waveforms are a complex combination of the seismic source process, propagation effects and distortions due to mechanical recording. The inversion of long-period, teleseismic body waves has proven quite effective in determining source parameters of moderate to large-sized earthquakes. The focal mechanisms from moderate-sized events also have been recovered using regional waveforms. In this thesis, the waveform inversion method is applied to moderate to large-sized earthquakes at teleseismic distance and extended to small earthquakes at regional and local distance. The moment tensor formalism provides a framework for the seismic source inversion problem. It can be solved when broad band or occasionally band-limited waveform data from a single station or sparse network are available. The signature of the seismic source orientation on the waveform is robust if the P, SV and SH displacement waveforms from a single station are used and the gross crustal structure along the travel path is known. The focal mechanisms of the two small earthquakes, which occurred in the Rio Grande Rift, New Mexico, were determined and are consistent with those from the P-wave first motion data. This moment tensor inversion method was also used to analyze the small aftershocks of the 1991 Costa Rica earthquake (M(s) = 7.6). It was found that the focal mechanisms of the aftershocks can be recovered from three-component waveform data recorded by a sparse mid-period network. The focal mechanism signature on the waveforms is not very sensitive to the details of the crustal structure, which are poorly known in this study. However, the source depths are not well constrained due to the trade-off with the assumed crustal model since the details of the crustal structure strongly affect the body waveforms at regional distances. The focal mechanisms of small aftershocks were used in studying regional tectonics setting. The teleseismic waveform inversion method is used to investigate moderate- to large-sized earthquakes in the Pamir-Karakorum region. Most shallow earthquakes are within the upper crust with focal depths less than 20 km. Nearly horizontal compressional P axes of shallow events trend in an approximately north-south direction, consistent with convergence of the two continental plates. Both the hypocentral distribution and focal mechanisms of intermediate-depth events clearly delineate a southward-dipping Wadati-Benioff zone, representing the subduction of the continental lithosphere of the Eurasian plate in the Pamir-Karakorum region.
15
Wood, Andrew Richard. "Theoretical studies of atmospheric tides for the interpretation of satellite data." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359582.
Full text
16
Luo, Simon S. "Improved methods of reflection seismic data processing for velocity estimation, imaging, and interpretation." Thesis, Colorado School of Mines, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3668324.
Full textAbstract:
<p> Seismic images and the geologic information they provide contribute significantly to our understanding of the earth's subsurface. In this thesis, I focus on methods relevant for constructing and interpreting seismic images, including methods for velocity estimation, seismic imaging, and interpretation, which together address key aspects of reflection seismic data processing. Specifically, I propose improved methods for semblance-based normal-moveout velocity analysis, for seismic imaging by least-squares migration, and for the automatic extraction of geologic horizons. </p><p> To compute a seismic image, an estimate of the subsurface velocity is needed. One common method for constructing an initial velocity model is semblance-based normal-moveout (NMO) velocity analysis, in which semblance spectra are analyzed to identify peaks in semblance corresponding to effective NMO velocities. The accuracy of NMO velocities obtained from semblance spectra depends on the sensitivity of semblance to changes in velocity. By introducing a weighting function in the semblance calculation, I emphasize terms that are more sensitive to velocity changes, which, as a result, increases the resolution of semblance spectra and allows for more accurate NMO velocity estimates. </p><p> Following velocity analysis, a seismic image of the subsurface is computed by migrating the recorded data. However, while velocity analysis is an important step in processing reflection seismic data, in practice we expect errors in the velocity models we compute, and these errors can degrade a seismic image. Instead of minimizing the difference between predicted and observed seismic data as is done for conventional migration, I propose to minimize the difference between predicted and time-shifted observed data, where the time shifts are the traveltime differences between predicted and observed data. With this misfit function, an image computed for an erroneous velocity model contains features similar to those obtained using a more accurate velocity. </p><p> Once a seismic image is computed, a common task in interpreting the image is the identification of geologic horizons. As an alternative to manual picking or autotracking, I propose methods to automatically and simultaneously extract all horizons within an image. To extract geologic horizons, a seismic image is unfaulted and unfolded to restore horizons to an undeformed, horizontal state from which they can be easily identified and extracted.</p>
17
Miles, Warner Frederick. "An interpretation of high resolution aeromagnetic data over the Manitouwadge greenstone belt, Ontario, Canada." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0005/MQ36726.pdf.
Full text
18
Hjärtén, Martin. "Master thesis in interpretation of controlled-source radiomagnetotelluric data from Hallandsåsen." Thesis, Uppsala University, Geophysics, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8015.
Full textAbstract:
<p>Controlled Source Tensor Magnetotelluric (CSTMT) ground measurements were executed on the Hallandsåsen horst where a major tunnel is under construction. The instrument system EnviroMT are used for this purpose. The major research aspect of this thesis has been to form an opinion of the effectiveness of the method by comparing the results from the CSTMT survey with a prior investigation performed with the DC resistivity method. Another important part of this thesis has been to compile the basic and fundamental CSTMT and RMT theory, in a way that people outside the EM community easily can be introduced to the subject.</p><p>When comparing the different inversion models from the CSTMT and DC resistivity surveys one can see differences in the depth at which the conductors are resolved. In the CSTMT inversion models (TE+TM) there are two conductors that possibly can reach the depth of the tunnel in construction. These conductors are not resolved at the deeper structures in the DC resistivity models. Whether the conductors in the CSTMT inversions (TE+TM) truly extend to the depth at which they are modeled, or if they in deeper parts are artificial effects of regularisation in the inversion cannot be said for sure. Accounting for the low frequencies utilised in the TE mode, one has very strong arguments that the deep conductors seen in the CSTMT model are true.</p><p>The TE-mode models have shown to be much less affected by the complex problems of near field effects in comparison with the TM-mode models. The evidence of the near field effects is very prominent in the TM-mode phase, but in the phase of the TE-mode one can not see any such tendencies. However, one can see a discontinuity in the same part of three profile lines which shows that the data is disturbed but not nearly as much as in the TM-mode. The apparent resistivity seems to be over all less affected by the near field effects. In the apparent resistivity of the TE-mode, one can not discern any near field effects at all.</p><p>In the TM-mode, the apparent resistivity shows higher apparent resistivity than the real apparent resistivity in the near field. To receive more information about the deeper structures, lower controlled source frequencies were allowed in the TE-mode than in the TM-mode inversion models. The RMS in the TE-mode inversions has not been deteriorated, which is an another indication that the TE mode is not very disturbed by the near field effects.</p><p>The RMT inversion models are shown to be heavily biased in the deeper parts to which the RMT data are insensitive and regularization determining the outcome of the inversion. One can also see that regularisation is influencing the whole inversion model. In the shallow subsurface the inversion models should be same for CSTMT and RMT, but one can see differences in resistivity between the models.</p><p>The real induction arrows show features that are not as clearly displayed in either the phase or apparent resistivity. It seems that the real induction arrows are better at detecting lateral differences in conductivity in a more resistive media, than the phase and apparent resistivity.</p>
19
Oskooi, Behrooz. "A Broad View on the Interpretation of Electromagnetic Data (VLF, RMT, MT, CSTMT)." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4146.
Full textAbstract:
<p>The resolution power of single Very Low Frequency (VLF) data and multi-frequency Radiomagnetotelluric (RMT) data in delineating conductive structures typical for the sedimentary cover and crystalline basement in Scandinavia is studied with a view to future developments of the technique to increasing the frequency range into the LW radio band. Airborne and ground VLF data are interpreted and correlated with RMT measurements made on the ground to better understand the resolution power of VLF data. To aid in this understanding single and multifrequency VLF and RMT responses for some typical resistivity structures are analyzed. An analytic model is presented for obtaining unique transfer functions from measurements of the electromagnetic components on board an air-plane or on the ground. Examples of 2D inversion of ground and airborne VLF profiles in Sweden are shown to demonstrate the quantitative interpretation of VLF data in terms of both lateral and depth changes of the resistivity in the uppermost crust.</p><p>Geothermal resources are ideal targets for Electromagnetic (EM) methods since they produce strong variations in underground electrical resistivity. Modelling of Magnetotelluric (MT) data in SW Iceland indicates an alteration zone beneath the surface, where there are no obvious geothermal manifestations, in between Hengill and Brennisteinsfjoll geothermal systems. It suggests that a hydrothermal fluid circulation exists at depth. It also proves that the MT method, with its ability to map deep conductive features can play a valuable role in the reconnaissance of deep geothermal systems in active rift regimes such as in Iceland.</p><p>A damped nonlinear least-squares inversion approach is employed to invert Controlled Source Tensor MT (CSTMT) data for azimuthal anisotropy in a 1D layered earth. Impedance and tipper data are inverted jointly. The effects of near-surface inhomogeneities are parameterized in addition to each layer parameter(s). Application of the inversion algorithm to both synthetic and field data shows that the CSTMT method can be used to detect azimuthal anisotropy under realistic conditions with near surface lateral heterogeneities.</p>
20
Singh, Paritosh. "Processing, inversion, and interpretation of 9C-3D seismic data for characterizing the Morrow A sandstone, Postle Field, Oklahoma." Thesis, Colorado School of Mines, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3559234.
Full textAbstract:
<p> Detection of Morrow A sandstones is a major problem in the exploration of new fields and the characterization of existing fields because they are very thin and laterally discontinuous. The present research shows the advantages of S-wave data in detecting and characterizing the Morrow A sandstone. Full-waveform modeling is done to understand the sandstone signature in P-, PS- and S-wave gathers. The sandstone shows a distinct high-amplitude event in pure S-wave reflections as compared to the weaker P- and PS-wave events. Modeling also helps in understanding the effect of changing sandstone thickness, interbed multiples (generated by shallow high-velocity anhydrite layers) and sidelobe interference effect (due to Morrow shale) at the Morrow A level. </p><p> Multicomponent data need proper care while processing, especially the S-wave data which are aected by the near-surface complexity. Cross-spread geometry and 3D FK filtering are effective in removing the low-velocity noise trends. The S-wave data obtained after stripping the S-wave splitting in the overburden show improvement for imaging and reservoir property determination. Individual P- and S-wave attributes as well as their combinations have been analyzed to predict the A sandstone thickness. A multi-attribute map and collocated cokriging procedure is used to derive the seismic-guided isopach of the A sandstone. </p><p> Postle Field is undergoing CO<sub>2</sub> flooding and it is important to understand the characteristics of the reservoir for successful flood management. Density can play an important role in finding and monitoring high-quality reservoirs, and to predict reservoir porosity. prestack P- and S-wave AVO inversion and joint P- and S-wave inversion provide density estimates along with the P- and S-impedance for better characterization of the Morrow A sandstone. The research provides a detailed multicomponent processing, inversion and interpretation work flow for reservoir characterization, which can be used for exploration in other parts of the world as well.</p>
21
Wei, Li. "Processing and Interpretation of Three-Component Borehole/Surface Seismic Data over Gabor Gas Storage Field." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1441043179.
Full text
22
Fanka, Walter Roye Taju. "Well Log and Seismic Data Interpretation : Rock Physics Study of Poorly Consolidated Sandstones in The North Sea." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18608.
Full textAbstract:
We use rock physics models for poorly consolidated rocks to diagnose reservoir sandstones in the Alvheim Field, North Sea. Geological factors that will control the rock physics and seismic properties include clay content, sorting, diagenesis, mineralogy, and bedding configuration. The various geologic factors will affect the fluid and stress sensitivity in these rocks. We investigate the interrelationships between various geological factors and seismic fluid and stress sensitivity, by combining well log data and rock physics models. Finally, we determine inter-well characteristics in terms of varying geological factors at different locations and discuss the results in terms of expected seismic signatures in the area.
23
Birken, Ralf Andreas. "Neural network interpretation of electromagnetic ellipticity data in a frequency range from 1 kHz to 32 MHz." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282407.
Full textAbstract:
A new real-time in-field interpretation and visualization scheme and software, using neural networks for the detection and localization of buried waste, and the boundaries of waste sites, has been developed. The capabilities and limitations of the high-frequency (1 kHz to 1 MHz and 31 kHz to 32 MHz) electromagnetic ellipticity systems are analyzed by numerically studying the sensitivity of the acquired 3D-ellipticity to model parameters describing the geometry of the systems and the electrical parameters of layered-earth models. Changes in ellipticity due to coil misalignment in standard operating mode are typically just 1% to 2%. Changes due to variations in layered-earth model parameters (resistivity, relative dielectric constant, and thickness) are typically at least one order of magnitude higher. Hence, it will be possible to resolve these parameters. For conductive models (resistivity < 50 Ωm) it will be hard to determine the relative dielectric constant and for models with high relative dielectric constants it will be hard to determine the resistivity, especially if it is greater than 1000 Ωm. The results of the sensitivity analysis contribute considerably to the training of several neural networks to determine the electrical properties of the subsurface. The two classes of artificial neural network paradigms utilized in this study are the radial basis function and the modular neural network algorithms. One-dimensional layered-earth inversions are performed by neural networks using ellipticity data. The three-dimensional localization of metallic objects (e.g. drums) is done by visualizing the results of one particular halfspace neural network technique. Several small conductive objects have been detected by applying this technique to data collected in controlled physical modeling field experiments. Classification neural networks are trained on field data to categorize ellipticity soundings into either a target or a background class. Two environmental geophysics field case studies were analyzed using the developed interpretation system and the visualization software. The first case study involves mapping subsidence areas caused by an underground coal mine fire in Wyoming. The neural network interpretations from the mine survey match comparable inversion results. The second study documents the successful characterization of a simulated hazardous waste pit at the Idaho National Engineering Laboratory.
24
ROY, NILANJAN. "ANALYSIS AND INTERPRETATION OF 2D SEISMIC DATA OVER THE ANCONA GAS STORAGE FACILITY, ILLINOIS, USING PETREL VISUALIZATION SOFTWARE." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1229924769.
Full text
25
Butterfield, Andrei. "Characterization of a Utica Shale Reflector Package Using Well Log Data and Amplitude Variation with Offset Analysis." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1401462908.
Full text
26
Sabor, Kawtar. "Couplage de mesures géophysiques pour la reconnaissance des digues en terre : application du data mining." Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS089.
Full textAbstract:
En France, EDF exploite plus de 500 km de digues de canaux qui alimentent les ouvrages hydroélectriques exploités. Dans le cadre de la réglementation sur la sûreté hydraulique et des travaux de confortement menés sur les ouvrages hydrauliques en terre, plusieurs méthodes de suivi sont utilisées allant de l’inspection visuelle et la recherche d’archives, aux mesures géotechniques in-situ et aux laboratoires. Les mesures géotechniques sont toutefois destructives pour l’ouvrage et offrent une information ponctuelle localisée concernant la portion prospectée ce qui a motivé le recours aux mesures géophysiques. Ces mesures sont utilisées pour caractériser de manière « quasi-continue » des linéaires importants d’ouvrages tout en préservant leur état grâce au caractère « non-destructif » de ces méthodes. EDF travaille donc sur l’utilisation de méthodes géophysiques pour la reconnaissance et la surveillance de ses ouvrages. Toutefois, l’interprétation des profils géophysiques est subjective et dépend de la connaissance de la personne qui la réalise à cause du lissage introduit par l’inversion dans ces profils. Pour pouvoir utiliser les résultats de ces méthodes dans un cadre réglementaire, il faut donc connaître leurs limites d’utilisation et objectiver les interprétations des résultats des inversions. Ce qui nous ramène au présent travail de thèse. Dans le cadre de mon travail, je propose une approche d’interprétation automatiques des profils inversés en utilisant un algorithme de clustering issu du data mining. Cette approche est aussi utilisée pour coupler différentes mesures géophysiques afin d’améliorer les interprétations en tirant profit des sensibilités des différentes méthodes. Pour définir la démarche d’application du clustering en géophysique et vérifier la faisabilité de cette approche pour l’interprétation des mesures géophysiques, j’ai suivi une méthodologie de validation qui consiste à appliquer mon approche sur des modèles synthétiques pour ensuite la tester sur des données de terrain issues d’une campagne multiphysique que j’ai réalisée pendant ma thèse. Les différentes étapes de validation m’ont permis de mettre en place une méthodologie d’application du clustering pour interpréter les mesures géophysiques mais aussi soulever de nouvelles questions qui pourront être traitées en perspectives de mon travail<br>In France, EDF (electricity of France) operates more than 500 km of dykes that are part of its hydroelectric power plants. The water in the stream is diverted into an open channel bordered by earthen dykes. Within the framework of the regulations on hydraulic safety and the reinforcement work carried out on hydraulic structures, several monitoring methods are used, ranging from visual inspection and archive research to in-situ geotechnical measurements and laboratories. However, geotechnical measurements are destructive to the structure and provide localized point information about the prospected portion, which is why geophysical measurements were used. These measurements are used to characterize in a "quasi-continuous" way important linear structures while preserving their state thanks to the "non-destructive" nature of these methods. EDF thus works on the use of geophysical methods for the recognition and the monitoring of its structures. However, the interpretation of the geophysical profiles is subjective to the knowledge of the person who interprets it because of the smoothing introduced by the inversion. To be able to use the results of these methods in a regulatory framework, it is therefore necessary to know their limits of use and to objectify the interpretations of the inversion results. This brings us back to the present thesis work. In the framework of my work, I propose an approach of automatic interpretation of inverted profiles using a clustering algorithm from data mining. This approach is also used to couple different geophysical measurements in order to improve the interpretations. In order to define the approach to apply clustering in geophysics and to verify the feasibility of this approach for the interpretation of geophysical measurements, I followed a validation methodology which consists in applying my approach on synthetic models and then testing it on field data from a metaphysical measurements campaign that I carried out during my thesis. The different steps of validation allowed me to set up a methodology of application of clustering to interpret the geophysical measurements but also to raise new questions which must be treated in the perspectives of my work
27
Lo, Re Davide. "Constraining potential field interpretation by geological data: examples from geophysical mapping, inverse and forward modelling." Tesi di dottorato, 2017. http://www.fedoa.unina.it/12164/1/Lo_Re_PhD_Thesis.pdf.
Full textAbstract:
In this thesis three different strategies in potential field data interpretation were implemented and studied. The strategies are related to map transformation, inversion and forward problem. The thesis aims at obtaining geophysical outputs with geological-like features. These kinds of outputs are a significant key to make it easier the geological interpretation of the geophysical data modelling. In particular, the outputs obtained by the different strategies will tend to highlight different units with distinct boundaries and represented by fairly constant field or physical property values.
A map transformation technique (terracing) is first proposed. It is based on the use of a cluster analysis technique applied to a gravity or pole-reduced magnetic map. The centre values of the clusters and the cluster number are selected by a statistical analysis of the data map. The use of cluster technique breaks the continuous function (potential field map) onto different areas characterized by piecewise constant values (terraces). The homogeneity within each area is preserved and this kind of feature allow an easy computation of an apparent physical property horizontal distribution map, directly comparable with a geological map. Tests on synthetic and real data are shown.
The inversion is treated by applying a strategy made up by three steps. The first and the last steps are inversions with different constraints and associated weights, the second one is conducted by clustering the output of the first smooth inversion. The strategy allows obtaining, in the final step, a volume where the retrieved physical property is classified (by clustering technique) in different volumes of relatively constant values, easily relatable to different geological units. The number of the units, as well as the physical property values associated to each unit, it has to be fixed a priori according to the geological knowledge of the area. Tests on synthetic and real data show that the final obtained models are valid in both geophysical (honoring the data) and geological (understandable relationships among clearly-defined geological units) points of view.
A forward problem solver procedure, based on iterative stochastic process is finally proposed. The solution is represented by surfaces that bound different layers having different physical properties. The anomaly field produced by the surfaces is computed by an algorithm working in a Fourier domain. According to the Markov chain simulation, at each iteration several surfaces are created and the best one is selected to be a starting model in the next iteration. The best model selection is performed according to the value of a goodness coefficient. A synthetic case is shown, and the final model obtained shows a possible shape of different bodies, with homogeneous physical property distribution, able to produce a field that adequately match an observed anomaly field.
28
Mantilla, Pimiento Adriana Maria [Verfasser]. "Crustal structure of the southwestern colombian caribbean margin : geological interpretation of geophysical data / von Adriana Maria Mantilla Pimiento." 2008. http://d-nb.info/989353834/34.
Full text
29
Budiman, Indra. "Interpretation of gravity data over central Jawa, Indonesia." Thesis, 1991. http://hdl.handle.net/2440/110285.
Full textAbstract:
This thesis aims to establish the correlation between gravity data and volcanic structure in Central Jawa, Indonesia. The study provides information on the major boundary which separates the Eocene sediment in the south from the younger sediment in the north. The results of this research may offer a better understanding of the major structural elements of island arcs.<br>Thesis (M.Sc.) -- University of Adelaide, Dept. of Geology and Geophysics, 1995?
30
Knoll, Edward Tyler. "Crustal deformation across the Galicia Bank of offshore Iberia from seismic reflection data: Processing, interpretation, and reconstruction." Thesis, 2002. http://hdl.handle.net/1911/17518.
Full textAbstract:
The Iberia Margin is an excellent example of a passive rift. Multi-Channel Seismic (MCS) data consisting of the Line 14 reflection profile from the 1997 Iberia Seismic Experiment were processed and interpreted. Enhanced processing attenuated pervasive water-bottom multiple noise. MCS data image an extensional terrain that includes the Ocean-Continent Transition (OCT). The Moho is imaged locally. Extended crust was restored to an unextended state to quantify deformation. Horizontal strain tends to increase seaward along dip; the average strain is 46%. Crustal-thickness data indicate an average crustal thickness of 9.9 km. With certain assumptions regarding the observability of extension, the presence of 'pure shear' exclusively, and initial crustal thickness, there is a major discrepancy between the observed average crustal thickness and the average crustal thickness predicted by observed strain. The only satisfactory explanation is that crust has been removed by asymmetrical extension (simple shear).
31
Unger, Michael Rhodes. "Structural and tectonic interpretation of deep seismic reflection data offshore Spain and Portugal: A tectonic rifting model." Thesis, 2001. http://hdl.handle.net/1911/17474.
Full textAbstract:
A portion of new seismic reflection/refraction data collected over the Iberia margin were processed and interpreted, resulting in the recognition of two previously unknown normal faults in the deep crust. These faults, named Q and R, formed during the Triassic-Cretaceous rifting of Pangea, and formation of the Atlantic basin. Previous studies have shown a third surface, the low-angle S reflector, in the area. S has previously been interpreted as a detachment surface or as a velocity interface. A model is proposed where extension was accommodated along Q, R and S during the rifting of Pangea. R and S acted as detachment surfaces as the hangingwall block moved westward. Late in the rifting process, the geometry of R and S was altered by motion of underlying serpentinized mantle material. This upwelling of the mantle controlled the shape of Sin three dimensions. Total extension across the margin is estimated at 1.67.
32
Halliday, Julie. "Shallow gas hazards in Queen Charlotte Basin from interpretation of high resolution seismic and multibeam data." Thesis, 2008. http://hdl.handle.net/1828/1312.
Full textAbstract:
This thesis investigates shallow gas hazards in Queen Charlotte Basin, a sedimentary basin situated offshore British Columbia. The work presented here provides the first detailed gas hazard assessment in Queen Charlotte Basin and the first evidence that gas has migrated from basin sediments into surficial sediments to be expelled in the water column.
A unique method of geophysical surveying is used to investigate hazards due to shallow gas at two sites within Queen Charlotte Basin: high-resolution multichannel seismic, Huntec Deep-Towed Seismic and multibeam bathymetry data were collected over two 2-D grids and interpreted concurrently to yield a comprehensive understanding of the geology at each site. Numerous features related to both ice-cover and shallow gas has been identified. Pockmarks, iceberg ploughmarks and seafloor mounds are observed in the multibeam data; acoustically turbid and vertical blank zones are imaged in the Huntec data and faulted anticlines containing bright spots as well as low frequency shadow zones are seen in the multichannel data.
Combining and interpreting all three geophysical datasets concurrently provided the means to discriminate features related to ice-cover from features related to gas in the shallow sediments. In addition, this method of geohazards assessment has enabled links between surficial and basin geology to be made. Based on the results obtained gas and other geohazards were identified at each of the two sites. Based on observations in high-resolution multichannel seismic data, gas is determined to have migrated along structural pathways within basin sediments and into surficial sediments. The level of hazard posed by shallow gas has been assessed qualitatively for each of the two study sites and gas hazard regions have been identified elsewhere in Queen Charlotte Basin.