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Ahmed, Zubair. "Rock Physics Characterization using Physical Methods on Powders." Thesis, Curtin University, 2018. http://hdl.handle.net/20.500.11937/75690.
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This study describes a detailed investigation of quantifying key micro-structural parameters of the unconsolidated granular media and their relationship with the grain shape factors calculated from micro-CT images. These parameters are combined with the contact based effective medium models to calculate the elastic properties of the constituent grains after utilising stress dependent ultrasonic velocities of the samples. Thus developed techniques produce good results for mono-mineral quartz sands and one of the poly-mineral rock powder.
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Zhang, John Jianlin. "Time-lapse seismic surveys, rock physics basis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ65147.pdf.
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DIAS, JONATAN DE OLIVEIRA. "ROCK PHYSICS MODELING EVALUATION FOR CARBONATE RESERVOIRS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36561@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
Desde a década de 80, abordagens data-driven têm sido utilizadas para identificação de fluidos e caracterização de reservatórios carbonáticos e siliciclásticos principalmente em relação à análise das amplitudes sísmicas. No entanto, técnicas aplicadas com sucesso para rochas siliciclásticas, como por exemplo: Análise AVO, inversões sísmicas e IDH (Indicadores Diretos de Hidrocarbonetos) revelaram não obter o mesmo êxito para reservatórios carbonáticos heterogêneos. Em contrapartida, diversos artigos mostram que fluxos de caracterização de reservatórios com modelos de física de rochas incorporados têm alcançado grande sucesso para obtenção de propriedades petrofísicas e atributos elásticos de ambas as rochas, utilizando sísmicas e well logs, em uma abordagem model-driven, focada nas características microestruturais do reservatório. Dessa forma, levando em consideração a importância de se utilizar modelos de física de rochas no escopo da caracterização de reservatórios, dois modelos de física de rochas - Xu e Payne e T-Matrix - foram aplicados, comparados e seus parâmetros foram estocasticamente avaliados e otimizados em um arcabouço Bayesiano. Através dessa abordagem, foi possível estimar, de uma forma confiável, os atributos elásticos de um reservatório carbonático (coquinas) levando em consideração diversos tipos de incertezas. Além disso, após a calibração e validação de ambos os modelos de física de rochas para diferentes poços, análises de sensibilidade foram realizadas para compreensão de forma quantitativa do comportamento dos atributos elásticos das coquinas em relação às alterações do conteúdo mineralógico, tipos de poro e fluidos desse reservatório.
Since the 80 s, data-driven approaches have been used for fluids identification and reservoir characterization of siliciclastic and carbonate rocks mainly regarding seismic amplitudes analyses. However, techniques successfully applied for siliciclastic rocks, such as: AVO analysis, seismic inversions and DHI (Direct Hydrocarbon Indicators) ranking revealed not have achieved the same outstanding and reliable results for heterogeneous carbonate rocks. On the other hand, several articles demonstrate that reservoir characterization workflows with rock physics models embedded have been reaching a robust success in order to obtain petrophysical properties and elastic attributes of both rocks, from the seismic and well logs, in a model-driven approach focused on the reservoirs microstructural information. In this way, taking into account the importance of applying rock physics models in the scope of reservoir characterization, two rock physics models - Xu and Payne and T-Matrix - were applied, compared and their parameters were stochastically evaluated and optimized in a Bayesian framework. Through this approach, it was possible to estimate, in a reliable manner, the elastic attributes of a carbonate reservoir (coquinas) taking into consideration different kinds of uncertainties. Furthermore, after the calibration in the well location and validation of both rock physics models for other wells, sensitivity analyses were conducted in order to quantitatively understand how the coquinas elastic attributes behave regarding the variations in the reservoir mineralogical content, pore shapes and fluids.
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Hoang, Phuong. "Rock physics depth trend analysis using seismic stacking velocity." Thesis, Norwegian University of Science and Technology, Department of Petroleum Engineering and Applied Geophysics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1631.
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Quantitative seismic interpretation is becoming more and more important in exploration and characterization of petroleum reservoirs. In this technology, rock physic analysis combined with seismic attributes has become a key strategy.
Nature creates inhomogeneous anisotropic rocks where the rock physics properties vary at different positions and directions. It is important to analyze and quantify the property changes as a function of depositional and burial trends in order to improve our detectability of petroleum reservoirs from seismic data.
In this thesis, we have presented a new methodology to obtain rock physics properties as a function of burial depth, i.e., rock physics depth trends (RPDTs), from well log and seismic data. To obtain RPDTs, several authors have suggested using rock physics models calibrated to well log data or constrained by diagenetic models. We present an alternative way to extract these from seismic stacking velocities. This is the main focus of the thesis.
We apply our methodology to extract RPDTs from seismic stacking velocities in the Njord Field area, located in the Norwegian Sea. We find that the seismic interval velocity trend matches nicely to the sonic velocity at the well location, especially above Base Cretaceous. By combining empirical RPDTs with seismic RPDTs, we are able to interpret and quantify the rock properties of different rock physics events that have occurred in Njord Field at well location and in the areas without well log information.
In this thesis we have successfully demonstrated how stacking velocities can be used to improve our understanding about normal mechanical compaction trends, tectonic activity and diagenetic events. This information is important for improved overburden and reservoir characterization, especially in areas with sparse or no well log data.
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Beloborodov, Roman. "Compaction Trends of Shales: Rock Physics and Petrophysical Properties." Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/68259.
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Shale is the most abundant and the least known type of sedimentary rock. It is found in every basin associated with hydrocarbon depositions and is notorious for its complicated properties. This thesis is dedicated to investigation of the compaction trends of rock physics and petrophysical properties of shale. It is supplemented with in-depth analysis of shale microstructure as a key parameter controlling the macroscopic anisotropic properties of shale.
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Rimstad, Kjartan. "Bayesian Seismic Lithology/Fluid Inversion Constrained by Rock Physics Depth Trends." Thesis, Norwegian University of Science and Technology, Department of Mathematical Sciences, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9772.
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In this study we consider 2D seismic lithology/fluid inversion constrained by rock physics depth trends and a prior lithology/fluid Markov random field. A stochastic relation from porosity and lithology/fluid to seismic observations is established. The inversion is done in a Bayesian framework with an approximate posterior distribution. Block Gibbs samplers are used to estimate the approximate posterior distribution. Two different inversion algorithms are established, one with the support of well observations and one without. Both inversion algorithms are tested on a synthetic reservoir and the algorithm with well observations is also tested on a data set from the North Sea. The classification results with both algorithms are good. Without the support of well observations it is problematic to estimate the level of the porosity trends, however the classification results are approximately translation invariant with respect to porosity trends.
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Spikes, Kyle Thomas. "Probabilistic seismic inversion based on rock-physics models for reservoir characterization /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Wisman, Putri Sari. "Rock physics changes due to CO2 injection : the CO2CRC Otway Project." Thesis, Curtin University, 2012. http://hdl.handle.net/20.500.11937/737.
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The CO2CRC Otway Project aims to demonstrate that CO2 can be safely stored in a depleted gas field and that an appropriate monitoring strategy can be deployed to verify its containment. The project commenced in 2005, with the baseline 3D seismic collected early in January 2008. CO2 was injected into depleted gas reservoir known as Waarre-C at Naylor field in April 2008. The first monitor survey was recorded in January 2009, shortly after the injection of 35,000 tonnes of CO2. Early predictions in the program suggested that the resulting time-lapse seismic effect will be very subtle because of the reservoir depth, small area, complexity, small amount of CO2/CH4 in 80/20 ratio injected and most of all partial saturation of the reservoir sand. The key challenge than presented to this research was how subtle exactly is the effect going to be? To answer that question I had to develop a workflow that will produce very accurate prediction of the elastic property changes in the reservoir caused by CO2 injection. Then the sensitivity of time-lapse seismic methodology in detecting subtle changes in the reservoir is investigated.The rock physics model I propose uses the “effective” grain bulk modulus (Kgrain) to represent the average mineralogy of the grains. The validity of this approach is confirmed by good agreement achieved between Vpsat core with Vpsat computed from the log data using the “effective” modulus. . The use of “effective” Kgrain was further justified by petrographic analysis. This has increased the modelling precision and changed the predicted time-lapse effect due to CO2 injection from 3% as an average over the reservoir sequence as previously computed to nearly 6%. The significance is that 6% change could be detected with high precision monitoring methodologies. The in-situ saturation type is homogeneous, according to the analysis path assumed in this thesis. If some patchiness exists in the reservoir it will be away from the wells and it would further elevate CO2 related seismic effect.The time-lapse seismic methodology at Otway site utilised very high survey density in order to increase sensitivity. On the negative side, weak sources and the change of the source type between the surveys resulted in non-repeatability greater or of the similar order as the time-lapse signal were expected to be. Hence the interpretation of the time-lapse P-wave seismic data assumed somewhat different path. I used the model-based post-stack seismic acoustic inversion in a similar way that history matching is used in reservoir simulation studies. I performed successive fluid substitutions, followed by the well ties and inversions. The objective was to look into the inversion error. Then the modelled fluid saturation case that result in minimal inversion error reflects the most likely state of the reservoir. Modelling using 35,000 tonnes of CO2/CH4 mix with 35% water saturation and 65% CO2/CH4 mix produced the smallest error when reinstating logs to the 2009 reservoir state.The time-lapse anomaly observed in the data exceeds predictions derived through the rock physics model, seismic modelling and simulation models. This is likely to be the case in general as the effect of CO2 onto a reservoir is difficult to predict. A “conservative” approach may result in an under-prediction of time-lapse seismic effects. Consequently, the predicted and measured seismic effects can be used as the lower and the upper bound of the time-lapse effects at Naylor field, respectively. The method presented here for analysis of a subtle time-lapse signal could be applied to the cases with similar challenges elsewhere.
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Cauchefert, Matthieu. "Rock Physics Properties of Artificial Shales: Effect of Organic Matter Characteristics." Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/81045.
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The objective of this project is to evaluate the influence of an array of organic matter characteristics on the physical properties (elastic and dielectric) of artificial organic-rich shales. We found evidence of the impact of the following variables: thermal maturity, kerogen type, organic particles texture and deposition method. The achievements of this study are also technical. We designed an advanced compaction cell recording petrophysical and elastic properties during consolidation and an artificial thermal maturation equipment.
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Tomlinson, Simon Michael. "Computer simulation studies of rock-salt structured binary transition metal oxides." Thesis, University College London (University of London), 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264941.
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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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Said, Dhiya Mustafa Mohamed. "Reservoir geophysics of the Clyde field : the development and application of quantitative analysis techniques." Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327396.
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Ohta, Yusuke. "Development of Resource Evaluation Technology by Integration of Geophysical Exploration Data and Rock Physics." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263636.
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Werthmüller, Dieter. "Bayesian estimation of resistivities from seismic velocities." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/8932.
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I address the problem of finding a background model for the estimation of resistivities in the earth from controlled-source electromagnetic (CSEM) data by using seismic data and well logs as constraints. Estimation of resistivities is normally done by trial-and-error, in a process called “inversion”, by finding a model of the earth whose responses match the data to within an acceptable error; what comes out of the inversion is what is put into the model by the geophysicist: it does not come out of the data directly. The premise underlying this thesis is that an earth model can be found that satisfies not only the CSEM data but also the seismic data and any well logs. I present a methodology to determine background resistivities from seismic velocities using rock physics, structural constraints, and depth trends. The physical parameters of the seismic wave equation are different from those in the electromagnetic diffusion equation, so there is no direct link between the governing equations. I therefore use a Bayesian framework to incorporate not only the errors in the data and our limited knowledge of the rock parameters, but also the uncertainty of our chosen and calibrated velocity-to-resistivity transform. To test the methodology I use a well log from the North Sea Harding South oil and gas field to calibrate the transform, and apply it to seismic velocities of the nearby Harding Central oil and gas field. I also use short-offset CSEM inversions to estimate the electric anisotropy and to improve the shallow part of the resistivity model, where there is no well control. Three-dimensional modelling of this resistivity model predicts the acquired CSEM data within the estimated uncertainty. This methodology makes it possible to estimate background resistivities from seismic velocities, well logs, and other available geophysical and geological data. Subsequent CSEM surveys can then focus on finding resistive anomalies relative to this background model; these are, potentially, hydrocarbon-bearing formations.
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Alkaff, Mohammed Ali O. "Integration of depositional process modelling, rock physics and seismic forward modelling to constrain depositional parameters." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/110.
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Stratigraphic modelling parameters can be modified by generating synthetic seismic data from the stratigraphic model via integration of the stratigraphic model, rock physics and seismic forward modelling. Rock physics is used to convert geological parameters to elastic parameters. These are then used to generate synthetic seismic data via seismic forward modelling. Synthetic data is then compared with its corresponding observed data and the stratigraphic modelling parameters are modified based on the comparison results.
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Harris, Dustin Matthew. "A laboratory investigation into rock physics and fracture potential of the Woodford shale, Anadarko Basin, Oklahoma." Thesis, Kansas State University, 2017. http://hdl.handle.net/2097/35509.
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Master of ScienceDepartment of Geology
Abdelmoneam Raef
Matthew W. Totten
The Woodford shale in west-central Oklahoma is an organic and silica rich shale that is a prolific resource play producing gas and liquid hydrocarbons (Gupta et al., 2013). Unconventional shale wells are only producible due to modern hydraulic fracturing techniques. Production surveys from unconventional reservoirs show significant variability between wells and even between fracking stages (Kennedy, 2012). The production potential of a particular shale appears to be related to its brittleness and kerogen content "sweetness". Thus, brittleness analysis becomes important when choosing which shales to produce. A rocks brittleness index can be related directly to elastic properties derived from P- and S-wave velocities, as well as, its specific mineral makeup. This project's main focus is to determine the elastic rock properties that affect or relate to Woodford shale brittleness and how they relate to the rock's specific mineral makeup and kerogen content. Measurements to determine elastic properties, based on ultrasonic laboratory testing, were conducted on available Woodford cores. The estimated elastic moduli were evaluated via cross-plotting and correlation with a variety of rock properties. Elastic properties are of essential relevance to forward seismic modeling in order to study seismic response. Mineral makeup, determined via XRD and XRF analyses done by Kale Janssen (2017), was used to calculate a mineral-based brittleness index for comparison with the elastic moduli. Evaluation of the elastic moduli assisted in determining which elastic properties directly relate to the brittleness of the shales and, in turn, to geomechanical aspects. These properties were correlated with data from previous studies including mineral percentages, total organic content (TOC), and thermal maturity. These correlations were used to determine which elastic properties best predict a rock's brittleness index. The calculated brittleness was used to develop a brittleness index map of the Woodford Formation.
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Garba, Mohammed Ali. "Electrical Formation Factor of Beach Sands and Clay-sand Mixtures from Experimental and Digital Rock Physics." Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/59632.
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Electrical properties of rocks are important parameters for well-log and reservoir interpretation. However, laboratory measurements are time-consuming and difficult. I develop here a comprehensive and robust methodology to compute the electrical formation factor from digital images obtained by X-ray tomography, for clean and shaly sands. Key points of this study are finite size effects of the cubes used for computation, and comparison of trends (and not individual data) formed by laboratory-measured and computed properties.
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Dickey, Kira Ann. "Geophysical Investigation of the Yellowstone Hydrothermal System." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/84922.
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Yellowstone National Park hosts over 10,000 thermal features (e.g. geysers, fumaroles, mud pots, and hot springs), yet little is known about the hydrothermally active zones hundreds of meters beneath the features. Transient electromagnetic (TEM) soundings and 2D direct current (DC) resistivity profiles show that hydrothermal alteration at active sites have a higher electrical conductivity than the surrounding hydrothermally inactive areas. For that reason, airborne TEM is an effective method to characterize large areas and identify hydrothermally active and inactive zones using electrical conductivity. Here we present results from an airborne TEM survey acquired jointly by the U.S. Geological Survey and the University of Wyoming in November, 2016. We integrate resistivity from the airborne electromagnetic (EM) survey with research drillhole data and rock physics models to investigate the controls on electrical conductivity in the upper few hundreds of meters of the Yellowstone hydrothermal system. Resistivities in Yellowstone are the product of complex variations of lithology, temperature, salinity, clay content, and hydrothermal fluids. Results show that the main drivers in lowering the high resistivitiy of volcanic rocks are water saturation and hydrothermal alteration. Salinities are not significantly elevated in Yellowstone and temperature is not a first order affect.Master of Science
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Gunter, Jesse Z. "Mechanisms of the Wurtzite to Rock Salt Phase Transitions in Galium Nitride." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/880.
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We studied the wurtzite to rock salt phase transition in gallium nitride ( GaN ). Using the mapping algorithm of COMSUBS we found 435 possible mechanisms for this transition. We then used FIREBALL to do density functional theory calculations and found enthalpy barrier heights for the transition pathway. We used this to determine the mechanisms that are the most favorable for GaN. The most favorable mechanisms for GaN are those that break no bonds during the phase transition. The bond-preserving mechanisms involve bilayer sliding of (010) hexagonal plane in the plus or minus [100] hexagonal direction.
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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.
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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.
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Rydén, Gabriel. "Ab initio lattice dynamics and Anharmonic effects in refractory Rock-salt structure TaN ceramic." Thesis, Linköpings universitet, Teoretisk Fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-174208.
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Transition Metal Nitrides (TMN) are of considerable importance for the industry and have gathered a great deal of interest in the scientific community, mostly due to their unique physical and mechanical properties. To increase the understanding of what enables them to have such extraordinary properties requires the study of lattice dynamics and their phonon dispersion. In this thesis, the transition metal nitride, TaN, is studied extensively along with preliminary results for NbN. The primary tool for this investigation is simulations. Computational methods, such as ab initio Molecular Dynamics (AIMD) and the Temperature Dependent Effective Potential (TDEP) method are used to generate phonon spectra and to compute the lattice thermal conductivity. The results indicate that TaN crystal structure stabilizes dynamically at much lower temperatures than previously established with other methods. The average linear thermal expansion coefficient of TaN is a = 9.0 * 10-6 K-1, which is consistent with other TMN. The phonon-phonon lattice thermal conductivity of TaN follows a similar behaviour as for other TMN. Preliminary result for NbN suggests a behaviour at lower temperatures that are similar to that observed for TaN. However, further investigations are required to pinpoint TaN and NbN transition temperatures more exactly and include effects, such as electron-phonon scattering and isotope effects for a better estimation of the lattice thermal conductivity.
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Bonnelye, Audrey. "Etude des propriétés physiques et mécaniques des argilites : de la déformation en laboratoire aux failles naturelles." Thesis, Cergy-Pontoise, 2016. http://www.theses.fr/2016CERG0858.
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Les argilites, sont définies comme étant des roches comportant une large fraction de minéraux argileux. Leurs propriétés physiques et mécaniques présentent un intérêt pour l’étude du comportement hydro-mécanique des failles dans la partie supérieure de la croûte mais aussi pour la compréhension des roches couvertures de réservoirs d’hydrocarbures ou pour l’expertise de la pérennité du stockage de déchets radioactifs.Cette thèse propose deux approches afin de comprendre l’organisation de la déformation dans ce type de matériau, une première purement mécanique sur des échantillons intacts et la seconde s’intéressant aux propriétés physiques de matériaux déformés. Pour cela, nous avons étudié les argilites de Tournemire (Tunnel expérimental de l'IRSN, Aveyron, France).La première partie consiste en une série d’essais triaxiaux. Nous avons déterminé les enveloppes de rupture de trois groupes d’échantillons carottés avec des orientations différentes par rapport au litage (0°, 45°, et 90°). Pour chaque orientation, sept expériences ont été réalisées à différentes pressions de confinement (2.5, 5, 10, 20, 40, 80, 160 MPa). L’influence de la vitesse de déformation a été établie en comparant des expériences réalisées avec des vitesses de déformation différentes (10-7 s-1 et 10-5 s-1). Pendant les expériences, les vitesses d’ondes P et S ont été enregistrées selon différents angles par rapport au litage afin de quantifier l’évolution de l’anisotropie des propriétés élastiques.Cette partie permet de mettre en évidence l’importance de l’orientation du litage par rapport à la contrainte principale sur la résistance mécanique de nos échantillons. De plus, un modèle micromécanique basé sur le « wing crack » permet d’expliquer l’anisotropie mécanique de nos argilites par l’anisotropie de la ténacité KIC.Par ailleurs, on constate que l’évolution de l’anisotropie des propriétés élastiques dépend elle aussi de l’orientation considérée. Lors de la compression, l’orientation 90° présente d’importantes variations pouvant aller jusqu’à une inversion de l’anisotropie, alors que les vitesses n’évoluent que très peu pour l’orientation 0°. Ces variations ont été quantifiées par les paramètres de Thomsen. L’étude des vitesses élastiques et celle des microstructures, permettent de mettre en évidence l’importance des processus plastiques comme la réorientation des minéraux au cours de la déformation.La seconde partie consiste en une étude pétrophysique (vitesses des ondes P, ASM, densité, saturation, porosité) d’échantillons provenant d’un forage traversant une zone de faille. Le but est de quantifier la variation de ces propriétés à l’approche du cœur de faille.Un protocole d’échantillonnage et de mesure a été mis en place. Le protocole comporte une première série de mesures directement sur le terrain afin de s’affranchir des problématiques liées à la préservation des échantillons (notamment pour les mesures de porosité/densité/saturation). Par la suite, des échantillons ont été prélevés pour réaliser des mesures à la fois dans le cadre de cette thèse (vitesses des ondes P et ASM) mais aussi dans d’autres laboratoires (étude de la composition minéralogique, CT-scan).A partir des observations, on caractérise :• Une zone saine caractérisée par des échantillons ne présentant pas ou très peu de fracturation• Une zone endommagée qui présente un grand nombre de fractures calcifiées• Une zone de cœur caractérisée par une déstructuration totale (pas de bedding apparent) et des variations de couleur.Notre étude met en évidence une signature physique propre à chaque zone de cette faille avec notamment une diminution de l’anisotropie des échantillons en zone endommagée fortement marquée. De plus, des mécanismes de rotation de la stratigraphie similaires à ceux observés à l’échelle des microstructures lors de la déformation expérimentale ont été observésShales or clays are defined as rock having a large proportion of clay minerals. Their physical and mechanical properties are of interest for the study of the hydro-mechanical behavior of faults in the uppermost crust but also for the understanding of the cap rocks of hydrocarbon reservoirs or for the expertise of the durability of radioactive waste storage.This thesis proposes two complementary approaches to understand the organization of the deformation in this type of material, a first purely mechanical on undisturbed samples and the second focusing on the physical properties of deformed materials. During this thesis, we studied Tournemire shales (IRSN tunnel, Aveyron, France).The first part consists in triaxial tests. We determined the failure envelopes of three sets of core samples with different orientations with respect to bedding (0 °, 45 ° and 90 °). For each orientation, seven experiments were performed at different confining pressures (2.5, 5, 10, 20, 40, 80, 160 MPa). The influence of the strain rate was determined by comparing experiments with different strain rates extending over two orders of magnitude (between 〖10〗^(-7) s^(-1) and 〖10〗^(-5) s^(-1)). During the experiments, the P and S wave velocities were recorded from different angles with respect to the bedding to quantify the evolution of the anisotropy of the elastic properties according to the imposed stress.This section allows to highlight the importance of the orientation of bedding relatively to the principal stress applied on our samples. It is noted for example that the weakest orientation is 45 ° and 90 ° the strongest orientation. In addition, a micromechanical model based on the "wing crack" theory helps to explain the mechanical anisotropy of our argillites by the anisotropy of the fracture toughness K_Ic.Moreover, it is found that changes in the anisotropy of the elastic properties also depends on the bedding orientation. During compression, the 90 ° orientation has significant variations up to a reversal of the anisotropy, whereas the elastic wave velocities show little changes for 0 ° orientation. These variations were quantified by Thomsen parameters. The study of elastic velocities and of microstructures of our samples highlight the importance of the plastic processes such as reorientation of minerals during deformation.The second part consists of a petrophysical study (P wave velocities, ASM, density, saturation, porosity) of samples from a borehole drilled through a fault zone. The goal here is to quantify the variation of these properties as we approach the fault core.A protocol of sampling and measurement was established to realize a complete study of drillings. The protocol includes a first serie of measures directly in the field in order to overcome the problems linked to the preservation of samples (especially for porosity measurements / density / saturation). Subsequently, samples were taken for measurements both in the context of this thesis (P wave velocities and ASM), but also in other laboratories (study of the mineralogical composition, CT-scan).Three fault zones were identified from field observations:• An intact zone characterized by samples with no or very little fracturing• A damaged zone that includes a large number of calcified fractures• A fault core zone characterized by a complete breakdown (no apparent bedding) and color variations.Although these areas were determined on observation criteria, our study demonstrates an own physical signature for each zone of this fault with an important decrease in the anisotropy of the samples from fault core. In addition, bedding rotation with similar mechanisms to those observed at the microstructural scale during the experimental deformation was observed
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Steyn, Ruan. "Portable X-ray fluorescence and nuclear microscopy techniques applied to the characterisation of southern African rock art paintings." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86541.
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Thesis (MSc)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Non-destructive portable X-ray Fluorescence (pXRF) and Particle Induced X-ray Emission (PIXE) were used to measure the elemental concentration of rock art fragment paintings. For pXRF the Amptek Silicon Drift Detector (SDD) and Niton XL3t spectrometers were used to perform the measurements. These two spectrometers use different spectrum analysis methods. The Peak Deconvolution (PD) analysis method is used for the Amptek SDD and an Inverse Overlap Matrix (IOM) method is used for the Niton XL3t spectrometer. The pXRF methods were validated by using alloys, coins and rock standards. The validation is important to establish if the pXRF technique is properly understood and used and to advance the investigation to more complex rock art paintings, with heterogeneous and layered properties. The elemental concentrations obtained for the Standard Reference Materials (SRMs), which were used for the validation, were in good agreement with that of the known concentration of the SRMs. The two rock art fragments which were analysed from the Mount Ayliff and Ha Khotso caves were part of larger rock art painting prior to it being naturally exfoliated from the rock. For the Mount Ayliff rock art, seven paint points, two unpainted rock (varnish) point adjacent to the paint and the back of the rock were analysed. The colour of the paint ranged from black, shades of brown and shades of red. The black paint is due to manganese or charcoal. The red colour is due to iron oxide and the red-brown colour is due to Hematite (a type of ferrous oxide) [1]. For the Ha Khotso fragment the paint on the front of the rock and the rock substrate (back of the rock) were analysed. For the Mount Ayliff rock art fragment the results for both pXRF spectrometers indicated that the elemental concentration was uniform across the fragment. This is due to the formation of a uniform layer of minerals such as silica and calcium introduced by the seepage of water through the cracks of the cave. Therefore no correlation could be established between the colour of the rock art paint and the elements detected, as was found with the work done by Peisach, Pineda and Jacobson [1]. For the Ha Khosto rock fragment a relation between the Ca composition and the cream colour of the rock art paint was established. Both the PIXE and pXRF techniques were used to identify the compound concentrations of the Ha Khotso rock art fragment. The comparison between the two techniques highlights the complexity of rock art paint analysis. The results from the PIXE elemental mapping indicated the non-uniform distribution of the elements in the analysed region. From the rock art fragment measuring the analysed points 5 times and obtaining the same results, indicated that the particle size and inhomogeneities did not have much effect on the compound compositions. In order to obtain high accuracy results with pXRF, sound scientific methodology with specific knowledge and expertise, not only about the XRF technique, but also about the sample under investigation is required. For alloy analysis pXRF is well suited, the analysis of geological material however more complex, since they are composed predominately of low atomic elements e.g. silicon, aluminium, magnesium, sodium, oxygen and carbon – all of which are excited with very low efficiencies.
AFRIKAANSE OPSOMMING: Nie-beskadigended X-straal Fluoresensie (pXRF) en Deeltjie Geinduseerde X-straal emmissie (PIXE) was gebruik om die elementêre konsentrasie van die rotstekeninge in hierdie studie te bepaal. Vir die pXRF-tegniek is die “Amptek Silicon Drift Detector (SDD)” en die “Thermo Scientific Niton XL3t” spektrometers gebruik gemaak om die metings uit te voer. Die twee spektrometers maak gebruik van verskillende spektrum analiseringsmetodes.Die “Peak Deconvolution (PD)” analiseringsmetode is gebruik vir die “Amptek SDD” en die “Inverse Overlap Matrix (IOM)” analiseringsmetode is gebruik vir die “Thermo Scientific Niton XL3t” spektrometer. Vir die validasie van die pXRF-metode is van allooie, muntstukke en rots standaarded gebruik gemaak. Die validasie is belangrik om vas te stel of die pXRF tegniek behoorlik verstaan en gebruik word en om die ondersoek te bevorder na meer komplekse rotstekeninge, met heterogene en lae eienskappe. Die element konsentrasies wat vir die “Standard Reference Material (SRM)” wat gebruik is vir die validasie, was in 'n goeie ooreenkoms met die van die konsentrasie van die SRM, wat bekend is. Die twee rotstekeninge wat ontleed is van die Mount Ayliff en Ha Khotso grotte en was deel van 'n groter rots kuns skildery voordat hul natuurlik afgebreek het. Vir die Mount Ayliff rotskuns, is sewe verf punte, twee ongeverfde rots (vernis) punte aangrensend aan die verf en die agterkant van die rots ontleed. Die kleur van die verf het gewissel van swart, skakerings van bruin en skakerings van rooi. Die swart verf kan toegeskryf word aan mangaan of houtskool. Die rooi kleur is as gevolg van ysteroksied en die rooi-bruin kleur is as gevolg van Hematiet ('n tipe van yster oksied) [1]. Vir die Ha Khotso rotskuns is die verf aan die voorkant van die rots en die rots substraat (agterkant van die rots) ontleed. Vir die Mount Ayliff rotstekening het die resultate vir beide pXRF spektrometers aangedui dat die elementele konsentrasie uniform oor die rotstekening is. Dit is as gevolg van die vorming van 'n uniforme lagie van silica en kalsium, wat deur die sypeling van water deur die krake van die grot na die oppervlak van die rotstekening beweeg het. Daarom kon geen korrelasie tussen die kleur van die rotstekening en die elemente wat gemeet is bepaal word nie, soos gevind deur die werk van Peisach, Pineda en Jacobson [1]. Vir die Ha Khotso rotstekening is ‘n verband tussen die room kleur van die rotstekening verf en Ca konsentrasie gevind. Beide die PIXE en pXRF tegnieke is gebruik om die konsentrasies van die Ha Khotso rotstekening te identifiseer. Die vergelyking tussen die twee tegnieke beklemtoon die kompleksiteit van rotstekening verf analise. Die resultate van die PIXE elementele karakterisering het aangedui die nie-eenvormige verspreiding van die elemente in die ontlede area. Deur die meting van die ontlede punte 5 keer te herhaal, en dieselfde resultate verkry, is ‘n aanduiding dat die deeltjie grootte en inhomogeniteite nie veel invloed op die elementele konsentrasies het nie. Ten einde 'n hoë akkuraatheid resultate te kry met pXRF, moet goeie wetenskaplike metode toegepas word met spesifieke kennis en kundigheid, nie net oor die XRF tegniek, maar ook oor die rotstekening wat ondersoek word vereis. pXRF is wel geskik vir die ontleding van allooie, die ontleding van geologiese materiaal is egter meer kompleks, aangesien die materiaal hoofsaaklik bestaan uit lae atoomgetal elemente bv silikon, aluminium, magnesium, natrium, suurstof en koolstof - wat almal met lae doeltreffentheid opgewek en baie afgerem word in die materiaal.
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Mikkelsen, Espen Rødland. "Monitoring of CO2 Sequestration at the Longyearbyen CO2 Lab by Time-lapse Seismic : An Interdisciplinary Rock Physics Study." Thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9931.
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Abreu, Elita Selmara de. "Modelagens teóricas e empíricas aplicadas à investigação da conexão entre as propriedades petrofísicas e elásticas em rochas carbonáticas." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277090.
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Orientadores: Sandro Guedes de Oliveira, Lúcia Duarte DillonDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: O principal propósito dessa dissertação é estudar modelos de meio efetivo de física de rochas que conecte as propriedades petrofísicas e as propriedades elásticas, assim como a sua aplicação na investigação dessas propriedades em rochas carbonáticas. Inicialmente será feita uma introdução a alguns modelos de física de rochas para meio efetivo, conhecidos como modelo de Voigt-Reuss-Hill, modelo de Kuster & Toksöz, modelo Diferencial de Meio Efetivo e relação de Gassmann, com objetivo de estabelecer os parâmetros que serão medidos e utilizados no desenvolver do trabalho. Após essa parte introdutória, baseado no modelo de Xu-Payne, foram realizadas uma série de análises de atributos geométricos, como a distribuição de tipos de poros, obtidas através de lâminas petrográficas com intuito de descrever a correlação entre as propriedades petrofísicas e elásticas e assim poder calibrar o modelo teórico utilizado na predição dessas propriedades. Dessa forma, o modelo calibrado passa a desempenhar um papel mais condizente com o sistema poroso da rocha permitindo uma melhor correlação entre os parâmetros elásticos e petrofísicos. Os resultados obtidos mostram que a utilização da informação de lâminas petrográficas, na parametrização do modelo, torna o método mais robusto na predição e conexão das propriedades elásticas e petrofísicas de rochas carbonáticas, tornando confiável a mudança de escala rocha-perfil, bem como possibilitando a predição qualitativa de propriedade permo-porosas a partir da velocidade da rocha
Abstract: The main purpose of this dissertation is to study rock physics effective models that connect the petrophysics and elastic properties as well as its application on the investigation of these properties on carbonate rocks. Firstly, we make an introduction to some rock physics of effective models as: Voig-Reuss-Hill, Kuster&Toksöz, Differential Effective Medium, Gassmann¿s Relation, aiming at establishing the parameters that will be measured and used latter. After this introductory part and based on the Xu-Payne model, several geometric factors analysis was done like pore types distribution, obtained by thin sections, with the intention of describing the correlation between the petrophysics and elastic properties. In this way, the model becomes more compatible with the rock porous medium, allowing a better correlation between the petrophysics and elastic parameters. Our results show that using the thin section information on the model parametrization, the predictability and connectivity of petrophysics and elastic properties applied to carbonate rocks become more robust, making trustable the upscale rock-well log and also enabling the permo-porosity properties prediction, in a qualitative way, through the velocity measurements
Mestrado
Física
Mestra em Física
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Nazarova, Cherriere Marfa. "Wettability study through x-ray micro-ct pore space imaging in eor applied to lsb recovery process." Thesis, Pau, 2014. http://www.theses.fr/2014PAUU3030/document.
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La thèse a pour but d’étudier les effets de changements de mouillabilité de roches dans des conditions d’injections d’eau douce en tant que méthode de récupération d’hydrocarbures. Afin d’identifier le ou les mécanismes à l’origine du gain additionnel de récupération nous avons utilisé un microtomographe RX. Nous avons ainsi imagé les états de saturations finales d’un milieu poreux rempli de saumures et d’huiles. Une fois le drainage primaire réalisé nous avons effectué deux phases d’imbibitions : avec une saumure (récupération secondaire) puis une imbibition d’eau douce (récupération tertiaire). L’analyse de la mouillabilité à l’échelle du pore a permis de mettre en évidence l’effet de la température et de la salinité sur la mouillabilité. Nous avons montré que les changements de mouillages des roches n’étaient pas occasionnées par la seule expansion de la couche électrique en revanche des changements de mouillabilité ont été montrés. Ces changements s’expliquant par des transitions de mouillages de second ordre observées non seulement pour des gouttes d’huiles sur de l’eau mais également sur un substrat en verre. Au final, la mouillabilité en milieux poreux doit être mise en évidence à une échelle sous-Micrométrique ce qui est relativement nouveau dans le domaine pétrolierThe aim of the thesis is to study rock wettability change effects caused by Low Salinity brine injection as tertiary recovery method. To identify the underlying mechanism or mechanisms of additional oil recovery X-Ray imaging technology was applied. We have also imaged the end-Point saturations of filled by brine and water core samples. Once the primary drainage is realized we carried out two phases imbibitions: with high salinity brine (waterflooding) and with low salinity brine (tertiary recovery mode). The wettability analysis at pore scale permitted to put in evidence the thermal and saline effects playing a decisive role in rock wettability. We have showed wettability changes are not caused by only electrical double layer expansion, however wettability changes was shown. These changes are explained by wettability transition of second order and observed not only for oil droplet on brine, but also for oil deposited on glass substrate. Finally, the pore space wettability needs to be evidenced at sub-Micrometric scale that is new for the petroleum domain
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Eid, Rami Samir. "Numerical modelling of geophysical monitoring techniques for CCS." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/22049.
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I assess the potential of seismic and time-domain controlled-source electromagnetic (CSEM) methods to monitor carbon dioxide (CO2) migration through the application of a monitorability workflow. The monitorability workflow describes a numerical modelling approach to model variations in the synthetic time-lapse response due to CO2 migration. The workflow consists of fluid-flow modelling, rock-physics modelling and synthetic seismic or CSEM forward modelling. I model CO2 injected into a simple, homogeneous reservoir model before applying the workflow to a heterogeneous model of the Bunter Sandstone reservoir, a potential CO2 storage reservoir in the UK sector of the North Sea. The aim of this thesis is to model the ability of seismic and time-domain CSEM methods to detect CO2 plume growth, migration and evolution within a reservoir, as well as the ability to image a migrating front of CO2. The ability to image CO2 plume growth and migration within a reservoir has not been demonstrated in the field of CSEM monitoring. To address this, I conduct a feasibility study, simulating the time-lapse CSEM time-domain response of CO2 injected into a saline reservoir following the multi-transient electromagnetic (MTEM) method. The MTEM method measures the full bandwidth response. First, I model the response to a simple homogeneous 3D CO2 body, gradually increasing the width and depth of the CO2. This is an analogue to vertical and lateral CO2 migration in a reservoir. I then assess the ability of CSEM to detect CO2 plume growth and evolution within the heterogeneous Bunter Sandstone reservoir model. I demonstrate the potential to detect stored and migrating CO2 and present the synthetic results as time-lapse common-offset time sections. The CO2 plume is imaged clearly and in the right coordinates. The ability to image seismically a migrating front of CO2 remains challenging due to uncertainties regarding the pore-scale saturation distribution of fluids within the reservoir and, in turn, the most appropriate rock-physics model to simulate this: uniform or patchy saturation. I account for this by modelling both saturation models, to calculate the possible range of expected seismic velocities prior to generating and interpreting the seismic response. I demonstrate the ability of seismic methods to image CO2 plume growth and evolution in the Bunter Sandstone saline reservoir model and highlight clear differences between the two rock-physics models. I then modify the Bunter Sandstone reservoir to depict a depleted gas field by including 20% residual gas saturation. I assess the importance and implication of patchy saturation and present results which suggest that seismic techniques may be able to detect CO2 injected into depleted hydrocarbon fields.
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Queisser, Manuel Peter. "Quantitative monitoring of CO2 injection at Sleipner using seismic full waveform inversion in the time lapse mode and rock physics modeling." Paris, Institut de physique du globe, 2012. http://www.theses.fr/2012GLOB0001.
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Carbon capture and sequestration is a technology to achieve a considerable deceleration of CO2 emission promptly. Since 1996 one of the largest CO2 storage projects is taking place at Sleipner in the Norwegian North Sea. In order to monitor injected CO2, time lapse surface seismic monitoring surveys have been carried out. Estimating subsurface parameters from the Sleipner seismic data is a challenging problem due to the specific geology of the storage reservoir, which is further complicated by injected CO2. Most seismic imaging methods enable only qualitative insights into the subsurface. Full waveform inversion is well known in the seismic community but not well established yet. Presented results are mostly of demonstrative character. Applying full waveform inversion as an actual tool to a complex problem such as Sleipner is novel. Motivated by the need for a quantitative seismic monitoring of the injected CO2, I have applied 2D seismic full waveform inversion to seismic data sets from Sleipner from 1994 (baseline), 1999 and 2006 along three seismic lines to infer subsurface parameters and parameter changes in the storage reservoir. The P-wave velocity is the major parameter, as it is the most sensitive to CO2 injection. An energy preconditioning of the gradient has been implemented. The usual source wavelet calibration did not prove to be reliable. An alternative source calibration has been successfully applied. By comparing seismic images with inversion results, I found that using seismic images to locate CO2 accumulations in the subsurface may be misleading. The quantitative imaging approach using full waveform inversion resulted in a consistent evolution of the model parameter with time. Major reductions in Pwave velocity and hence the CO2 accumulations could be quantitatively imaged down to a resolution of 10 m. Observed travel time shifts due to CO2 injection are comparable to those derived from the inversion result. In order to estimate CO2 saturations, rock physical concepts have been combined and extended to arrive at a rock physical formulation of the subsurface at Sleipner. I used pseudo Monte Carlo rock physics modeling to assess the influence of lithologic heterogeneity on the CO2 saturations as well as to generate pseudo well logs to estimate confidence intervals of the inverted parameters. The rock physics modeling has been used to relate inverted parameters to CO2 saturations. The injected CO2 is buoyant. The highest CO2 saturations are in the upper half of the storage reservoir but not necessarily at the top. Non-uniqueness of the saturation maps associated with the density scenario has been assessed. As a result, the distribution of the maximum saturation values remains the same. The quantity of dissolved CO2 in the reservoir water is a key parameter from both a security and optimization point of view. A quantitative estimation of dissolved CO2 by seismic means has not been undertaken yet to our knowledge. Based on the seismic inversion result of a seismic line, I found that along the line at least 20% of the injected CO2 mass was dissolved in 2006, after 10 years of injection. Such a high value indicates enhanced solubility trapping, which is very advantageous for storage safety at Sleipner. The results of this work represent a further step towards ultimate goals of quantitative monitoring, such as the estimation of the injected CO2 in-situ volume.
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Al-Brithen, Hamad A. H. "Scanning Tunneling Microscopy Investigation of Rock-salt and Zinc-blende Nitrides Grown by Molecular Beam Epitaxy." Ohio University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1107274641.
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Jihui, Jia. "Microscopic and Macroscopic Characterization on Mechanical Properties of Gas Hydrate." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215521.
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Poston, Edward J. "Experimental Deformation of O+ Oriented Synthetic Quartz Single Crystals." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1491569717148234.
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Tönsing, Tobias R. "Using rock physics to determine uncertainties in pore-fluid and lithology-estimates from seismic attributes in the Bredasdorp Basin, offshore South Africa." Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/4227.
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This study is aimed at developing a workflow for quantitative seismic interpretation. The workflow generated probability maps of various facies and pore-fluid by combining seismic attributes and wireline log data through rock physics relationships and supervised statistical classification. The workflow was developed mainly for hydrocarbon exploration, but could be used for other purposes, provided the target is seismically detectible. Any prior regional geological knowledge is built into the workflow, by extending the training date appropriately. The workflow aims to maximize the extraction of quantitative geological parameters from data that are most commonly acquired for hydrocarbon exploration, namely seismic and wireline log data. The workflow is presented using 3D seismic data from the Bredasdorp Basin offshore South Africa's south-coast. Wireline log data from the E-BX1 borehole are also used in the study, as well as regional geological interpretations. The study focused on the siliciclastic Aptian "13B" sequence, which was encountered at a depth of 2500 m below sea level at borehole E-BX1. Two massive 13B sandstone units were encountered at E-BX1. The lower unit is 50 m, and the upper 20 m thick. Both are water wet. The results of this study suggest that there are two oil accumulations at the 13X level around E-BX1. This is indicated by the high probability predicted for oil-bearing sandstone in these two areas.
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Makarynska, Dina. "Theoretical and numerical modelling of the effect of viscous and viscoelastic fluids on elastic properties of saturated rocks." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/289.
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Rock physics is an essential link connecting seismic data to the properties of rocks and fluids in the subsurface. One of the most fundamental questions of rock physics is how to model the effects of pore fluids on rock velocity and density. Contemporary scientific computing allows geophysicists to conduct extremely complex virtual (computational) experiments on realistic digital representations of complex porous media, and thus directly relate the measurable properties of the media to their microstructure and saturation. Computational (digital) rock physics can also serve as an effective tool in examining new and existing rock physics models. The finite element method (FEM) has been proved effective in simulations of the linear elastic properties of porous rock under static conditions. In this thesis, FEM is used to study the effect of patchy saturation on elastic velocities of digital images of rocks. However, FEM belongs to a group of grid methods, and its accuracy is limited by discretization errors. This can cause errors in rock property predictions and needs to be thoroughly examined. In this thesis, a test scenario based on rigorous theories for grid-based methods such as FEM is developed, which allows establishing optimal computational parameters in terms of accuracy of the results and time cost of computations.Gassmann’s equations are the most widely used relations to predict velocity changes resulting from different pore fluid saturations. This problem is also known as fluid substitution. Despite the popularity of Gassmann’s equations and their incorporation in most software packages for seismic reservoir interpretation, important aspects of these equations such as sensitivity to microheterogeneity has not been thoroughly examined. In this thesis, the sensitivity of Gassmann’s equations to microheterogeneity is estimated for different quartz/clay porous mixtures using computational (FEM) simulations. The results of this study suggest that the accuracy of Gassmann’s fluid substitution remains adequate for a wide variety of highly porous rocks even if the contrast between the elastic properties of mineral constituents is large.While Gassmann’s fluid substitution is robust for rocks saturated with Newtonian fluids (brine, gas, light oil), it breaks down for viscoelastic fluids such as heavy oils. An alternative fluid substitution scheme for rocks saturated with viscoelastic fluids based on self-consistent effective medium theory is proposed in this thesis. Comparison with laboratory measurements shows that the scheme realistically estimates the frequency- and temperature dependent properties of heavyoil rocks and can be used for practical applications.A useful tool for modelling and estimation of properties of rocks with arbitrary or unknown microstructure are rigorous bounds on elastic moduli. The common elastic bounding methods such as Hashin-Shtrikman bounds are not applicable for heavy-oil rocks because of viscoelastic rheology of heavy oils. In this work, it is demonstrated that the viscoelastic bounding method of Milton and Berryman for the effective shear modulus of a two phase three-dimensional isotropic composite provides rigorous bounds for dispersion and attenuation of elastic waves in heavy-oil rocks. In particular, computation of these bounds shows that dispersion and attenuation in a rock saturated with a fluid (viscous or viscoelastic) can be much stronger than in the free fluid. This phenomenon is caused by wave-induced fluid flow relative to the solid. At sonic and ultrasonic frequencies, dispersion and attenuation appears to be dominated by the local (pore-scale) flow between pores of different shapes and orientations. The Mavko and Jizba expressions for the so-called unrelaxed frame bulk and shear moduli are one of the most popular quantitative models of squirt dispersion. However, these expressions are limited to liquidsaturated rocks and high frequency. In this thesis, The Mavko-Jizba relations are generalized to gas-saturated rocks. Furthermore, dispersion and attenuation is computed using a new squirt flow model, presented in this thesis. All the parameters in this model can be independently measured or estimated from measurements. The model gives complex frequency- and pressure-dependent effective bulk and shear moduli of a rock consistent with laboratory measurements.Variation of elastic properties of rocks with pressure is often modelled using penny-shaped or spheroidal cracks as idealization of real crack/pore geometry. In this doctorate, the validity of this approach is analysed by extracting the ratios of shear to bulk stress sensitivity coefficients, and normal to tangential compliances from ultrasonic measurements on a number of dry sandstone samples. The ratios show large scatter and, for a large number of dry sandstone samples, are not consistent with spheroidal crack theory. This inconsistency results in significantly different estimates of crack density from bulk and shear moduli, and in deviation of predicted pressure variation of Poisson’s ratio from the measured data.
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Gomes, Emerson Ferreira. "Astros no rock: uma perspectiva sociocultural no uso da canção na educação em ciências." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/81/81131/tde-28062016-103823/.
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A incorporação de elementos da cultura primeira do estudante no processo de ensino-aprendizagem foi defendida pelo pedagogo francês Georges Snyders (1988) em sua obra \"A Alegria na Escola\". Esta pesquisa contribuiu com essa interface, identificando, no discurso de canções do rock n\' roll, elementos textuais que possibilitem reflexões no âmbito conceitual, epistemológico e sociopolítico sobre a exploração do espaço. O objeto de estudo neste trabalho são canções do período entre as décadas de 1960 e 1970 que possuem representações sobre a astronomia e as missões espaciais. O uso do rock justificou-se pelo fato de temas sobre exploração espacial aparecerem no trabalho de diversos artistas desse gênero musical, permitindo reflexões em nível conceitual, epistemológico e sociopolítico sobre a ciência, a tecnologia e suas relações com a sociedade e o ambiente. Além disso, identificamos que tanto o rock quanto as missões espaciais foram fenômenos culturais que dependeram em sua gênese dos avanços da tecnologia e da ciência e tiveram sua repercussão na sociedade através de processos midiáticos. Essas canções foram selecionadas entre os diversos gêneros de rock, e analisadas a partir de referenciais semiodiscursivos. As atividades foram aplicadas em situações formais de ensino - ensino médio e ensino superior -, em formação continuada de professores e projetos de ensino não formal na escola. No processo de ensinoaprendizagem, foram desenvolvidas atividades que envolviam leitura-comentada da canção, identificando na letra, melodia e harmonia, aspectos que evidenciavam um discurso crítico sobre a ciência e sua relação com a sociedade e o ambiente. Essas atividades envolveram três instâncias: Elaboração, Aplicação e Análise. Como referencial norteador dessas etapas, nos valemos das teorias socioculturais de Vigotski (2001), Snyders (1988) e Freire (2013).The incorporation of elements from the student\'s first culture into the teachinglearning process was supported by the French pedagogue Georges Snyders (1988) in his book \"La joie à l\'ecole\". This research contributed to this interface, by identifying in the discourse of rock \'n\' roll songs textual elements that allow reflections on the conceptual, epistemological and sociopolitical framework of space exploration. The object of study in this work are songs from the 1960s and 1970s, which have representations about astronomy and space missions. The use of rock was justified by the fact that the theme of space exploration is present in the work of several artists of this music genre, allowing reflection on the conceptual, epistemological and sociopolitical level on science, technology and their relationship with society and the environment. In addition, we found that both rock and space missions were cultural phenomena that depended on the advances of technology and science. These songs were selected from the various genres of rock and analyzed taking into account semiotic and discursive references. The activities were applied in formal education settings - high school and higher education - in continuing professional development of teachers and non-formal school projects. In the teaching-learning process, activities were developed involving commented lyrics reading, which aimed at identifying in the lyrics, melody and harmony aspects that evidenced a critical discourse about science and its relationship with society and the environment. These activities encompassed three categories: Development, Implementation and Analysis. These steps were articulated based on the sociocultural theories of Vygotsky (2001), Snyders (1988) and Freire (2013)
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Lueck, Anthony. "Characterizing two carbonate formations for CO₂-EOR and carbon geosequestration: applicability of existing rock physics models and implications for feasibility of a time lapse monitoring program in the Wellington Oil Field, Sumner County, Kansas." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/34629.
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Master of ScienceDepartment of Geology
Abdelmoneam Raef
This study focuses on characterizing subsurface rock formations of the Wellington Field, in Sumner County, Kansas, for both geosequestration of carbon dioxide (CO₂) in the saline Arbuckle formation, and enhanced oil recovery of a depleting Mississippian oil reservoir. Multi-scale data including rock core plug samples, laboratory ultrasonic P-&S-waves, X-ray diffraction, and well log data including sonic and dipole sonic, is integrated in an effort to evaluate existing rock physics models, with the objective of establishing a model that best represents our reservoir and/or saline aquifer rock formations. We estimated compressional and shear wave velocities of rock core plugs for a Mississippian reservoir and Arbuckle saline aquifer, based on first arrival times using a laboratory setup consisting of an Ult 100 Ultrasonic System, a 12-ton hydraulic jack, and a force gauge; the laboratory setup is located in the geophysics lab in Thompson Hall at Kansas State University. The dynamic elastic constants Young’s Modulus, Bulk Modulus, Shear (Rigidity) Modulus and Poisson’s Ratio have been calculated based on the estimated P- and S-wave velocity data. Ultrasonic velocities have been compared to velocities estimated based on sonic and dipole sonic log data from the Wellington 1-32 well. We were unable to create a transformation of compressional wave sonic velocities to shear wave sonic for all wells where compressional wave sonic is available, due to a lack of understandable patterns observed from a relatively limited dataset. Furthermore, saturated elastic moduli and velocities based on sonic and dipole sonic well logs, in addition to dry rock moduli acquired from core plug samples allowed for the testing of various rock physics models. These models predict effects of changing effective (brine + CO₂ +hydrocarbon) fluid composition on seismic properties, and were compared to known values to ensure accuracy, thus revealing implications for feasibility of seismic monitoring in the KGS 1-32 well vicinity.
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Barbery, Albert Marshall. "The effect of water content on the strength of quartzite." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1493211543960308.
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Yuh, Sung H. "Time-lapse seismic monitoring of subsurface fluid flow." [College Station, Tex. : Texas A&M University, 2004. http://hdl.handle.net/1969.1/430.
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Adrian, Jorge Isaac. "Applicability of rock physics models in conjunction with seismic inverted data to characterize a low poro-perm gas-bearing sandstone reservoir for well location optimization, Bredasdorp Basin, SA." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/19963.
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The primary focus of this dissertation is to develop a predictive rock physics theory that establishes relations between rock properties and the observed seismic and to present the results of different seismic characterization techniques to interpret a tight gas sand reservoir off the south coast of South Africa using as input rock physics analysis and inverted seismic outcomes. To perform the aims and goals of this study a workflow that involves the execution of three main processes was implemented: (1) rock physics modelling, (2) a simultaneous seismic inversion, and (3) seismic reservoir characterization techniques. First, a rock physics model was generated as a bridge between the seismic observables (density, Vp and Vs) and reservoir parameters such as fluid content, porosity and mineralogy. In situ and perturbational log - derived forward modelling was performed. Both in situ and perturbational forward modelling were used to generate synthetic seismic gathers, which were used to study the AVA attribute responses. Overall, the effect of fluid fill on this tight gas sand seismically is modest compared with the effect of porosity changes. Second, there follows a detailed description of a workflow implemented to simultaneously invert P and S pre - stack seismic data. The derived elastic properties (acoustic impedance, Vp/Vs and density) were then used in combination with the rock physics analysis to characterize seismically the reservoir. The predicted acoustic impedance and Vp/Vs volumes show a good tie with the log data. However, the density outcome was of limited quality compared with the two mentioned above. Finally, using outcomes from rock physic s analysis and/or inverted data, four seismic techniques to characterize the reservoir were conducted. The techniques involved are: (1) AVO cross - plotting to generate a good facies property based on AVO attributes (intercept - gradient) and rock physics in the area of study , (2) rock physics templates (RPTs) to compute discrete rock property volumes (litho - Sw, litho - porosity) using a collection of curves that cover all possible "what if" lithology - fluid content - porosity scenarios for the reservoir and the inverted data, (3) a lithological classification to calculate litho - facies probability volumes based on a litho - facies classification using petrophysical cut - off s , multivariate probability functions (PDFs) and inverted data, and (4) an extended elastic impedance (EEI) inversion to derive rock property volumes (Vclay, porosity) based on AVO attributes (intercept, gradient). Despite differences in the input and theory behind each technique, all outcomes share parallels in the distribution of good and poor facies or reservoir and non - reservoir zones.
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APOLINÁRIO, Felipe de Oliveira. "Influência da saturação fluida nas propriedades elásticas de rochas carbonáticas." Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/409.
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Capes
O presente trabalho teve como objetivo analisar a influência da saturação fluida nas propriedades elásticas de rochas carbonáticas, bem como a eficácia dos modelos de substituição de fluidos e de simulação computacional. Foram estudadas 9 amostras de rochas carbonáticas, sendo dois calcários laminados e sete tufas. As medições de velocidade foram realizadas em amostras secas, saturadas com água ou com óleo, sob diferentes pressões efetivas. A simulação de propagação de ondas foi feita no COMSOL Multiphysics 5.1, utilizando o Avizo Fire 8.1 para a criação das amostras digitais. Análise por difração de raios X (DRX) foi realizada para determinar a composição das amostras de rocha. Os resultados obtidos nos ensaios laboratoriais e nas simulações computacionais foram comparados com as estimativas dos modelos de substituição de fluidosGassmann, Biot e Brown & Korringa. Foi observado que a saturação das amostras com agua ou óleo geraram aumentos nas velocidades de propagação de onda P, porém sem apresentar um comportamento padrão. Para o caso das ondas S, a saturação por óleo predominantemente gerou aumentos nas velocidades, com exceção para os casos em que as amostras possuíam porosidade secundária do tipo vugular, devido à pouca influência que o óleo oferece para o módulo de cisalhamento nestes casos. A saturação por água resultou em diminuições das velocidades de propagação de onda S devido ao aumento da densidade total. Também foi constatado que o modelo de Gassmann foi o mais efetivo na estimativa de velocidades de onda P e S, enquanto que o de Biot mostrou-se eficaz apenas para a estimativa de velocidades de ondas S, sendo ineficiente para a estimativa de velocidades de ondas P, com erros de até 20%. A simulação computacional gerou resultados superdimensionados, porém que evidenciam que um aperfeiçoamento da metodologia, tal como o aumento do número de pontos de leitura pode gerar resultados mais próximos dos obtidos laboratorialmente e de maior confiabilidade.
This research aimed to analyze the influence of the saturating fluid in carbonate rocks, as well as verify the effectiveness of the fluid substitution models and computational simulations of wave propagation. To do so, nine carbonate rock samples were analyzed, which two of them were laminated limestones and seven were carbonate tufas. The measurement of velocities were made in dry, water saturated and oil saturated samples, under different effective pressures. The wave propagation simulations were made in COMSOL Multiphysics 5.1 using Avizo Fire 8.1 to generate the digital rock samples. The results obtained in lab procedures and in computer simulations were compared with the estimated velocities of the fluid substitution models of Gassmann, Biot and Brown & Korringa. It was observed that the saturation of the samples with water or oil resulted in an increasing of P-wave velocities, however without a pattern. The saturation with oil resulted in most cases in an increasing of S-wave velocities, the exceptions occurred in samples which had vugular porosity, due to the small influence of the oil in the shear modulus in this cases. T he saturation with water resulted in a decreasing of S-wave velocities due to the increment of the bulk density. It was found that the Gassmann’s model was more effective than the other two models in estimating P-wave and S-wave velocities. Biot’s model generated unsatisfying results to P-wave velocities, with errors up to 20%. However, this model had a good accuracy in estimating S-wave velocities. The computer simulations produced mainly overestimated results, though it was shown that an optimization of methodology, such as and addition in the number of the measure points, could improve the quality of the data, providing more representative results.
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Gautre, Christy. "Time-Lapse Depletion Modeling Sensitivity Study: Gas-Filled Gulf of Mexico Reservoir." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1187.
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Time-lapse seismic allows oil/gas reservoir monitoring during production, highlighting compaction and water movement. Time-lapse modeling, using a stress-dependent rock physics model, helps determine the need and frequency of expensive repeat seismic acquisition. We simulate a Gulf of Mexico gas reservoir time-lapse response for depletion and water flooding using uncertainty ranges in water saturation, porosity, stress-induced velocity changes, and pore compressibility. An analysis is conducted to see if a water-swept region could have been predicted. Findings show the swept and un-swept monitor cases amplitude differences range from 6% to 15%, which is higher than the actual monitor seismic noise level. Thus, it is unlikely these cases could be differentiated. However, the modeled amplitude changes from base to monitor cases do not match measured amplitude changes. This suggests the rock property model requires pressure-variance improvement and/or the changes in seismic amplitudes are associated with pressure/porosity, thickness, or saturation cases not modeled.
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Brajanovski, Miroslav. "Effects of fractures on seismic waves in poroelastic formations." Thesis, Curtin University, 2004. http://hdl.handle.net/20.500.11937/2444.
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Naturally fractured reservoirs have attracted an increased interest of exploration and production geophysics in recent years. In many instances, natural fractures control the permeability of the reservoir, and hence the ability to find and characterize fractured areas of the reservoir represents a major challenge for seismic investigations. In fractured and porous reservoirs the fluid affects elastic anisotropy of the rock and also causes significant frequency dependent attenuation and dispersion. In this study we develop a mathematical model for seismic wave attenuation and dispersion in a porous medium in a porous medium with aligned fractured, caused by wave induced fluid flow between pores and fractures. In this work fractures in the porous rock are modelled as very thin and highly porous layers in a porous background. Dry highly porous materials have low elastic moduli; thus dry skeleton of our system contains thin and soft layers, and is described by linear slip theory. The fluid saturated rock with high-porasity layers is described by equations of poroelasticity with periodically varying coefficients. These equations are analyzed using propagator matrix approach commonly used to study effective properties of layered system. This yields a dispersion equation for a periodically layered saturated porous medium taking into account fluid communication between pore spaces of the layers. Taking in this dispersion equation a limit of small thickness for high-porosity layers gives the velocity and attenuation as a function of frequency and fracture parameters. The results of this analysis show that porous saturated rock with aligned fractures exhibits significant attenuation and velocity dispersion due to wave induced fluid flow between pores and fractures.At low frequencies the material properties are equal to those obtained by anisotropic Gassmann theory applied to a porous material with linear-slip, interfaces. At high frequencies the results are equivalent to those for fractures with vanishingly small normal slip in a solid (non-porous) background. The characteristic frequency of the attenuation and dispersion depends on the background permeability, fluid viscosity, as well as fracture density and spacing. The wave induced fluid flow between pores and fractures considered in this work has exactly the same physical nature as so-called squirt flow, which is widely believed to by a major cause of seismic attenuation. Hence, the present model can be viewed as a new model of squirt-flow attenuation, consistent with Biot’s theory of poroelasticity. The theoretical results of this work are also limited by the assumption of periodic distribution of fractures. In reality fractures may be distributed in a random fashion. Sensitivity of our results to the violation of the periodicity assumption was examined numerically using reflectivity modelling for layered poroelastic media. Numerical experiments for a random distribution of fractures of the same thickness still show surprisingly good agreement with theoretical results obtained for periodic fractures. However this agreement may break down if fracture properties are allowed to vary from fracture to fracture. The results of this thesis show how to compute frequency dependences of attenuation and velocity caused by wave induced fluid flow between pores and fractures. These results can be used to obtain important parameters of fractured reservoirs, such as permeability and fracture weakness, from attenuation measurements. The major requirement for the success of such an approach is that measurements must be made in over a relatively broad frequency range.
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Poppeliers, Christian. "Wear Due to the Physical and Petrographic Properties of Rocks and their Dynamic Interactions with Mining Equipment." PDXScholar, 1996. https://pdxscholar.library.pdx.edu/open_access_etds/5149.
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Wear to mining equipment reduces operational efficiency. If wear rates can be predicted, appropriate matching of alloys to the mine' s geologic conditions can aid in improving the operational efficiency. This study addresses rock characteristics which lead to wear. Macroscopic rock tools which lead to wear include sharp edges and comers on rocks. During a rock/equipment interaction, these rock tools cause high point pressures on the surface of the equipment which leads to ductile cutting and gouging of the surface and subsequent removal of metal. Hard mineral grains, or grain tools, produce abrasion as the grains move across equipment surfaces. Grain and rock tools were analyzed for metamorphic, hydrothermally altered, plutonic, and sedimentary rocks from six mines and quarries. Grain tools were examined by petrographic analysis and Knoop microhardness: rock tools by uniaxial compressive tests, density, and rock size. Fourier analysis of rock and mineral shapes and abrasion tests were used to examine the evolution of tools. Prediction of wear rates appears most closely related to uniaxial compressive strength, Knoop microhardness, and quartz content. Uniaxial compressive strength relates to rock tool endurance; Knoop microhardness contrast between mineral grains and matrix/cement influences evolution of tools during surface interactions; quartz content relates to the abrasive capacity of a rock surface.
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Elliott, Christine Eleanor. "Physical Rock Weathering Along the Victoria Land Coast, Antarctica." Thesis, University of Canterbury. Geography, 2006. http://hdl.handle.net/10092/1305.
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The purpose of this research was to investigate the physical weathering of rock along the Victoria Land Coast, Antarctica. It was designed to contribute to the Latitudinal Gradient Project, a joint initiative between the New Zealand, Italian and United States Antarctic Programmes. The Latitudinal Gradient Project aims to improve our understanding of the ecosystems of the Dry Valleys and ice-free areas of the Ross Sea Region and, by using latitude as a proxy measure, identify how they might be affected by future climate change. The approach taken for this research was to use information on rock (from one rock group) temperature and moisture conditions gathered from three field locations to inform laboratory simulations. The laboratory simulations would then be used to investigate the weathering of small rock blocks and aggregates. Two temperature cycles approximating those experienced during summer and spring/autumn were identified and simulations undertaken in a specially adapted freezer. Three levels of moisture were applied: no moisture, half saturation and full saturation. Results of the laboratory simulations indicated that although rocks responded in different ways to different processes, granular disintegration took place even in the absence of additional moisture and did not require crossings of the 0 OC isotherm, nor were high levels of moisture required for across zero temperature cycling to produce weathering effects. A model that related weathering to latitude was developed and changes in climate explored. It was found that the weathering effect of summer and spring/autumn cycles was different and depended on rock characteristics rather than latitude. Increasing the ratio of summer to spring/autumn temperature cycles by 10% indicated that weathering could decrease or remain the same depending on the particular rock. Changes in temperature were found to be more important than changes in moisture. A weathering index that related local climate and rock properties to weathering was also developed and this highlighted the difficulties of using laboratory results to predict field rates of weathering. There were some surprising results from the field, including the presence of much more moisture on the surface of the rock, primarily from blowing snow, than had been predicted for this dry environment. This occurred even in the presence of negative rock surface temperatures. In addition, winter rock surface temperatures can fluctuate up to 25 OC, getting as warm as -10 OC. Macro-climate and changes in air temperature in response to foehn and katabatic winds were the drivers for these fluctuations.
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Brajanovski, Miroslav. "Effects of fractures on seismic waves in poroelastic formations." Curtin University of Technology, Department of Exploration Geophysics, 2004. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=15309.
Full textAbstract:
Naturally fractured reservoirs have attracted an increased interest of exploration and production geophysics in recent years. In many instances, natural fractures control the permeability of the reservoir, and hence the ability to find and characterize fractured areas of the reservoir represents a major challenge for seismic investigations. In fractured and porous reservoirs the fluid affects elastic anisotropy of the rock and also causes significant frequency dependent attenuation and dispersion. In this study we develop a mathematical model for seismic wave attenuation and dispersion in a porous medium in a porous medium with aligned fractured, caused by wave induced fluid flow between pores and fractures. In this work fractures in the porous rock are modelled as very thin and highly porous layers in a porous background. Dry highly porous materials have low elastic moduli; thus dry skeleton of our system contains thin and soft layers, and is described by linear slip theory. The fluid saturated rock with high-porasity layers is described by equations of poroelasticity with periodically varying coefficients. These equations are analyzed using propagator matrix approach commonly used to study effective properties of layered system. This yields a dispersion equation for a periodically layered saturated porous medium taking into account fluid communication between pore spaces of the layers. Taking in this dispersion equation a limit of small thickness for high-porosity layers gives the velocity and attenuation as a function of frequency and fracture parameters. The results of this analysis show that porous saturated rock with aligned fractures exhibits significant attenuation and velocity dispersion due to wave induced fluid flow between pores and fractures.At low frequencies the material properties are equal to those obtained by anisotropic Gassmann theory applied to a porous material with linear-slip, interfaces. At high frequencies the results are equivalent to those for fractures with vanishingly small normal slip in a solid (non-porous) background. The characteristic frequency of the attenuation and dispersion depends on the background permeability, fluid viscosity, as well as fracture density and spacing. The wave induced fluid flow between pores and fractures considered in this work has exactly the same physical nature as so-called squirt flow, which is widely believed to by a major cause of seismic attenuation. Hence, the present model can be viewed as a new model of squirt-flow attenuation, consistent with Biot’s theory of poroelasticity. The theoretical results of this work are also limited by the assumption of periodic distribution of fractures. In reality fractures may be distributed in a random fashion. Sensitivity of our results to the violation of the periodicity assumption was examined numerically using reflectivity modelling for layered poroelastic media. Numerical experiments for a random distribution of fractures of the same thickness still show surprisingly good agreement with theoretical results obtained for periodic fractures. However this agreement may break down if fracture properties are allowed to vary from fracture to fracture. The results of this thesis show how to compute frequency dependences of attenuation and velocity caused by wave induced fluid flow between pores and fractures. These results can be used to obtain important parameters of fractured reservoirs, such as permeability and fracture weakness, from attenuation measurements. The major requirement for the success of such an approach is that measurements must be made in over a relatively broad frequency range.
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Canessi, Tomà. "Physical modelling of rock fragmentation upon impact." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Rockfall represents a significant safety hazard in building, civil and mining environment that can cause serious injuries and fatalities and can damage structures, infrastructure and machinery. It is extremely costly to manage and public authorities need reliable tools to study and design protection structures as the performance of the existing structures are variable. Many studies and experiments have been done, but one aspect would lead to a better comprehension of the subject: the fragmentation of blocks upon impact. Rocks commonly break up upon impact but rockfall prediction models currently available mostly ignore this phenomenon, even though fragmentation changes size, shape and energy of falling blocks and can drastically change the outcome of the design of protective structure. For example, if a large rock breaks upon impact and its mass and energy are divided among fragments, a high level of energy is dissipated and ignoring fragmentation would lead on an overdesign of the protection barrier. Moreover, very fast rock fragments may rupture a rockfall protection. The project aims to overcome this limit, studying and considering fragmentation in rockfall model, allowing assessment of the hazard rising from a shattered rock. The intention is to develop a database of experimental data about fragmentation of blocks upon impact by considering the initial conditions that cause fragmentation, the fragment size and mass distribution, the partition of velocity and energy at impact and what may lead to “bullet effect” or high flying fragment. This project aims to include fragmentation in rockfall prediction causes to facilitate a better and safer mitigation of rockfall hazard. Moreover, a better knowledge will directly translate into economical and societal benefits, such as more cost effective and better user experience.
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Beesley, M. L. G. "An investigation of wellbore stability using numerical and physical modelling." Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254203.
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Barbouteau, Sandra. "Suivi de substitution de fluides dans les roches par corrélation de bruit : Expériences ultrasonores au laboratoire et surveillance continue en cours d’exploitation du sous-sol." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENU045/document.
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L'interférométrie sismique, tout comme l'interférométrie optique, étudie les phénomènes d'interférence entre des couples de signaux sismiques afin de mettre en évidence des différences entre ces signaux (par exemple Curtis et al. 2006). Les traitements utilisés consistent le plus souvent à corréler les enregistrements entre différents capteurs pour remonter aux fonctions de Green, (ou réponse impulsionnelle) entre ces récepteurs (par exemple, Derode et al. (2003), Wapenaar et al. (2004), Larose et al. (2006), Sanchez-Sesma et Campillo (2006)). Ce principe a déjà été appliqué avec succès dans les domaines de la sismologie (Campillo et Paul (2003)), des ultrasons (Weaver et Lobkis (2001)), de l'exploration sismique (Schuster (2001) et Wapenaar et al. (2004)), et même de l'hélio-sismologie (Duvall et al. (1993)) Dans tous ces cas, l'analyse des corrélations a conduit à une description détaillée des milieux de propagation, en l'occurrence l'intérieur de la Terre dans le cas de la sismologie. La sismique passive, par opposition à la sismique active utilisant les sources cohérentes artificielles (explosifs, canons à air, vibrateurs...), exploite les sources cohérentes naturelles (séismes...). Depuis peu la sismique passive exploite également des champs d'ondes aléatoires engendrées à des temps inconnus par une multitude de sources inconnues dans le sous-sol qui sont enregistrées à différentes positions de récepteurs. L'analyse par interférométrie sismique des enregistrements à deux capteurs permet de remonter aux fonctions de Green, ou réponse impulsionnelle, entre ces deux récepteurs (Derode et al. (2003)). Cette thèse, à vocations à la fois expérimentale et applicative, a deux buts : - vérifier au laboratoire, sur des expériences ultrasonores et avec différents types de roches, l'efficacité du monitoring de substitution de fluides par l'analyse interférométrique ultrasonore - appliquer sur le terrain les méthodes d'interférométrie sismique passive à des expériences ponctuelles de surveillance sismique passive d'exploitation du sous-sol. Ce manuscrit présente, après une synthèse bibliographique, la mise au point d'une nouvelle méthode de mesure des constantes élastiques d'un échantillon de roche (sèche ou saturée de fluide) basée sur les principes de l'interférométrie ultrasonore et de la spectroscopie par résonance ultrasonore. La méthode a été testée et validée (reproductibilité, fidélité, fiabilité…) sur un matériau standard de propriétés connues (aluminium). On expose que les effets de substitution fluide sont tout-à-fait mesurables avec la méthode sur divers échantillons de roches sèches puis saturées (en eau ou en éthylène glycol) et les résultats sont en accord raisonnable avec la théorie poroélastique de Biot-Gassmann. En outre, un certain nombre de faiblesses de la méthode ont été mises en évidence, à savoir la limitation à des roches assez homogènes et peu atténuantes. La dernière partie de ce manuscrit met en évidence des variations de vitesse des ondes dans un champ d'hydrocarbures (informations relatives à ce champ confidentielles) concomitantes avec le début de l'injection de vapeur dans celui-ci (pour récupération assistée de l'huile)Seismic interferometry, like optic interferometry, studies the interferences phenomena between couples of seismic signals, with the aim of pointing at differences between those signals (Curtis et al. 2006 for instance). The data processing consists, generally, in correlating the recordings between different stations to retrieve the Green's function between these sensors (Derode et al. (2003), Wapenaar et al. (2004), Larose et al. (2006), Sanchez-Sesma et Campillo (2006)). This principle has already been successfully applied in the field of seismology (Campillo and Paul (2003)), ultrasound (Weaver et Lobkis (2001)), seismic exploration and even helioseismology (Duvall et al. (1993)). In all these cases, the analysis of the correlations leads to a detailed description of the propagation medium. Contrary to active seismic which uses artificial coherent sources (explosives, air guns…), passive seismic exploits natural coherent sources (seisms…). Since a few years, passive seismics also exploits random wave fields generated at unknown times by many unknown sources in the ground, and recorded at different stations positions. The analysis with cross-correlation of pairs of recordings, from pairs of sensors, leads to the Green's function between the two sensors (Derode et al. (2003)). This thesis has two objectives: -to check, at the lab scale, the effectiveness of monitoring of fluids substitution with noise correlation (ultrasound scale) in rocks -to apply noise correlation methods to passive seismic monitoring of a hydrocarbons field. This thesis presents, after a state of the art, the set-up of a new method to measure elastic constants of a rock sample (dry or fluid-saturated), based on ultrasound interferometry principle and resonant ultrasound spectroscopy. The method has been tested and validated (reproducibility, accuracy, precision…) on a standard material (aluminium). We show that the effects of a fluids substitution are measurable on various rock samples (dry or saturated, with water or with ethylene glycol) with this method. Plus the results are in agreement with Biot-Gassmann's theory. Besides, several weaknesses of the method were pointed, that is to say the method does not work on heterogeneous or attenuating medium. The last part of this thesis exposes speed of waves variations in a hydrocarbons field, when steam is injected simultaneously inside the reservoir (enhanced oil recovery operation)
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Al-Awad, Musaed Naser J. "Physico-chemical analysis of shale-drilling fluid interaction and its application in borehole stability studies." Thesis, Heriot-Watt University, 1994. http://hdl.handle.net/10399/1368.
Full textAbstract:
Shale is often the most difficult of all formations to maintain a stable wellbore in when drillincr ::> for oil and gas. Time and money spent overcoming this problem during drilling, together with overall reduced profit margins. has led the oil industry to devote considerable time and effort to solve the problem of unstable boreholes in shales. It has long been established that the moisture adsorption (or desorption) of shale rocks can be controlled by the salinity of drilling fluid. When compacted shale (under constant compaction stress) adsorbs moisture, its total volume increases and swelling strains develop. Developed swelling strains then become an integral part of the effective radial stress acting on the shale formation contributing to borehole failure. A mathematical model has been developed for predicting the swelling behaviour of shale when placed in contact with water under moderate pressures and the effect of the swelling on borehole (in)stability. The model is based on thermodynamic theory which suggests that fluid movement into or out of a shale is driven by an imbalance in the partial molar free energy of the shale and the contacting fluid. Conversion of the free energy of each system (fluid and shale) into "total swelling pressure" made it possible to model transient pressures and strains generated in shale. The analytical solution of the radial diffusivity equation is reduced to a simpler form for the model. The model was validated using equipment and experimental techniques which allow continuous monitoring of shale swelling as function of time and distance from the wetting end. It was found that increasing the compaction stress acting on the shale reduced the rate of swelling, and increasing the hydraulic pressure of the fluid on the shale's wetted surface increased the rate of swelling. This behaviour was adequately described by the model which therefore represents a new method for predicting shale swelling as function of time and radial distance under different environments. Swelling strains are then used to predict related changes in shale mechanical properties (failure criteria) and well (in)stability. Several well-site index tests have been developed to study shale-drilling fluid interaction at wellsite. These index tests can provide input data for the mathematical model. Drilling fluids can be screened for their ability to control shale swelling, thus minimising the risk of well bore instability.
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Wu, K. O. "The modelling of anisotropic jointed rock slopes by physical and numerical methods." Thesis, University of the West of Scotland, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234764.
Full textAbstract:
In this study the stabili ty and stress distribution of anisotropic jointed rock slopes under external loading were examined. The influence of joint orientation and mechanical characteristics on the engineering behaviour of jointed rock slopes were included in the investigation. A total of four physical models were developed by using blocks of light-weight concrete and gypsum mortar to simulate intact rocks and joints respectively. The models were built within a confining frame such that plane strain conditions were maintained throughout the experiments. The stress-strain relationship and the strength of the model blocks were determined from laboratory tests. An empirical equation was established to represent the strength envelope of the model material and rocks in general. The normal and shear properties of the model rock JOints were examined, and were described by mathematical expressions in order to facilitate the numerical studies. Results from the physical modelling studies showed that localised failure regions were induced and three types of failure modes were identified. The stability and stress distribution wi thin the models were found to be significantly influenced by the properties and system of the jointing. Two computer programs were developed based on the Finite Element Method and Coupled Finite-Boundary Element Method in order to simulate the behaviour of jointed rock masses and assessments of their application were made in comparison with the physical modelling results. A special finite joint element was developed to incorporate the non-linearity and anisotropy behaviour of rock joints. The finite element program was successfully executed and gave reasonable results in which the principal stress distributions were generally in agreement with those obtained from the physical models. The finite-boundary element program on the other hand introduced boundary incompatibility in the system and therefore led to divergency.