Tesi: "Reservoirs – Mathematical models"

1

Yeates, Peter Stafford. "Deep mixing in stratified lakes and reservoirs". University of Western Australia. Centre for Water Research, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0046.

Testo completo

Abstract (sommario):

The onset of summer stratification in temperate lakes and reservoirs forces a decoupling of the hypolimnion from the epilimnion that is sustained by strong density gradients in the metalimnion. These strong gradients act as a barrier to the vertical transport of mass and scalars leading to bottom anoxia and subsequent nutrient release from the sediments. The stratification is intermittently overcome by turbulent mixing events that redistribute mass, heat, dissolved parameters and particulates in the vertical. The redistribution of ecological parameters then exerts some control over the ecological response of the lake. This dissertation is focused on the physics of deep vertical mixing that occurs beneath the well-mixed surface layer in stratified lakes and reservoirs. The overall aim is to improve the ability of numerical models to reproduce deep vertical mixing, thus providing better tools for water quality prediction and management. In the first part of this research the framework of a one-dimensional mixed-layer hydrodynamic model was used to construct a pseudo two-dimensional model that computes vertical fluxes generated by deep mixing processes. The parameterisations developed for the model were based on the relationship found between lake-wide vertical buoyancy flux and the first-order internal wave response of the lake to surface wind forcing. The ability of the model to reproduce the observed thermal structure in a range of lakes and reservoirs was greatly improved by incorporating an explicit turbulent benthic boundary layer routine. Although laterally-integrated models reproduce the net effect of turbulent mixing in a vertical sense, they fail to resolve the transient distribution of turbulent mixing events triggered by local flow properties defined at far smaller scales. Importantly, the distribution of events may promote tertiary motions and ecological niches. In the second part of the study a large body of microstructure data collected in Lake Kinneret, Israel, was used to show that the nature of turbulent mixing events varied considerably between the epilimnion, metalimnion, hypolimnion and benthic boundary layer, yet the turbulent scales of the events and the buoyancy flux they produced collapsed into functions of the local gradient Richardson number. It was found that the most intense events in the metalimnion were triggered by high-frequency waves generated near the surface that grew and imparted a strain on the metalimnion density field, which led to secondary instabilities with low gradient Richardson numbers. The microstructure observations suggest that the local gradient Richardson number could be used to parameterise vertical mixing in coarse-grid numerical models of lakes and reservoirs. However, any effort to incorporate such parameterisations becomes meaningless without measures to reduce numerical diffusion, which often dominates over parameterised physical mixing. As a third part of the research, an explicit filtering tool was developed to negate numerical diffusion in a threedimensional hydrodynamic model. The adaptive filter ensured that temperature gradients in the metalimnion remained within bounds of the measured values and so the computation preserved the spectrum of internal wave motions that trigger diapycnal mixing events in the deeper reaches of a lake. The results showed that the ratio of physical to numerical diffusion is dictated by the character of the dominant internal wave motions.

Gli stili APA, Harvard, Vancouver, ISO e altri

2

Estalrich-Lopez, Juan. "Short-term operation of surface reservoirs within long-term goals". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184854.

Testo completo

Abstract (sommario):

A stochastic dynamic programming model (called P.B.S.D.P.) based on the consideration of peak discharge and time between peaks as two stochastic variables has been used to model and to solve a reservoir operation problem. This conceptualization of the physical reality allows to solve, in this order, the tactical and strategic operation of surface reservoirs. This P.B.S.D.P. model has been applied to the Sau reservoir in the Northeastern corner of Spain. The results showed a significant improvement over the currently used operation procedure, yielding values of yearly average electricity production that are somewhat under 6% of what could have been the maximum electricity production.

Gli stili APA, Harvard, Vancouver, ISO e altri

3

Ugbo, Justin Petroleum Engineering Faculty of Engineering UNSW. "A new model for evaluating water saturation in shaly sand reservoirs using quantitative x-ray diffraction and cation exchange capacity cliff head field, Western Australia". Awarded by:University of New South Wales. Petroleum Engineering, 2007. http://handle.unsw.edu.au/1959.4/40443.

Testo completo

Abstract (sommario):

Interpretation problems are commonly associated with calculating water saturation in nonhomogenous shaly sand reservoirs. Redefining petrophysical properties based on well logs in shaly sand reservoirs by using fundamental geologic attributes is an important tool in developing subsurface hydrocarbon resources. Studies of the electrical anisotropy of shaly sands have shown that the level of our understanding and our ability to correctly evaluate low resistivity and low contrast pay can be greatly improved. The model developed in this thesis is similar in form to the shaly sand Dual Water model by Clavier et al. (1984). It is an experiment based model designed to directly assess and quantify the mineralogical and electrical effects of clay minerals in heterogeneous reservoirs. Clay minerals usually have multiple effects on petrophysical properties obtained from geophysical well log measurements. The total expansible clay model evaluates these effects via direct measurement of independent mineralogy and conductivity of clay minerals within reservoir sands. This model integrates the following as an effective basis for characterizing shaly sand reservoirs: ??? Rietveld based Siroquant assay for quantitative X-ray diffraction, used in determining mineral percentages from standard XRD trace patterns, ??? Cation exchange capacity, used to determine the quantity of cations involved in the exchange at the shale-water interface, ??? Porosity, permeability, density and resistivity measurements, ??? Thin section petrography, used in identifying mineral patterns, visible porosity and reservoir quality. Overall, application of correlations drawn from the model yields improved results for water saturation which appeared consistent with those earlier calculated using known water saturation models (Clavier et al Dual Water model, 1984, Juhasz, 1981). A total of twenty three samples from two wells in the Cliff Head fIeld were analyzed for this study.

Gli stili APA, Harvard, Vancouver, ISO e altri

4

García, Iturbe Selma L. "Simulation of physical and chemical processes in reservoirs: Two case studies". Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4968/.

Testo completo

Abstract (sommario):

Managing water quality aspects requires the use of integrative tools that allow a holistic approach to this problem. Water quality models coupled to hydrodynamic models are these tools. This study presents the application of the water quality model WASP coupled to the hydrodynamic model DYNHYD for two distinct reservoirs: Lake Texoma and Tocoma Reservoir. Modeling the former included simulations of water velocities, water level, and four chemical and physical compounds: chlorides, dissolved oxygen (DO), biochemical oxygen demand (BOD), and total suspended solids (TSS); and validation of the results by comparing with observed values during March - May, 1997. The latter is still under project status and the simulation was performed in a prospective way. The analysis included simulations of water velocities under current and for expected conditions, DO and BOD. Both models, DYNHYD and WASP, fitted pretty well to observed conditions for Lake Texoma and for where Tocoma Reservoir has been planned. Considering management and decision support purposes, the role of boundary and loading conditions also was tested. For Lake Texoma, controlling boundary conditions for chlorides is a determinant factor for water quality of the system. However, DO and TSS in the reservoir are governed by additional process besides the condition of the boundary. Estimated loadings for this system did not provided significant effects, even though the allocation of a load for chlorides resulted in significant changes in the trend for expected chloride concentrations at the Washita River Arm of Lake Texoma. For Tocoma Reservoir, the expected concentration of DO all over the reservoir is going to driven by boundary conditions, as well as by the management of autochthonous BOD loadings provided by vegetation decomposition. These two factors will be determinant for the resulting water quality of the future reservoir.

Gli stili APA, Harvard, Vancouver, ISO e altri

5

Amorim, Elisa Portes dos Santos. "Ajuste automático de histórico em reservatórios de petróleo utilizando o método TSVD". Universidade Federal de Juiz de Fora (UFJF), 2009. https://repositorio.ufjf.br/jspui/handle/ufjf/4107.

Testo completo

Abstract (sommario):

Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-04-20T12:43:51Z No. of bitstreams: 1 elisaportesdossantosamorim.pdf: 22640735 bytes, checksum: 208231549a369d305ed644548f61de21 (MD5)
Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-20T13:11:28Z (GMT) No. of bitstreams: 1 elisaportesdossantosamorim.pdf: 22640735 bytes, checksum: 208231549a369d305ed644548f61de21 (MD5)
Made available in DSpace on 2017-04-20T13:11:28Z (GMT). No. of bitstreams: 1 elisaportesdossantosamorim.pdf: 22640735 bytes, checksum: 208231549a369d305ed644548f61de21 (MD5) Previous issue date: 2009-11-09
A simulação de reservatórios é uma ferramenta amplamente utilizada por engenheiros de reservatório. É principalmente utilizada com o objetivo de prever o comportamento de reservatórios sob diferentes condições, auxiliando os engenheiros a tomarem importantes decisões que podem envolver custos financeiros elevados. A fim de obter predições confiáveis, diferentes propriedades petrofísicas do reservatório, como a porosidade e a permeabilidade, devem ser conhecidas. Porém, medições diretas dessas propriedades são possíveis apenas nas proximidades dos poços. Uma forma de estimar essas propriedades é através do processo de ajuste de histórico. O processo de ajuste de histórico consiste no problema inverso de estimar as propriedades de um reservatório através do ajuste de dados simulados ao histórico do reservatório, o qual está disponível em reservatórios em operação já há algum tempo. Neste trabalho apresentamos um estudo para o ajuste de histórico automático baseado em um modelo de reservatório bifásico (óleo/água) e bidimensional. A taxa de produção de óleo e a pressão, medidas nos poços são tomadas como histórico do reservatório. Desejamos estimar a distribuição de permeabilidades do reservatório. O problema de ajuste de histórico consiste em minimizar uma função objetivo que quantifica o erro entre o histórico e os dados simulados, o que leva a um problema de mínimos quadrados não-linear. Para resolver este problema, utilizamos o método de Gauss-Newton combinado com o método de Decomposição em Valores Singulares Truncada (TSVD). O método TSVD reduz consideravelmente o número de parâmetros a serem estimados, reduzindo também o custo computacional envolvido na resolução do problema. A m de utilizarmos o método TSVD eficientemente é necessário dispor da derivada e adjunta do problema direto. O desenvolvimento dessas ferramentas consistiu de parte importante no desenvolvimento deste trabalho.
Reservoir simulation is an essential tool extensively used by reservoir engineers. It is mostly employed to predict reservoir behavior under different circumstances, thus supporting decisions that frequently involve large fnancial costs. In order to use this tool properly different petro-physical properties of the reservoir must be well known, such as permeability and porosity. Unfortunately, direct measures of these properties are viable only near the wells. A way of estimating these properties is through the so called History Matching process. History matching process consists on the inverse problem of estimating reservoir properties through matching simulated data to reservoir history, which are available in reservoirs that are operating for some time. In this work we present a study for the automatic history matching based in a two-phase (oil/water), two dimensional reservoir model. The rate of oil production and the pressure measured at the wells are taken as the history of the reservoir. In this work, we aim to estimate the permeability distribution of the reservoir. The history matching problem consists on minimizing an objective function that measures the mismatch between reservoir history and simulated data, which turns the problem into a nonlinear least square problem. In order to solve this problem the Gauss-Newton method was employed combined with the Truncated Singular Value Decomposition (TSVD) technique. The TSVD technique reduces considerably the number of parameters to estimate, reducing also the computational effort involved in solving the problem. In order to use the TSVD method in an effcient way it is necessary to have the derivative and the adjoint of the direct problem. The development of these tools was an important part of this work.

Gli stili APA, Harvard, Vancouver, ISO e altri

6

Castro, Marcelo Mendes de. "Modelação matemática de lagos e reservatórios: caso do Reservatório Billings". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3147/tde-18082010-165433/.

Testo completo

Abstract (sommario):

Modelos numéricos são importantes ferramentas para avaliação do comportamento de corpos hídricos, notadamente com relação ao decaimento e mistura de constituintes ao longo do tempo. Neste trabalho apresenta-se o método empregado para adaptação e aplicação de um modelo matemático hidrodinâmico 2DH para simulação de variáveis de qualidade das águas a reservatórios rasos ou polimíticos. A descrição do desenvolvimento do modelo empregado (IPH-ECO), do processo de análise das condições do reservatório, seleção de dado intervenientes, discretização espacial e temporal, definição das condições de contorno hidrológicas e de aporto de cargas poluentes, bem como a definição espacial dos pontos de controle para aferição e validação são discutidos. São apresentados os resultados da resposta do modelo aplicado ao Reservatório Billings, em São Paulo.
Numerical models are strong tools to evaluate the fate of pollutants in lakes and reservoirs under transient conditions. This article brings the steps employed for preparation and implementation of a hydrodynamic 2DH model to simulate water quality variables in shallow or polymitc lakes. Description of the adaptation and implementation of IPH-ECO model process, compiling and setting of the hydrological and constituent loadings, spatial and temporal discretization and selection of control points are demonstrated and discussed. Some results of model calibration for Billings Reservoir, Sao Paulo, Brazil, are also presented.

Gli stili APA, Harvard, Vancouver, ISO e altri

7

Sancevero, Sergio Sacani. "Estudo de aplicação de metodos quantitativos em dados sismicos no processo de caracterização integrada de reservatorios". [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287444.

Testo completo

Abstract (sommario):

Orientador: Armando Zaupa Remacre
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociencias
Made available in DSpace on 2018-08-09T03:37:21Z (GMT). No. of bitstreams: 1 Sancevero_SergioSacani_D.pdf: 13993022 bytes, checksum: beb2507aee5ca130897dad57c706b2a9 (MD5) Previous issue date: 2007
Resumo: O processo de caracterização de reservatórios é atualmente uma das etapas mais importantes na exploração, desenvolvimento e produção de um campo. Porém, para que esse processo seja realizado da melhor forma possível é preciso se ter o conhecimento de determinados métodos, que integram as diferentes informações disponíveis. Desse modo, o objetivo principal dessa tese é estudar de forma criteriosa e quantitativa o processo de caracterização de reservatórios do ponto de vista dos dados sísmicos, avaliando antigos e novos métodos, e definindo novas metodologias que possam ser aplicadas de maneira decisiva neste processo. Para que esses métodos pudessem ser avaliados de maneira conclusiva foi utilizado nesta tese um modelo sintético que reproduzisse minimamente algumas características cruciais de determinados reservatórios como a complexa distribuição dos corpos de areia e a presença de corpos com espessura subsísmica que levassem ao limite as técnicas de modelagem tradicionais, proporcionando avaliar novos métodos. Assim, para caracterizar essas complexas feições, foram utilizados nesta tese dois meios principais de interpretação, primeiro a inversão sísmica dando um caráter preditivo ao dado sísmico e por fim a análise multiatributos, dando um caráter classificatório. No caso da inversão sísmica foram utilizados três métodos de obtenção da impedância acústica. Entre eles, foi a inversão geoestatística que demonstrou ser a mais eficiente das técnicas no que diz respeito à caracterização de reservatórios com espessura subsísmica e complexa distribuição dos corpos de areia. No caso dos atributos, pôde-se demonstrar que é necessário que sejam tratados com uma abordagem multivariada para que seja aproveitada a correlação entre eles e que por meio de técnicas de classificação e modelagem possa se decidir os mais relevantes para o processo. Neste caso 3 métodos de análise multivariada foram apresentados e testados, sendo que dois deles (ICA e MAF) de maneira inédita e que produziram resultados superiores àqueles alcançados quando a tradicional técnica de PCA é aplicada. Assim, com o que foi apresentado, pode-se concluir que o processo de caracterização é um estágio crucial para o desenvolvimento dos campos, mas não é fácil de ser realizado, a menos que os métodos e as técnicas envolvidas sejam conhecidas de maneira profunda. Só assim, é possível extrair o máximo de informações do dado sísmico, caracterizando o reservatório de forma quantitativa e integrada, otimizando sua produção e reduzindo os riscos e custos com a sua explotação
Abstract: The reservoir characterization process can be considered curretly the most important stage in the exploration, development and production of the oil field. However, this process is only carried out in the best way if the geologists, geophisicist and engineering has the knowledge of some definitive methods and techniques that integrated all information available about the field. Thus, the aim of this thesis is to study in a criterious and quantitative way the reservoirscharacterization process, analyzing the seismic data,by the evaluation of classic and novel methods, to defining new methodlogies that can be applied in decisive way into this process. So, for these methods could be evaluated in a conclusive way, were used in this thesis asynthetic reference model that reproduced some critical features of determined reservoirs, as the complex distribution of sand bodies and the subseismic thickness. These characteristics pushing to the limit the traditional modelling techniques. In this thesis to characterizze the complex features present in the reference model we used two interpretation techniques, first we analyze the seismic inversion that give a preditive character to the seismic data and after we study the multiattribute analysis that give a classificatory caracter to the seismic interpretation. For the seismic inversion, the stochastic or geostatistical inversion, that demonstrated to be the most efficient technique to characterized the complex and the subseismic features present in the model. About the seismic attributes it could be demonstrated that even so in some cases they represent the features of the model, are necessary that they are dealt with a multivariate approach, to used the advantage of the correlation between them. For the seismic attribute analysis, 3 methods of multivariate statistics analysis were used, two of them (ICA and MAF) for the first time in the reservoir characterization processo With the results we can proved that these 2 new methods improved the process of multiattribute anlysis prducing superior results when compare with the results obtained by the application of traditional PCA technique. With it was presented, can be concluded that the reservoir characterization process is a crucial stage and have some difficults to be accomplishment, unless the methods and the involved techniques are known deeply. Thus it is possible to extract the maximum informations from the datasets, characterizing the reservoir in a quantitative and integrated environmental, optimizing its production and reducing the risks and the costs with its explotation
Doutorado
Administração e Politica de Recursos Minerais
Doutor em Ciências

Gli stili APA, Harvard, Vancouver, ISO e altri

8

Costa, Samuel Barsanelli. "Modelo unidimensional preliminar de transporte de sedimentos para o reservatório Taiaçupeba". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3147/tde-03052018-091135/.

Testo completo

Abstract (sommario):

A modelagem unidimensional tem sido adotada desde os anos 1980, com sucesso nas práticas de engenharia, para a caracterização do regime de transporte de sedimentos de longo termo. É também uma importante ferramenta para o entendimento da dinâmica sedimentar de bacias e gestão de sedimentos em reservatórios. Esta pesquisa teve como objetivo aplicar a modelagem unidimensional de transporte de sedimentos na bacia do reservatório Taiaçupeba, São Paulo, Brasil, a partir do sistema computacional HEC-RAS, orientada à estimativa das descargas sólidas afluentes ao reservatório. O período de coleta de dados coincidiu com a estiagem de 2013-2015 na Região Sudeste, o que contribuiu com a análise crítica do método e dos resultados, cuja discussão ressalta o uso da modelagem unidimensional como instrumento eficaz de validação das curvas de sedimento para caracterização do regime de transporte. As funções de capacidade de transporte de Laursen-Copeland e Toffaleti mostraram-se aplicáveis a esse sistema fluvial, bem como os métodos de encouraçamento de fundo de Hirano e Thomas-Copeland. Os coeficientes de Manning ajustados foram considerados preliminares e dados de campo adicionais são encorajados para refinar seu ajuste e incorporar maior acurácia na estimativa do perfil da linha d\'água em trabalhos futuros. Além disso, são apresentadas recomendações metodológicas ao monitoramento fluvissedimentométrico que contribuem com a sistematização das técnicas e tecnologias disponíveis à pesquisa hidrossedimentológica.
One-dimensional modeling has been successfully adopted since the 1980s in engineering practices to assess long-term sediment transport regimes. It is also an important tool for the understanding of sediment dynamics in watersheds and sediment management in reservoirs. The objective of this research was to apply the one-dimensional sediment transport modeling in the Taiacupeba reservoir basin, located in Sao Paulo, Brazil, implemented on HEC-RAS, aiming to estimate longterm loads into the reservoir. The data collection period coincided with the drought of 2013-2015 in Southeastern Brazil, which contributed to the critical analysis of the method and results, whose discussion highlights the use of one-dimensional modeling as an effective instrument for validating sediment curves. The transport capacity functions of Laursen-Copeland and Toffaleti have been shown to be applicable to this river system, as well as the bed sorting and armoring methods of Hirano and Thomas-Copeland. The Manning coefficients were considered preliminary and additional field data are encouraged to enhance its adjustment and incorporate greater accuracy in estimating the water surface profile in future work. Besides, methodological recommendations for sediment monitoring are presented, contributing to the systematization of available techniques and technologies applied to sediment research.

Gli stili APA, Harvard, Vancouver, ISO e altri

9

Cruz, Rafael Oscar de Moraes. "Combustão In-Situ = considerações sobre projeto e simulações numéricas em escala de laboratório e de campo". [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264311.

Testo completo

Abstract (sommario):

Orientador: Osvair Vidal Trevisan
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências
Made available in DSpace on 2018-08-17T03:24:53Z (GMT). No. of bitstreams: 1 Cruz_RafaelOscardeMoraes_M.pdf: 2702019 bytes, checksum: 2b9e5d6d733bae790360b90f575601e6 (MD5) Previous issue date: 2010
Resumo: A previsão de comportamento de reservatórios submetidos a combustão in-situ é trabalhosa e empírica já que além das complexidades geológicas, é necessário modelar a complexidade do hidrocarboneto de reservatório e das reações químicas que ocorrem no processo. As etapas de projeto de campo costumam envolver 1) seleção de reservatório; 2) experimentos termo-analíticos; 3) experimentos em tubo de combustão; 4) aplicação de métodos analíticos; 5) simulação numérica; 6) calibração dos modelos analíticos e numéricos através de dados de projeto piloto. O escopo de trabalho desta dissertação está concentrado nas Etapas 4 e 5 deste processo e o foco é a previsão de comportamento de projetos de campo. Propõe-se uma metodologia de mudança de escala para tratamento de dados advindos de laboratório para uso em previsão de comportamento. Adapta-se um equacionamento clássico de projeto de campo de Nelson e Mcneil (1961) para agregar o conceito de velocidade mínima de frente de chama. Para avaliar a extensão dos resultados obtidos com os experimentos em células de combustão 3D de Coates et al (1995) e de Greaves e Turta (2003), que foram realizados para testar as configurações de poço top-down e thai respectivamente, realiza-se simulações em escala de laboratório para reproduzir uma célula de combustão 3D, e avalia-se o impacto de diversos parâmetros de modelagem, como a composição dos fluidos e as reações químicas, além de parâmetros operacionais. Nestas simulações foi possível reproduzir maior complexidade do modelo de fluidos e das reações químicas, incluindo reações de adição de oxigênio e de quebra de cadeia. Foi possível ainda reproduzir a dependência entre estas reações, fazendo com que o combustível para as reações de quebra de cadeia fosse gerado nas reações de adição de oxigênio. Utilizou-se uma malha tão refinada quanto as dimensões da frente de chama, de forma que se controlou a evolução das reações pela temperatura. Para exemplificar a metodologia proposta de mudança de escala e de projeto de campo, utilizou-se os experimentos em tubo de combustão de Gonçalves (2010). Os parâmetros projetados foram aplicados em simulações em escala de campo, onde a evolução das reações químicas foi controlada pela velocidade. Definiu-se uma velocidade mínima para avanço da frente de chama através de tratamento dos dados advindos dos experimentos em tubo de combustão e aplicou-se no modelo de simulação, onde se investigou a capacidade de previsão da evolução da frente de chama em um cenário com propriedades geológicas heterogêneas
Abstract: Behavior forecast of reservoirs subjected to in-situ combustion is hard and empirical since besides geological complexities it is necessary to reproduce complex fluid models and several chemical reactions that are part of the process. The work flow for field project usually involves: 1) reservoir screening; 2) thermo-analytical experiments; 3) combustion tube experiments; 4) use of analytical models; 5) numerical simulation and 6) fitting of analytical and numerical models with field pilot data. The present work concerns the fourth and fifth stages of this process and the focus is behavior forecast of field projects. A methodology for upscaling laboratory results for application in behavior forecast is proposed. The classical Nelson and Mcneil (1961) field project equations are adapted to account for the minimum velocity of the combustion front. In order to evaluate the extension of the results obtained by Coates et al (1995) and Greaves and Turta (2003) with 3D combustion cells, wich were carried to test the thai and top-down well configuration respectively, laboratory scale numerical simulation that reproduces a 3D combustion cell is conducted and the influence of several modeling parameters, such as fluid composition and chemical reactions, is tested, along with operational parameters. In this simulations, a greater complexity in the fluid and reaction model is possible with both oxygen addition and bond scission reactions. It is also possible to model the dependency between reactions, making the reactant of high temperature reactions to be formed in low temperature reactions. A grid refinement in the same size of the combustion front is used and chemical reactions continuity is controlled through temperature. Data from the combustion tube experiments from Gonçalves (2010) are used to exemplify and apply the upscaling and field project methodology. The obtained project parameters are used as input for field scale numerical simulation, where the chemical reactions continuity is controlled through velocity. A minimum combustion front velocity is defined and applied in the simulation model, where the capacity of forecast of the combustion front migration in an heterogeneous geological context is evaluated
Mestrado
Reservatórios e Gestão
Mestre em Ciências e Engenharia de Petróleo

Gli stili APA, Harvard, Vancouver, ISO e altri

10

Hnidei, Stephen D. "Selective withdrawal of a linearly stratified fluid in a triangular reservoir". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/28834.

Testo completo

Abstract (sommario):

The water in most reservoirs is density stratified with depth. This stratification leads to the inhibition of vertical movement, consequently, when water is withdrawn from the reservoir it tends to move in a jet-like layer called a withdrawal layer, towards the sink. By placing the sink at a certain depth, one is able to selectively withdrawal water from a limited range of depths and thus obtain water of a desired quality. Much work has been done in this field by considering a simplified boundary geometry, usually rectangular. However little attention has been given to the effects of accurate boundary geometry. For this thesis, five numerical experiments were conducted for the problem of a two-dimensional, viscous, incompressible, slightly-stratified flow towards a sink in a triangular reservoir.
Science, Faculty of
Mathematics, Department of
Graduate

Gli stili APA, Harvard, Vancouver, ISO e altri

11

Paiva, Hernani Petroni. "Simulação da recuperação de petróleo em reservatórios naturalmente fraturados". [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263726.

Testo completo

Abstract (sommario):

Orientador: Denis José Schiozer
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-20T08:15:37Z (GMT). No. of bitstreams: 1 Paiva_HernaniPetroni_M.pdf: 4091307 bytes, checksum: 9c0f72cc029a22e1f5a96e7587ad9ab5 (MD5) Previous issue date: 2012
Resumo: A recuperação de petróleo em reservatórios naturalmente fraturados apresenta-se como um risco de projeto, sobretudo em sistemas molháveis ao óleo ou com molhabilidade intermediária, já que a simulação utilizando deslocamento por injeção de água indica significativa redução da recuperação. As fraturas representam descontinuidades do meio poroso e possuem efeito capilar e condutividade hidráulica distintos, o que altera sensivelmente o comportamento do escoamento no reservatório, e também os mecanismos físicos envolvidos no processo de recuperação. A simulação de reservatórios fraturados é geralmente realizada com o modelo de dupla porosidade, que está implementado nos principais simuladores comerciais. Neste modelo os processos físicos envolvidos na recuperação são representados pela função de transferência entre matriz e fratura. No entanto, os simuladores comerciais utilizam diferentes funções de transferências com diferentes modelos para representar o processo de recuperação. Neste trabalho, foi construído um simulador de dupla porosidade no qual foram implementadas as funções de transferência de Kazemi et al. (1976), Sabathier et al. (1998) e Lu et al. (2008) para comparação dos resultados de recuperação utilizando deslocamento por injeção de água em sistemas molháveis ao óleo ou com molhabilidade intermediária. A comparação entre as funções de transferência foi realizada para diferentes combinações de processos físicos, mostrando que há significativo aumento de recuperação em sistemas molháveis ao óleo ou com molhabilidade intermediária, especialmente em reservatórios totalmente descontínuos quando o deslocamento ocorre por embebição concorrente, coerentemente com o resultado experimental de Firoozabadi (2000). As funções de transferência implementadas, associadas ao modelo de dupla porosidade, foram também comparadas a simuladores comerciais e a um modelo de fraturas discretas refinado, obtendo-se, entretanto, resultados distintos, mostrando que os diferentes modelos de função de transferência fornecem diferentes resultados. A injeção de água mostrou-se um método de recuperação efetivo mesmo em reservatórios totalmente descontínuos em sistemas molháveis ao óleo ou com molhabilidade intermediária quando há deslocamento por embebição concorrente com gradientes de pressão nos blocos de matriz suficientemente elevados. Os resultados são sensíveis aos parâmetros de caracterização e variam de acordo com o processo físico utilizado. Portanto, a caracterização de reservatórios naturalmente fraturados deve ser realizada levando-se em consideração os fenômenos físicos e os modelos utilizados para representá-los
Abstract: The naturally fractured reservoir recovery is a project risk specially in oil-wet or intermediate-wet systems because of the simulations results under waterflood displacement. Fractures are porous medium discontinuities with distinct capillarity and hydraulic conductivity properties that change the reservoir flow behaviour as well the physical mechanisms acting in petroleum recovery. Double-porosity models are generally used in fractured reservoir simulation and have been implemented in the major commercial reservoir simulators. The physical processes acting in petroleum recovery are represented in double-porosity models by matrix-fracture transfer functions. Commercial simulators have their own transfer function implementations, and as a result different kinetics and final recoveries are attained. In this work, a double porosity simulator was built with Kazemi et al. (1976), Sabathier et al. (1998) and Lu et al. (2008) transfer function implementations and their recovery results compared using waterflood displacement in oil-wet or intermediate-wet systems. The results of transfer function comparisons show recovery improvements in oil-wet or intermediate-wet systems under different physical processes combination, particularly in fully discontinuous porous medium when concurrent imbibition takes place, coherent with Firoozabadi (2000) experimental results. Furthermore, the implemented transfer functions, related to a double-porosity model, were compared to double-porosity commercial simulators models, as well a discrete fracture model with refined grid, showing differences between them. Waterflood can be an effective recovery method even in fully discontinuous media for oil-wet or intermediate-wet systems where concurrent imbibition takes place with high enough pressure gradients across the matrix blocks. These results are sensitive to reservoir characterization parameters whose sensitiveness depends on the physical process employed. Naturally fractured reservoir characterization must consider the physical phenomena occurring during recovery and the models used to represent them
Mestrado
Reservatórios e Gestão
Mestre em Ciências e Engenharia de Petróleo

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Stenerud, Vegard. "Multiscale-Streamline Inversion for High-Resolution Reservoir Models". Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1741.

Testo completo

Abstract (sommario):

The topic of this thesis is streamline-based integration of dynamic data for porous media systems, particularly in petroleum reservoirs. In the petroleum industry the integration of dynamic data is usually referred to as history matching. The thesis starts out by giving an introduction to streamline-based history-matching methods. Implementations and extensions of two existing methods for streamline-based history matching are then presented.

The first method pursued is based on obtaining modifications for streamline-effective properties, which subsequently are propagated to the underlying simulation grid for further iterations. For this method, two improvements are proposed to the original existing method. First, the improved approach involves less approximations, enables matching of porosity, and can account for gravity. Second, a multiscale approach is applied for which the data integration is performed on a hierarchy of coarsened grids. The approach proved robust, and gave a faster and better match to the data.

The second method pursued is the so-called generalized travel-time inversion (GTTI) method, which earlier has proven very robust and efficient for history matching. The key to the efficiency of this method is the quasilinear convergence properties and the use of analytic streamline-based sensitivity coefficients. GTTI is applied together with an efficient multiscale-streamline simulator, where the pressure solver is based on a multiscale mixed finite-element method (MsMFEM). To make the history matching more efficient, a selective work-reduction strategy, based on the sensitivities provided by the inversion method, is proposed for the pressure solver. In addition, a method for improved mass conservation in streamline simulation is applied, which requires much fewer streamlines to obtain accurate production-response curves. For a reservoir model with more than one million grid blocks, 69 producers and 32 injectors, the data integration took less than twenty minutes on a standard desktop computer. Finally, we propose an extension of GTTI to fully unstructured grids, where we in particular address issues regarding regularization and computation of sensitivities on unstructured grids with large differences in cell sizes.

Paper I reprinted with kind permission of Elsevier, sciencedirect.com

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Trindade, Priscilla Basilio Cardoso Barros. "Classificação de estado trófico de reservatórios : estudo de caso : reservatório de Rio Bonito (ES)". Universidade Federal do Espírito Santo, 2011. http://repositorio.ufes.br/handle/10/6159.

Testo completo

Abstract (sommario):

Made available in DSpace on 2016-12-23T14:04:33Z (GMT). No. of bitstreams: 1 Priscilla Basilio parte 1.pdf: 1475473 bytes, checksum: 3d420518d136ce0746e700d4b197ea44 (MD5) Previous issue date: 2011-11-23
O reservatório da Pequena Central Hidrelétrica de Rio Bonito, localizada na bacia do rio Santa Maria da Vitória, um dos principais mananciais de abastecimento da Região Metropolitana da Grande Vitória, recebe aporte de nutrientes provenientes de esgotos domésticos, cultivos agrícolas, granjas e pocilgas. No presente estudo procurou-se analisar as condições do corpo de água, quanto a aspectos relacionados com a eutrofização, para o ano hidrológico outubro de 2008 a setembro de 2009, a partir de resultados de monitoramento bimestral de qualidade de água realizado em pontos situados no seu interior, à montante e à jusante. Foi realizada classificação das águas do reservatório, quanto ao estado trófico, de acordo com diferentes modelos matemáticos e Índices de Estado Trófico (IET), incluindo modelos de Salas e Martino (1991) e da OECD, além de IETs de Carlson e de Lamparelli e da Flórida. O Índice Morfoedáfico foi utilizado para estimativa da concentração natural de fósforo total no reservatório de Rio Bonito. Concluiu-se que diferentes modelos podem resultar em diferentes classificações de níveis de trofia e que o ponto situado a jusante do reservatório apresentou melhores condições qualitativas do que o situado a montante, considerando diversos parâmetros monitorados, indicando que o reservatório está funcionando como uma lagoa de estabilização de tratamento de efluentes
The small hydroelectric reservoir of Rio Bonito, located in the basin of the Santa Maria da Vitória river, Espírito Santo State, Brazil. This river is one of the main water supply sources for Vitória metropolitan region and receives nutrients from sewage, agricultural crops, farms and piggeries. In this study, conditions of the water body were analyzed, considering results from bimonthly water quality monitoring developed during October 2008 to September 2009 hydrological year. Surveys were carried out at 3 (three) points located inside the reservoir and 2 (two) points located upstream and downstream, respectively. The trophic state was classified by using different mathematical models and trophic state index (TSI), including Salas and Martino (1991) and OECD models, and Carlson, Lamparelli and Florida TSI. Morphoedaphic Index (MEI) was used to estimate the total phosphorus "natural" concentration in the reservoir of Rio Bonito. It was concluded that the application different models can result in different trophic levels classifications. It was also concluded that the downstream point presented better water quality condition than the upstream point, considering several parameters monitored, indicating that the reservoir is working as a waste stabilization pond

Gli stili APA, Harvard, Vancouver, ISO e altri

14

Ribeiro, Junior Guilherme Blaitterman. "Simulação numerica de combustão "In-situ" em escala laboratorial". [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264269.

Testo completo

Abstract (sommario):

Orientador: Osvair Vidal Trevisan
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociencias
Made available in DSpace on 2018-08-15T14:40:24Z (GMT). No. of bitstreams: 1 RibeiroJunior_GuilhermeBlaitterman_M.pdf: 3933004 bytes, checksum: 61894f4b90ecb88d0e0c7b05a71ab1ad (MD5) Previous issue date: 2009
Resumo: Como as reservas mundiais de óleo leve estão decrescendo continuamente, campos de óleos pesados podem se tornar uma fonte relevante de energia em um futuro próximo. Combustão "In- Situ" (CIS) é uma promissora técnica de recuperação para este tipo de hidrocarboneto, todavia, complexa de se implementar. Tubos de combustão em escala laboratorial e simulações numéricas são essenciais para o dimensionamento de projetos de campo. Este trabalho relata a modelagem numérica de dois experimentos efetuados em escala de laboratório de processos de CIS com um óleo com 12,8º API advindo de um campo candidato para um projeto piloto no Brasil. O estudo numérico foi desenvolvido utilizando o software comercial da CMG, STARS. O objetivo foi analisar o processo, para um modelo físico correspondente ao tubo de combustão utilizado. O modelo de fluido foi ajustado através de um software comercial para um total de sete componentes, óleo pesado, óleo leve, CO2, O2, N2, H2O e coque. Dois processos de combustão foram investigados, o primeiro é o modelo clássico descrito pelo STARS da CMG e o segundo é baseado no modelo de Marín (2007), constituído de frações SARA (saturados, aromáticos, resinas e asfalteno). Os resultados numéricos foram ajustados de acordo com os dados obtidos do experimento. As conclusões sobre este estudo se referem às influências de cada variável sobre o processo global de CIS, em especial a energia de ativação e a entalpia de reação. Além disso, conclui-se que o modelo de fluido e o modelo de reações são fundamentais no ajuste de histórico, assim como a presença de reações sob altas temperaturas são imprescindíveis para se predizer o deslocamento e comportamento da frente de combustão.
Abstract: As the world reserves of light oil steadily decreases, heavy oil and tar sands resources may be an important source of energy. In situ combustion (ISC) is a promising recovery technique for this type of hydrocarbon, otherwise difficult to produce. Combustion tube laboratory experiments and numerical simulations are essential for the design of field projects. This work reports a numeric modeling of two experiments carried out under laboratory scale of in situ combustion process with a 12.8 ºAPI crude from a field candidate to a pilot project in Brazil. The numerical study was developed using the CMG commercial simulator, STARS. The aim was to analyze the process of the physical model corresponding to the combustion tube used. The fluid model was adjusted by a commercial software to a total of 7 components; heavy oil, light oil, CO2, O2, N2, H2O and coke. Two reactions model were analyzed; one is based on the classic combustion model presented by STARS and the other is based on the reactions model proposed by Marín (2007), made up of SARA (saturates, aromatics, resins, and asphaltenes) fractions. The numerical results were history matched to the data derived from the experiment. The important findings in this study were the influences of each variable on the overall ISC process, specifically the activation energy and the enthalpy reaction. It was concluded that the fluid model and the reaction model are key in the history matching task, as well as, the reactions under high temperatures are fundamental to model the combustion front displacement and behavior.
Mestrado
Reservatórios e Gestão
Mestre em Ciências e Engenharia de Petróleo

Gli stili APA, Harvard, Vancouver, ISO e altri

15

Madani, Hadi. "Application of reservoir simulation and flow routing models to the operation of multi-reservoir system in terms of flood controlling and hydropower’s regulation". Thesis, KTH, Mark- och vattenteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171853.

Testo completo

Abstract (sommario):

Dams are amongst the most important components of water resource systems. In many places the water regulated by and stored in dams is essential to meet the development objectives of water supply, flood control, agriculture (i.e. irrigation and livestock), industry, energy generation and other sectors. Previous studies (Gourbesvive, 2008) indicate that in the next 30 years water use will increase by 50% in the world. By 2025 about 4 billion people will live under conditions of severe water stress. Continuous deterioration in water quality in most developing countries is additional challenge. Therefore, development of priority water infrastructures and improvements of water management have essential and complementary roles in contributing to sustainable growth and energy reduction in developing countries like Sweden. One way of improving water management is through increasing the efficiency of utilization of dam reservoirs (Bosona, 2010). Reservoir operation is a complex task involving numerous hydrological, technical, economical, environmental, institutional and political considerations. There is no general algorithm that covers all type of reservoir operation problems. The choice for techniques usually depends on the reservoir specific system characteristics, data availability, the objectives specified and the constraints imposed. Goal of the mathematical modelling and simulation of a physical system is to provide the user with the relevant information used in design and/or management decision-making. However, in the absence of adequate foresight and planning for adverse impacts, past dam construction has often resulted in devastating effects for ecosystems and the livelihoods of affected communities. In this project with Hec-ResSim simulation model four reservoirs in Ore River Basin and 3 reservoirs in Lule River Basin in different location in Sweden are considered and by new operation rules, model is simulated. With consideration of two high floods event model is calibrated and new operation rules for flood control and hydropower melioration was rendered and suggested.

Gli stili APA, Harvard, Vancouver, ISO e altri

16

Tang, Philip Kwok Fan. "Stochastic Hydrologic Modeling in Real Time Using a Deterministic Model (Streamflow Synthesis and Reservoir Regulation Model), Time Series Model, and Kalman Filter". PDXScholar, 1991. https://pdxscholar.library.pdx.edu/open_access_etds/4580.

Testo completo

Abstract (sommario):

The basic concepts of hydrologic forecasting using the Streamflow Synthesis And Reservoir Regulation Model of the U.S. Army Corps of Engineers, auto-regressive-moving-average time series models (including Greens' functions, inverse functions, auto covariance Functions, and model estimation algorithm), and the Kalman filter (including state space modeling, system uncertainty, and filter algorithm), were explored. A computational experiment was conducted in which the Kalman filter was applied to update Mehama local basin model (Mehama is a 227 sq. miles watershed located on the North Santiam River near Salem, Oregon.), a typical SSARR basin model, to streamflow measurements as they became available in simulated real time. Among the candidate AR and ARMA models, an ARMA(l,l) time series model was selected as the best-fit model to represent the residual of the basin model. It was used to augment the streamflow forecasts created by the local basin model in simulated real time. Despite the limitations imposed by the quality of the moisture input forecast and the design and calibration of the basin model, the experiment shows that the new stochastic methods are effective in significantly improving the flood forecast accuracy of the SSARR model.

Gli stili APA, Harvard, Vancouver, ISO e altri

17

Jesus, José Antonio Oliveira de. "Utilização de modelagem matemática 3D na gestão da qualidade da água em mananciais - aplicação no Reservatório Billings". Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/6/6134/tde-17082006-174447/.

Testo completo

Abstract (sommario):

A modelagem matemática de qualidade da água é uma técnica que tem mostrado excelentes resultados na elaboração de prognósticos da qualidade da água. Em função do uso do solo, das condições hidrometeorológicas e da gestão da infra-estrutura existente, a quantidade e o tipo de poluentes afluentes aos corpos receptores têm uma grande variação, o que, por sua vez, traz implicações à qualidade da água e consequentemente à saúde pública e ao meio ambiente. Modelos matemáticos mais complexos, simulando o escoamento tridimensional em reservatórios, com a capacidade de representar o transporte, circulação e reações de poluentes, embora largamente utilizados em outros países, ainda são pouco difundidos em nosso país. No presente momento a RMSP é palco de diversos programas que visam à melhoria e manutenção da qualidade da água do Alto Tietê. Isto inclui o Projeto Tietê, a ampliação da calha do Tietê, e o programa de proteção de mananciais, todos eles com grande esforço de técnicos nacionais e aporte de recursos por organismos financiadores internacionais como BID, BIRD e JBIC. Tendo isto em mente, e a discussão dos instrumentos definidos no marco regulatório envolvendo as políticas nacional e estadual de recursos hídricos, a avaliação da implantação de modelos matemáticos de qualidade da água mais complexos na realidade nacional, como o aqui proposto, assume grande relevância. Neste trabalho verifica-se a viabilidade da implantação de modelos matemáticos 3D na RMSP, e sua utilização como subsídio à discussão de questões específicas referentes à gestão dos recursos hídricos, as quais dificilmente poderiam ser avaliadas sem sua utilização. A aplicação do modelo 3D no Reservatório Billings, viabilizada através de um acordo de cooperação firmado entre CETESB e BID, fornece subsídios à avaliação das alterações da qualidade da água neste reservatório, em função de questões como, por exemplo, variações nos bombeamentos do Rio Pinheiros e/ou das condições meteorológicas, e evidencia a importância do envolvimento de técnicos de todas as instituições atuantes na gestão do reservatório para o sucesso da utilização da modelagem.
Mathematical modeling has proved to be an extremely useful technique in forecasting water quality. Because of different hydrometeorological conditions and the different ways in which land is used and existing infrastructure is managed, there is considerable variation in the volume and type of pollutant flowing into the receptor bodies. This has implications for water quality and, consequently, public health. More complex mathematical models, simulating three-dimensional reservoir flows and capable of representing pollutant transportation, circulation and reactions, although widely adopted in other countries, are still underutilized in Brazil. Currently, the RMSP is the scene of several programs designed to improve and maintain water quality in the Alto Tiete basin. These include the Tiete Project, the widening of the Tiete River bed and the water source protection program, all of which are being carried out by national specialists with the help of funding from the IDB, the JBIC and the World Bank. Bearing all this in mind, assessing the implementation of more complex mathematical models is imperative for any discussion of the instruments defined by the regulatory framework for federal and state water resource policy. This thesis addresses the feasibility of implementing 3D mathematical models in the RMSP and their utilization as an aid in the discussion of specific water resource management problems, which would be otherwise be difficult to assess. The application of the model to the Billings Reservoir, thanks to a cooperation agreement between CETESB and the IDB, supplies valuable input for the discussion of the models results in evaluating the changes in the reservoirs water quality engendered by such factors as the pumping of water from the Pinheiros River, reservoir segmentation and basin occupation. At the same time it also highlights that if the utilization of such modeling is to be a success, then it is vital that specialists from all the reservoir management institutions are involved.

Gli stili APA, Harvard, Vancouver, ISO e altri

18

Hesterlee, Craig D. "Dynamic modeling of West Point Reservoir hydrothermal and algal growth forcing mechanisms". Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/20732.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

19

McBryde, Emma Sue. "Mathematical and statistical modelling of infectious diseases in hospitals". Queensland University of Technology, 2006. http://eprints.qut.edu.au/16330/.

Testo completo

Abstract (sommario):

Antibiotic resistant pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant enterococci (VRE), are an increasing burden on healthcare systems. Hospital acquired infections with these organisms leads to higher morbidity and mortality compared with the sensitive strains of the same species and both VRE and MRSA are on the rise worldwide including in Australian hospitals. Emerging community infectious diseases are also having an impact on hospitals. The Severe Acute Respiratory Syndrome virus (SARS Co-V) was noted for its propensity to spread throughout hospitals, and was contained largely through social distancing interventions including hospital isolation. A detailed understanding of the transmission of these and other emerging pathogens is crucial for their containment. The statistical inference and mathematical models used in this thesis aim to improve understanding of pathogen transmission by estimating the transmission rates of contagions and predicting the impact of interventions. Datasets used for these studies come from the Princess Alexandra Hospital in Brisbane, Australia and Shanxi province, mainland China. Epidemiological data on infection outbreaks are challenging to analyse due to the censored nature of infection transmission events. Most datasets record the time on symptom onset, but the transmission time is not observable. There are many ways of managing censored data, in this study we use Bayesian inference, with transmission times incorporated into the augmented dataset as latent variables. Hospital infection surveillance data is often much less detailed that data collected for epidemiological studies, often consisting of serial incidence or prevalence of patient colonisation with a resistant pathogen without individual patient event histories. Despite the lack of detailed data, transmission characteristics can be inferred from such a dataset using structured HiddenMarkovModels (HMMs). Each new transmission in an epidemic increases the infection pressure on those remaining susceptible, hence infection outbreak data are serially dependent. Statistical methods that assume independence of infection events are misleading and prone to over-estimating the impact of infection control interventions. Structured mathematical models that include transmission pressure are essential. Mathematical models can also give insights into the potential impact of interventions. The complex interaction of different infection control strategies, and their likely impact on transmission can be predicted using mathematical models. This dissertation uses modified or novel mathematical models that are specific to the pathogen and dataset being analysed. The first study estimates MRSA transmission in an Intensive Care Unit, using a structured four compartment model, Bayesian inference and a piecewise hazard methods. The model predicts the impact of interventions, such as changes to staff/patient ratios, ward size and decolonisation. A comparison of results of the stochastic and deterministic model is made and reason for differences given. The second study constructs a Hidden Markov Model to describe longitudinal data on weekly VRE prevalence. Transmission is assumed to be either from patient to patient cross-transmission or sporadic (independent of cross-transmission) and parameters for each mode of acquisition are estimated from the data. The third study develops a new model with a compartment representing an environmental reservoir. Parameters for the model are gathered from literature sources and the implications of the environmental reservoir are explored. The fourth study uses a modified Susceptible-Exposed-Infectious-Removed (SEIR) model to analyse data from a SARS outbreak in Shanxi province, China. Infectivity is determined before and after interventions as well as separately for hospitalised and community symptomatic SARS cases. Model diagnostics including sensitivity analysis, model comparison and bootstrapping are implemented.

Gli stili APA, Harvard, Vancouver, ISO e altri

20

Thibodeau, Anne-Marie Bechard. "Numerical Model of the Transient Effects of a Heat of Fusion Reservoir Interacting with Two-phase Flow". Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/ThibodeauAMB2002.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

21

McBryde, Emma Sue. "Mathematical and statistical modelling of infectious diseases in hospitals". Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16330/1/Emma_McBryde_Thesis.pdf.

Testo completo

Abstract (sommario):

Antibiotic resistant pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant enterococci (VRE), are an increasing burden on healthcare systems. Hospital acquired infections with these organisms leads to higher morbidity and mortality compared with the sensitive strains of the same species and both VRE and MRSA are on the rise worldwide including in Australian hospitals. Emerging community infectious diseases are also having an impact on hospitals. The Severe Acute Respiratory Syndrome virus (SARS Co-V) was noted for its propensity to spread throughout hospitals, and was contained largely through social distancing interventions including hospital isolation. A detailed understanding of the transmission of these and other emerging pathogens is crucial for their containment. The statistical inference and mathematical models used in this thesis aim to improve understanding of pathogen transmission by estimating the transmission rates of contagions and predicting the impact of interventions. Datasets used for these studies come from the Princess Alexandra Hospital in Brisbane, Australia and Shanxi province, mainland China. Epidemiological data on infection outbreaks are challenging to analyse due to the censored nature of infection transmission events. Most datasets record the time on symptom onset, but the transmission time is not observable. There are many ways of managing censored data, in this study we use Bayesian inference, with transmission times incorporated into the augmented dataset as latent variables. Hospital infection surveillance data is often much less detailed that data collected for epidemiological studies, often consisting of serial incidence or prevalence of patient colonisation with a resistant pathogen without individual patient event histories. Despite the lack of detailed data, transmission characteristics can be inferred from such a dataset using structured HiddenMarkovModels (HMMs). Each new transmission in an epidemic increases the infection pressure on those remaining susceptible, hence infection outbreak data are serially dependent. Statistical methods that assume independence of infection events are misleading and prone to over-estimating the impact of infection control interventions. Structured mathematical models that include transmission pressure are essential. Mathematical models can also give insights into the potential impact of interventions. The complex interaction of different infection control strategies, and their likely impact on transmission can be predicted using mathematical models. This dissertation uses modified or novel mathematical models that are specific to the pathogen and dataset being analysed. The first study estimates MRSA transmission in an Intensive Care Unit, using a structured four compartment model, Bayesian inference and a piecewise hazard methods. The model predicts the impact of interventions, such as changes to staff/patient ratios, ward size and decolonisation. A comparison of results of the stochastic and deterministic model is made and reason for differences given. The second study constructs a Hidden Markov Model to describe longitudinal data on weekly VRE prevalence. Transmission is assumed to be either from patient to patient cross-transmission or sporadic (independent of cross-transmission) and parameters for each mode of acquisition are estimated from the data. The third study develops a new model with a compartment representing an environmental reservoir. Parameters for the model are gathered from literature sources and the implications of the environmental reservoir are explored. The fourth study uses a modified Susceptible-Exposed-Infectious-Removed (SEIR) model to analyse data from a SARS outbreak in Shanxi province, China. Infectivity is determined before and after interventions as well as separately for hospitalised and community symptomatic SARS cases. Model diagnostics including sensitivity analysis, model comparison and bootstrapping are implemented.

Gli stili APA, Harvard, Vancouver, ISO e altri

22

ANDRADE, Patrício Luiz de. "O Problema de Riemann para um modelo matemático de um escoamento trifásico em meio poroso". Universidade Federal de Campina Grande, 2013. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1381.

Testo completo

Abstract (sommario):

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-08-07T21:32:49Z No. of bitstreams: 1 PATRÍCIO LUIZ DE ANDRADE - DISSERTAÇÃO PPGMAT 2013..pdf: 2307465 bytes, checksum: 10af38d3028d3a8ed79ee24d26513d97 (MD5)
Made available in DSpace on 2018-08-07T21:32:49Z (GMT). No. of bitstreams: 1 PATRÍCIO LUIZ DE ANDRADE - DISSERTAÇÃO PPGMAT 2013..pdf: 2307465 bytes, checksum: 10af38d3028d3a8ed79ee24d26513d97 (MD5) Previous issue date: 2013-05
Neste trabalho construímos uma solução do problema de Riemann para um sistema de leis de conservação proveniente da modelagem matemática de um escoamento trifásico num meio poroso representando a propagação de misturas do tipo água-gásóleo num projeto de recuperação de um reservatório petrolífero. Usando métodos analíticos e computacionais encontramos a geometria das curvas de onda sob a condição de entropia de viscosidade, com matriz de viscosidade sendo a identidade. Mostramos que para dados à direita representando misturas próximas de óleo puro, a solução do problema de Riemann consiste genericamente de uma sequência de dois grupos de ondas relacionados às duas famílias caraterísticas, para quaisquer dados à esquerda representando uma mistura água-gás. No entanto, para dados à direita representando misturas ainda com óleo dominante, mas com uma composição maior de água e gás, surge a necessidade de acrescentar um grupo de ondas transicional na sequência que descreve a solução, para um pequeno conjunto de dados à esquerda.
In this work we construct a solution of the Riemann problem for a system of conservation laws arising from the mathematial modeling of a three-phase ow in a porous medium representing the propagation of water-gas-oil mixtures in a recovery project of a petroleum reservoir. Using analytical and computational methods we ndthe geometry of the wave curves under the viscous pro le entropy condition, with theidentity as the viscosity matrix. We show that for the right data representing almost pure oil compositions the solution of the Riemann problem generically consists of a sequence of two wave groups, related to the two characteristics families, for any left data considered representing a water-gas mixture. However, for right data representing mixtures with oil still dominant, but with a larger proportion of gas and water, a transitional wave group is required in the sequen e for a small subset of left data.

Gli stili APA, Harvard, Vancouver, ISO e altri

23

Souza, Grazione de. "Modelagem computacional de escoamentos com duas e três fases em reservatórios petrolíferos heterogêneos". Universidade do Estado do Rio de Janeiro, 2008. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=711.

Testo completo

Abstract (sommario):

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro
Considera-se neste trabalho um modelo matemático para escoamentos com duas e três fases em reservatórios petrolíferos e a modelagem computacional do sistema de equações governantes para a sua solução numérica. Os fluidos são imiscíveis e incompressíveis e as heterogeneidades da rocha reservatório são modeladas estocasticamente. Além disso, é modelado o fenômeno de histerese para a fase óleo via funções de permeabilidades relativas. No caso de escoamentos trifásicos água-óleo-gás a escolha de expressões gerais para as funções de permeabilidades relativas pode levar à perda de hiperbolicidade estrita e, desta maneira, à existência de uma região elíptica ou de pontos umbílicos para o sistema não linear de leis de conservação hiperbólicas que descreve o transporte convectivo das fases fluidas. Como conseqüência, a perda de hiperbolicidade estrita pode levar à existência de choques não clássicos (também chamados de choques transicionais ou choques subcompressivos) nas soluções de escoamentos trifásicos, de difícil simulação numérica. Indica-se um método numérico com passo de tempo fracionário, baseado em uma técnica de decomposição de operadores, para a solução numérica do sistema governante de equações diferenciais parciais que modela o escoamento bifásico água-óleo imiscível em reservatórios de petróleo heterogêneos. Um simulador numérico bifásico água-óleo eficiente desenvolvido pelo grupo de pesquisa no qual o autor está inserido foi modificado com sucesso para incorporar a histerese sob as hipóteses consideradas. Os resultados numéricos obtidos para este caso indicam fortes evidências que o método proposto pode ser estendido para o caso trifásico água-óleo-gás. A técnica de decomposição de operadores em dois níveis permite o uso de passos de tempo distintos para os quatro problemas definidos pelo procedimento de decomposição: convecção, difusão, pressão-velocidade e relaxação para histerese. O problema de transporte convectivo (hiperbólico) das fases fluidas é aproximado por um esquema central de diferenças finitas explícito, conservativo, não oscilatório e de segunda ordem. Este esquema é combinado com elementos finitos mistos, localmente conservativos, para a aproximação dos problemas de transporte difusivo (parabólico) e de pressão-velocidade (elíptico). O operador temporal associado ao problema parabólico de difusão é resolvido fazendo-se uso de uma estratégia implícita de solução (Backward Euler). Uma equação diferencial ordinária é resolvida (analiticamente) para a relaxação relacionada à histerese. Resultados numéricos para o problema bifásico água-óleo em uma dimensão espacial em concordância com resultados semi-analíticos disponíveis na literatura foram reproduzidos e novos resultados em meios heterogêneos, em duas dimensões espaciais, são apresentados e a extensão desta técnica para o caso de problemas trifásicos água-óleo-gás é proposta.
We consider in this work a mathematical model for two- and three-phase flow problems in petroleum reservoirs and the computational modeling of the governing equations for its numerical solution. We consider two- (water-oil) and three-phase (water-gas-oil) incompressible, immiscible flow problems and the reservoir rock is considered to be heterogeneous. In our model, we also take into account the hysteresis effects in the oil relative permeability functions. In the case of three-phase flow, the choice of general expressions for the relative permeability functions may lead to the loss of strict hyperbolicity and, therefore, to the existence of an elliptic region or umbilic points for the system of nonlinear hyperbolic conservation laws describing the convective transport of the fluid phases. As a consequence, the loss of hyperbolicity may lead to the existence of nonclassical shocks (also called transitional shocks or undercompressive shocks) in three-phase flow solutions. We present a new, accurate fractional time-step method based on an operator splitting technique for the numerical solution of a system of partial differential equations modeling two-phase, immiscible water-oil flow problems in heterogeneous petroleum reservoirs. An efficient two-phase water-oil numerical simulator developed by our research group was sucessfuly extended to take into account hysteresis effects under the hypotesis previously annouced. The numerical results obtained by the procedure proposed indicate numerical evidence the method at hand can be extended for the case of related three-phase water-gas-oil flow problems. A two-level operator splitting technique allows for the use of distinct time steps for the four problems defined by the splitting procedure: convection, diffusion, pressure-velocity and relaxation for hysteresis. The convective transport (hyperbolic) of the fluid phases is approximated by a high resolution, nonoscillatory, second-order, conservative central difference scheme in the convection step. This scheme is combined with locally conservative mixed finite elements for the numerical solution of the diffusive transport (parabolic) and the pressure-velocity (elliptic) problems. The time discretization of the parabolic problem is performed by means of the implicit Backward Euler method. An ordinary diferential equation is solved (analytically) for the relaxation related to hysteresis. Two-phase water-oil numerical results in one space dimensional, in which are in a very good agreement with semi-analitycal results available in the literature, were computationaly reproduced and new numerical results in two dimensional heterogeneous media are also presented and the extension of this technique to the case of three-phase water-oil-gas flows problems is proposed.

Gli stili APA, Harvard, Vancouver, ISO e altri

24

Заєць, В. О. "Підвищення ефективності експлуатації підземних сховищ газу в багатопластових покладах". Thesis, Івано-Франківський національний технічний університет нафти і газу, 2015. http://elar.nung.edu.ua/handle/123456789/4729.

Testo completo

Abstract (sommario):

Дисертація присвячена питанням вивчення закономірностей протікання гідрогазодинамічних процесів у пористому середовищі в багатопластовиих підземних сховищах газу для підвищення ефективності експлуатаційних параметрів для якісного прогнозування процесів формування та циклічної експлуатації газосховищ у виснажених газових покладах і водоносних структурах. Математична модель розроблено для оптимізації параметрів циклічної експлуатації багатопластових газосховищ, для розрахунку основного технологічного ланцюга від пласта-колектора до магістрального газопроводу під час процесів нагнітання та відбирання газу. Методи кількісної оцінки об'єму перетікань газу в багатопластових сховищах для визначення добового дебіту газу під час перетікань у свердловинах спільної експлуатації з подальшим визначенням щомісячного обсягу за час існування перетоків вдосконалені. Геогідродинамічний контроль експлуатації багатопластових сховищ розширено, який заснований на уточненні геологічної побудови покрівлі штучного покладу за даними про міграцію газу в осередку його розсіювання, щоб запобігти ризику виникнення негерметичності в ньому. Модель процесу експлуатації сховищ газу пружно-водонапірного режиму розроблена і передбачає закачування буферного й активного об’ємів газу в підземне сховище, яке створене в водоносній структурі, щоб стабілізувати поровий тиск.
Диссертация посвящена вопросам изучения закономерностей протекания гидрогазодинамических процессов в пористой среде в многопластовых подземных хранилищах газа для повышения эффективности эксплуатационных параметров для качественного прогнозирования процессов формирования и циклической эксплуатации газохранилищ в истощенных газовых залежах и водоносных структурах. Анализ результатов исследования в скважинах показал, что имеет место постепенное поступление воды в горизонт, что приводит к уменьшению газонасыщенной залежи. Рассмотрены методы повышения эффективности эксплуатационных параметров газохранилищ. Проведенные геолого-промышленные исследования разрешают качественно прогнозировать основные показатели создаваемого газохранилища, определять направления работ по качественному раскрытию пласта-коллектора и повысить продуктивность скважины. Разработана математическая модель для оптимизации параметров циклической эксплуатации многопластовых газохранилищ, для расчёта основной технической цепи от пласта-коллектора к магистральному газопроводу во время процессов нагнетания и отбора газа. Усовершенствованы методы количественной оценки объёма нагнетания и отбора газа в многопластовых хранилищах для определения суточного дебита газа во время перетекания в скважинах общей эксплуатации, с дальнейшим определением ежемесячного оборота за время существования перетоков. Для оптимизации эксплуатационных режимов при минимальных затратах ресурсов необходимо регулировать объемы нагнетания и отбора газа, что позволит осуществлять как одновременную (общую) эксплуатацию всех объектов, так и только отдельных объектов через скважины, в зоне которых необходимо увеличить или уменьшить объем нагнетания или отбора. При создании и эксплуатации ПСГ в водоносном или истощенном газоносном пласте с целью повышения технико-экономических показателей производят бурение эксплуатационно-нагнетальных, наблюдательных и контрольных скважин, а также строят компрессорную станцию. Расширен гидродинамический контроль эксплуатации многопластовых хранилищ, основанный на уточнении геологического строения кровли штучной залежи за данными о миграции газа в его очаге рассеивания во избежание риска возникновения в нем негерметичности. Разработана модель процесса эксплуатации хранилищ газа. Данный процесс начинается в условиях упруго-водонапорного режима и включает в себя закачивание буферного и активного объёмов газа в подземное хранилище, созданное в водоносной структуре, для стабилизации порового давления при минимальном давлении за время, после которого начинается нейтральный период, длящийся на протяжении времени, необходимом по технологическим и техническим параметрам. После этого начинается период отбора активного объема газа от максимального давления до величины пластового гидростатического давления, после которого наступает нейтральный период. Его длительность определяется путем расчетов. Корректирование процессов производится как после закачивания, так и после периода отбора газа.
The thesis is devoted to the study of hydrogasdynamic processes flowing patterns in porous media of multilayer underground gas storages in order to improve operational parameters for qualitative prediction of the formation processes and cyclic operation of the gas storage facilities in depleted gas fields and aquifer beds. A mathematical model was developed for optimizing the parameters of cyclic operation of multilayer gas storage facilities and to calculate basic process chain from reservoir to gas pipeline during injection and gas withdrawal processes. Were improved the methods of quantitative estimation of the gas crossflow volumes in the multilayer storages to determine daily output of gas during crossflows between wells of joint operation, followed by determination of monthly volume in a time of crossflows existence. Geohydrodynamic control of multilayer storages was expanded, based on refinement of the geological cap construction of artificial deposit according to the data on gas migration in his scattering cell to prevent the risk of leaks in it. Model of the operation process of the gas storage with elastic-water drive mode was developed. It provides for injection of buffer and active gas volumes in the underground storage, created in the aquifer structure, to stabilize its the pore pressure.

Gli stili APA, Harvard, Vancouver, ISO e altri

25

Bansal, Reeshidev 1978. "Seismic characterization of naturally fractured reservoirs". Thesis, 2007. http://hdl.handle.net/2152/3767.

Testo completo

Abstract (sommario):

Many hydrocarbon reservoirs have sufficient porosity but low permeability (for example, tight gas sands and coal beds). However, such reservoirs are often naturally fractured. The fracture patterns in these reservoirs can control flow and transport properties, and therefore, play an important role in drilling production wells. On the scale of seismic wavelengths, closely spaced parallel fractures behave like an anisotropic media, which precludes the response of individual fractures in the seismic data. There are a number of fracture parameters which are needed to fully characterize a fractured reservoir. However, seismic data may reveal only certain fracture parameters and those are fracture orientation, crack density and fracture infill. Most of the widely used fracture characterization methods such as Swave splitting analysis or amplitude vs. offset and azimuth (AVOA) analysis fail to render desired results in laterally varying media. I have conducted a systematic study of the response of fractured reservoirs with laterally varying elastic and fracture properties, and I have developed a scheme to invert for the fracture parameters. I have implemented a 3D finite-difference method to generate multicomponent synthetic seismic data in general anisotropic media. I applied the finite-difference algorithm in both Standard and Rotated Staggered grids. Standard Staggered grid is used for media having symmetry up to orthorhombic (isotropic, transversely isotropic, and orthorhombic), whereas Rotated Staggered grid is implemented for monoclinic and triclinic media. I have also developed an efficient and accurate ray-bending algorithm to compute seismic traveltimes in 3D anisotropic media. AVOA analysis is equivalent to the first-order Born approximation. However, AVOA analysis can be applied only in a laterally uniform medium, whereas the Born-approximation does not pose any restriction on the subsurface structure. I have developed an inversion scheme based on a ray-Born approximation to invert for the fracture parameters. Best results are achieved when both vertical and horizontal components of the seismic data are inverted simultaneously. I have also developed an efficient positivity constraint which forbids the inverted fracture parameters to be negative in value. I have implemented the inversion scheme in the frequency domain and I show, using various numerical examples, that all frequency samples up to the Nyquist are not required to achieve desired inversion results.

Gli stili APA, Harvard, Vancouver, ISO e altri

26

Rijken, Margaretha Catharina Maria. "Modeling naturally fractured reservoirs from experimental rock mechanics to flow simulation /". Thesis, 2005. http://repositories.lib.utexas.edu/bitstream/handle/2152/1708/rijkenm94544.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

27

Pourafshary, Peyman 1979. "A coupled wellbore/reservoir simulator to model multiphase flow and temperature distribution". Thesis, 2007. http://hdl.handle.net/2152/3638.

Testo completo

Abstract (sommario):

Hydrocarbon reserves are generally produced through wells drilled into reservoir pay zones. During production, gas liberation from the oil phase occurs due to pressure decline in the wellbore. Thus, we expect multiphase flow in some sections of the wellbore. As a multi-phase/multi-component gas-oil mixture flows from the reservoir to the surface, pressure, temperature, composition, and liquid holdup distributions are interrelated. Modeling these multiphase flow parameters is important to design production strategies such as artificial lift procedures. A wellbore fluid flow model can also be used for pressure transient test analysis and interpretation. Considering heat exchange in the wellbore is important to compute fluid flow parameters accurately. Modeling multiphase fluid flow in the wellbore becomes more complicated due to heat transfer between the wellbore fluids and the surrounding formations. Due to mass, momentum, and energy exchange between the wellbore and the reservoir, the wellbore model should be coupled with a numerical reservoir model to simulate fluid flow accurately. This model should be non-isothermal to consider the effect of temperature. Our research shows that, in some cases, ignoring compositional effects may lead to errors in pressure profile prediction for the wellbore. Nearly all multiphase wellbore simulations are currently performed using the "black oil" approach. The primary objective of this study was to develop a non-isothermal wellbore simulator to model transient fluid flow and temperature and couple the model to a reservoir simulator called General Purpose Adaptive Simulator (GPAS). The coupled wellbore/reservoir simulator can be applied to steady state problems, such as production from, or injection to a reservoir as well as during transient phenomena such as well tests to accurately model wellbore effects. Fluid flow in the wellbore may be modeled either using the blackoil approach or the compositional approach, as required by the complexity of the fluids. The simulation results of the new model were compared with field data for pressure gradients and temperature distribution obtained from wireline conveyed pressure recorder and acoustic fluid level measurements for a gas/oil producer well during a buildup test. The model results are in good agreement with the field data. Our simulator gave us further insights into the wellbore dynamics that occur during transient problems such as phase segregation and counter-current multiphase flow. We show that neglecting these multiphase flow dynamics would lead to unreliable results in well testing analysis.

Gli stili APA, Harvard, Vancouver, ISO e altri

28

Lakshminarasimhan, Srivatsan. "Study of the flow of and deposition from turbidity currents". Thesis, 2004. http://hdl.handle.net/2152/2059.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

29

Gambús, Ordaz Maika Karen. "A field study to assess the value of 3D post-stack seismic data in forecasting fluid production from a deepwater Gulf-of-Mexico reservoir". Thesis, 2005. http://hdl.handle.net/2152/1548.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

30

Ding, Chunping. "An object-based approach for studying reservoir connectivity". Phd thesis, 1996. http://hdl.handle.net/1885/144185.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

31

Crawley, P. D. "Optimum operating policies for multiple reservoir systems". Thesis, 1990. http://hdl.handle.net/2440/115778.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

32

Dawkrajai, Pinan. "Temperature prediction model for a producing horizontal well". Thesis, 2006. http://hdl.handle.net/2152/2710.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

33

Makoloane, Nkhabu. "Modelling of gas recovery from South African shale reservoirs (focusing on the KWV-1 bore hole in the Eastern Cape Province)". Thesis, 2018. https://hdl.handle.net/10539/26962.

Testo completo

Abstract (sommario):

A research report submitted to the Faculty of Engineering and Built Environment, University of the Witwatersrand, Johannesburg, South Africa, in partial fulfilment of the requirements for the Degree of Master of Science in Engineering, November 2018
The main aim of the study was to develop mathematical flow model of the shale gas at the Karoo Basin of South Africa (SA). The model development incorporates three systems (phases) to form a triple continuum flow model, the phases include matrix (m), natural (NF) and hydraulic fracture (HF). The model was developed from the continuity equation, and the general equations were formed. (0.05�� = 3.90087 × 10−15 ��2�� 2 + 3.90087 × 10−15 ��2�� 2 − 1.95043 × 10−16(20 × 106 − ��), 0.01 �� = 2.00 × 10−15(20 × 106 − ��) − 2.00 × 10−9(20 × 106 − ��) + �� [7.80 × 10−5 �� ] + �� [7.80 × 10−5 �� ] �� [0.1248269 �� ] + 0.1248269(20 × 106 − ��)− 4.98 × 10−4 = �� The model was solved using numerical method technique known as Finite Difference Method (FDM). For each phase a computer program MATLAB was used to plot the pressure gradient. Hydraulic pressure gradient fractures propagate between the distance of 100m and 500m. The model was verified using the data of Barnett Shale. Sensitivity analysis was also performed on the hydraulic permeability, drainage radius and the initial pressure of the reservoir.
XL2019

Gli stili APA, Harvard, Vancouver, ISO e altri

34

Kumar, Munish. "Multiphase flow in reservoir cores using digital core analysis". Phd thesis, 2009. http://hdl.handle.net/1885/150708.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

35

Piyasena, Nelum P. "Reservoir operating rules for urban water supply systems". Thesis, 1998. https://vuir.vu.edu.au/18205/.

Testo completo

Abstract (sommario):

In recent times, a significant shift has emerged throughout the world from planning and construction of water resource projects to the efficient operation of existing systems due to many reasons. The reasons may include the non-availability of water resources for further development, the limited availability of funds for capital works and the spirited lobbying of environmental groups against construction of major water resource projects. Therefore, it is necessary to determine the optimum operating rules for water resource systems. The generalised water supply simulation model (REALM) is been currently used by many water authorities around Australia for planning and operation of urban water supply systems. The operating rules used in REALM are the restriction rules and target storage curves. These operating rules currently in use do not produce the optimum operation and are based on the subjective operator experience. Therefore, the need to determine optimum operating rules in the form of restriction rules and target reservoir curves was important. A general approach was used to produce the 'optimum' operating rules for an urban water supply system. Melbourne water supply system is considered as the case study. An objective methodology and computer software (namely Restrictions and Targets) were developed to derive the operating rules in terms of restriction rules and target storage curves. The restriction rules were derived using a direct search method known as the Hookes and Jeeves method. The objective function used was the maximisation of releases to demand zones. The constraints of current security criteria were considered. A lumped single reservoir and single demand centre approach was used in the study, however, the effects of multi-reservoir interactions such as reservoir evaporation losses, spills from the system, effect of carrier capacity on releases and demand shortfalls were considered implicitly in the approach. The target storage curves were derived using Discrete Differential Dynamic Programming (DDDP), with the objective function of maximisation of releases to demand zones. REALM system data of the Melbourne system was used and therefore all system details incorporated in a planning study of the system were included in DDDP. Water allocation among various parts of the water supply system was done through network linear programming (NLP). REALM is used by Melbourne Water in their planning studies. The Restrictions and Targets software were developed for the Melbourne water system in this study. Both Restrictions and Targets software were used for the Melbourne system using system, streamflow and demand data provided by Melbourne Water (MW) in early 1994. The restriction rules and target storage curves were derived for both static and dynamic demands. The behaviour of the Melbourne system was analysed under the derived and current MW rules using a REALM simulation model of system for the planning period of 1994 to 2026, and a comparison study was performed. The restriction rules derived under both static and dynamic demand analysis performed better than the current MW restriction rules. It was also found that the restriction rules derived from the static demand analysis were consistently better than those of the dynamic demand analysis while the target storage curves derived from DDDP slightly under-performed the MW current target storage curves. Finally, the target curves derived were fine-tuned using simulation results and expert knowledge, and the system behaviour improved significantly. It is recommended that the operating rules (both restriction rule curves and target storage curves) derived from the static demand analysis be used for the Melbourne system for long term operation as Melbourne system cannot be augmented by constructing reservoirs in the MW catchments due to lack of suitable hydrologic sites.

Gli stili APA, Harvard, Vancouver, ISO e altri

36

Welk, Amber Lee. "A contribution towards real-time forecasting of algal blooms in drinking water reservoirs by means of artificial neural networks and evolutionary algorithms". 2008. http://hdl.handle.net/2440/48542.

Testo completo

Abstract (sommario):

Historical water quality databases from two South Australian drinking water reservoirs were used, in conjunction with various computational modelling methods for the ordination, clustering and forecasting of complex ecological data. Techniques used throughout the study were: Kohonen artificial neural networks (KANN) for data categorisation and the discovery of patterns and relationships, recurrent supervised artificial neural networks (RANN) for knowledge discovery and forecasting of algal dynamics and hybrid evolutionary algorithms (HEA) for rule-set discovery and optimisation for forecasting algal dynamics. These methods were combined to provide an integrated approach to the analysis of algal populations including interactions within the algal community and with other water quality factors, which results in improved understanding and forecasting of algal dynamics. The project initially focussed on KANN for the patternising and classification of the historical data to reveal links between the physical, chemical and biological components of the reservoirs. This offered some understanding of the system and relationships being considered for the construction of the forecasting models. Specific investigations were performed to examine past conditions and the impacts of different management regimes, as well as to discover sets of conditions that correspond with specific algal functional groups. RANN was then used to build models for forecasting both Chl-a and the main nuisance species, Anabaena, up to 7 days in advance. This method also provided sensitivity analyses to demonstrate the relationship between input and output variables by plotting the reaction of the output to variations in the inputs. Initially one year from the data set was selected for the testing of a model, as per the split-sample technique. To further test the models, it was later decided to select several years for testing to ensure the models were useful under changed conditions, and that test results were not misleading regarding the models true capabilities. RANN were firstly used to create reservoir specific or ad-hoc models. Later, the models were trained with the merged data sets of both reservoirs to create one model that could be applied to either reservoir. Another method of forecasting was trialled and compared to RANN. HEA was found to be equal or superior to RANN in predictive power, also allowed sensitivity analysis and provided an explicit, portable rule set. The HEA rule sets were initially tested on selected years of data, however to fully demonstrate the models potential, a process for k-fold cross-validation was developed to test the rule-set on all years of data. To further extend the applicability of the HEA rule-set; the idea of rule-based agents for specific lake ecosystem categories was examined. The generality of a rule-based agent means that, after successful validation on several lakes from one category, the agent could then be applied to other water bodies from within that category that had not been involved in the training process. The ultimate test of the rule-based agent for the warm monomictic and eutrophic lake ecosystem category was to be applied to a real-time monitoring and forecasting situation. The agent was fed with online, real-time data from a reservoir that belonged to the same ecosystem category but was not used in the training process. These preliminary experiments showed promising results. It can be concluded that the concept of rulebased agents will facilitate real-time forecasting of algal blooms in drinking water reservoirs provided on-line monitoring of relevant variables has been implemented. Contributions of this research include: (1) to offer insight into the capabilities of 3 kinds of computational modelling techniques applied to complex water quality data, (2) novel applications of KANN including the division of data into separate management periods for comparison of management efficiency, (3) to both qualitatively and quantitatively elucidate relationships between water quality parameters, (4) research toward the development of a forecasting tool for algal abundance 7 days in advance that could be generic for a particular lake ecosystem category and implemented in real-time, and (5) to suggest a thorough testing method for such models (k-fold cross validation).
http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1331584
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

Gli stili APA, Harvard, Vancouver, ISO e altri

37

Welk, Amber Lee. "A contribution towards real-time forecasting of algal blooms in drinking water reservoirs by means of artificial neural networks and evolutionary algorithms". Thesis, 2008. http://hdl.handle.net/2440/48542.

Testo completo

Abstract (sommario):

Historical water quality databases from two South Australian drinking water reservoirs were used, in conjunction with various computational modelling methods for the ordination, clustering and forecasting of complex ecological data. Techniques used throughout the study were: Kohonen artificial neural networks (KANN) for data categorisation and the discovery of patterns and relationships, recurrent supervised artificial neural networks (RANN) for knowledge discovery and forecasting of algal dynamics and hybrid evolutionary algorithms (HEA) for rule-set discovery and optimisation for forecasting algal dynamics. These methods were combined to provide an integrated approach to the analysis of algal populations including interactions within the algal community and with other water quality factors, which results in improved understanding and forecasting of algal dynamics. The project initially focussed on KANN for the patternising and classification of the historical data to reveal links between the physical, chemical and biological components of the reservoirs. This offered some understanding of the system and relationships being considered for the construction of the forecasting models. Specific investigations were performed to examine past conditions and the impacts of different management regimes, as well as to discover sets of conditions that correspond with specific algal functional groups. RANN was then used to build models for forecasting both Chl-a and the main nuisance species, Anabaena, up to 7 days in advance. This method also provided sensitivity analyses to demonstrate the relationship between input and output variables by plotting the reaction of the output to variations in the inputs. Initially one year from the data set was selected for the testing of a model, as per the split-sample technique. To further test the models, it was later decided to select several years for testing to ensure the models were useful under changed conditions, and that test results were not misleading regarding the models true capabilities. RANN were firstly used to create reservoir specific or ad-hoc models. Later, the models were trained with the merged data sets of both reservoirs to create one model that could be applied to either reservoir. Another method of forecasting was trialled and compared to RANN. HEA was found to be equal or superior to RANN in predictive power, also allowed sensitivity analysis and provided an explicit, portable rule set. The HEA rule sets were initially tested on selected years of data, however to fully demonstrate the models potential, a process for k-fold cross-validation was developed to test the rule-set on all years of data. To further extend the applicability of the HEA rule-set; the idea of rule-based agents for specific lake ecosystem categories was examined. The generality of a rule-based agent means that, after successful validation on several lakes from one category, the agent could then be applied to other water bodies from within that category that had not been involved in the training process. The ultimate test of the rule-based agent for the warm monomictic and eutrophic lake ecosystem category was to be applied to a real-time monitoring and forecasting situation. The agent was fed with online, real-time data from a reservoir that belonged to the same ecosystem category but was not used in the training process. These preliminary experiments showed promising results. It can be concluded that the concept of rulebased agents will facilitate real-time forecasting of algal blooms in drinking water reservoirs provided on-line monitoring of relevant variables has been implemented. Contributions of this research include: (1) to offer insight into the capabilities of 3 kinds of computational modelling techniques applied to complex water quality data, (2) novel applications of KANN including the division of data into separate management periods for comparison of management efficiency, (3) to both qualitatively and quantitatively elucidate relationships between water quality parameters, (4) research toward the development of a forecasting tool for algal abundance 7 days in advance that could be generic for a particular lake ecosystem category and implemented in real-time, and (5) to suggest a thorough testing method for such models (k-fold cross validation).
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

Gli stili APA, Harvard, Vancouver, ISO e altri

38

Bruder, Slawa Romana. "Prediction of Spatial-Temporal Distribution of Algal Metabolites in Eagle Creek Reservoir, Indianapolis, IN". Thesis, 2012. http://hdl.handle.net/1805/3043.

Testo completo

Abstract (sommario):

Indiana University-Purdue University Indianapolis (IUPUI)
In this research, Environmental Fluid Dynamic Code (EFDC) and Adaptive- Networkbased Fuzzy Inference System Models (ANFIS) were developed and implemented to determine the spatial-temporal distribution of cyanobacterial metabolites: 2-MIB and geosmin, in Eagle Creek Reservoir, IN. The research is based on the current need for understanding algae dynamics and developing prediction methods for algal taste and odor release events. In this research the methodology for prediction of 2-MIB and geosmin production was explored. The approach incorporated a combination of numerical and heuristic modeling to show its capabilities in prediction of cyanobacteria metabolites. The reservoir’s variable data measured at monitoring stations and consisting of chemical/physical and biological parameters with the addition of calculated mixing conditions within the reservoir were used to train and validate the models. The Adaptive – Network based Fuzzy Inference System performed satisfactorily in predicting the metabolites, in spite of multiple model constraints. The predictions followed the generally observed trends of algal metabolites during the three seasons over three years (2008-2010). The randomly selected data pairs for geosmin for validation achieved coefficient of determination of 0.78, while 2-MIB validation was not accepted due to large differences between two observations and their model prediction. Although, these ANFIS results were accepted, the further application of the ANFIS model coupled with the numerical models to predict spatio-temporal distribution of metabolites showed serious limitations, due to numerical model calibration errors. The EFDC-ANFIS model over-predicted Pseudanabaena spp. biovolumes for selected stations. The predicted value was 18,386,540 mm3/m3, while observed values were 942,478 mm3/m3. The model simulating Planktothrix agardhii gave negative biovolumes, which were assumed to represent zero values observed at the station. The taste and odor metabolite, geosmin, was under-predicted as the predicted v concentration was 3.43 ng/L in comparison to observed value of 11.35 ng/l. The 2-MIB model did not validate during EFDC to ANFIS model evaluation. The proposed approach and developed methodology could be used for future applications if the limitations are appropriately addressed.

Gli stili APA, Harvard, Vancouver, ISO e altri

39

CAI, GUO-CAI, e 蔡國財. "A study on mathematical model of density current in reservoir". Thesis, 1992. http://ndltd.ncl.edu.tw/handle/11599826346456747284.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

40

Gai, Xiuli 1970. "A coupled geomechanics and reservoir flow model on parallel computers". Thesis, 2004. http://hdl.handle.net/2152/1187.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

41

Philip, Zeno George. "Incorporating subcritical crack growth mechanics into natural fracture characterization for improved reservoir simulation". Thesis, 2003. http://hdl.handle.net/2152/860.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

42

Chuang, Chih Wei, e 莊志維. "A study on the modify laterally averaged two dimensional mathematical model for reservoir". Thesis, 1994. http://ndltd.ncl.edu.tw/handle/43450293099464607473.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

43

Crawley, P. D. (Philip David). "Risk and reliability assessment of multiple reservoir water supply headworks systems". 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phc911.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

44

Reinlie, Shinta Tjahyaningtyas. "Analysis of continuous monitoring data and rapid, stochastic updating of reservoir models". Thesis, 2006. http://hdl.handle.net/2152/2625.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

45

Furui, Kenji. "A comprehensive skin factor model for well completions based on finite element simulations". Thesis, 2004. http://hdl.handle.net/2152/1993.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

46

Qiu, Yuan. "Natural fracture modeling and characterization". Thesis, 2002. http://wwwlib.umi.com/cr/utexas/fullcit?p3082887.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

47

Crawley, P. D. (Philip David). "Risk and reliability assessment of multiple reservoir water supply headworks systems / by Philip David Crawley". Thesis, 1995. http://hdl.handle.net/2440/18555.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

48

Strauss, Jonathan Patrick. "Numerical simulation of pressure response in partially completed oil wells". Thesis, 2002. http://hdl.handle.net/10413/3283.

Testo completo

Abstract (sommario):

This work is concerned with the application of finite difference simulation to modelling the pressure response in partially penetrating oil wells. This has relevance to the oil and hydrology industries where pressure behaviour is used to infer the nature of aquifer or reservoir properties, particularly permeability. In the case of partially penetrating wells, the pressure response carries information regarding the magnitude of permeability in the vertical direction, a parameter that can be difficult to measure by other means and one that has a direct influence on both the total volumes of oil that can be recovered and on the rate of recovery. The derivation of the non-linear differential equations that form the basis for multiphase fluid flow in porous media is reviewed and it is shown how they can be converted into a set of finite difference equations. Techniques used to solve these equations are explained, with particular emphasis on the approach followed by the commercial simulation package used in this study. This involves use of Newton's method to linearize the equations followed by application of a pre-conditioned successive minimization technique to solve the resulting linear equations. Finite difference simulation is applied to a hypothetical problem of solving pressure response in a partially penetrating well in an homogenous but anisotropic medium and the results compared with those from analytical solutions. Differences between the results are resolved, demonstrating that the required level of accuracy can be achieved through selective use of sufficiently small grid blocks and time-steps. Residual discrepancies with some of the analytical methods can be traced to differences in the boundary conditions used in their derivation. The simulation method is applied to matching a complex real-life well test with vertical and lateral variation in properties (including fluid saturation). An accurate match can be achieved through judicious adjustment of the problem parameters with the proviso that the vertical permeability needs to be high. This suggests that the recovery mechanism in the oil field concerned can be expected to be highly efficient, something that has recently been confirmed by production results.
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.

Gli stili APA, Harvard, Vancouver, ISO e altri

49

Singh, Ashutosh. "Facility planning and value of information using a tank reservoir model : a case study in reserve uncertainty". Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-05-1230.

Testo completo

Abstract (sommario):

This thesis presents a methodology to incorporate reservoir uncertainties and estimate the loss in project value when facility planning decisions are based on erroneous estimates of input variables. We propose a tank model along with integrated asset development model to simulate the concept selection process. The model endogenizes drilling decisions and includes an option to expand. Key decision variables included in the model are number of pre-drill wells, initial facility capacity and number of well slots. Comparison is made between project value derived under erroneous estimates for reserve size and under an alternate hypothesis. The results suggest loss in project value of up to 40% when reservoir estimates are erroneous. Moreover, both optimistic and pessimistic reserve estimates results in a loss in project value. However, loss in project value is bigger when reserve size is underestimated than when it is overestimated.
text

Gli stili APA, Harvard, Vancouver, ISO e altri

Tesi sul tema "Reservoirs – Mathematical models"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili