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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Computational tools for soft sensing and state estimation

Balakrishnapillai Chitralekha, Saneej Unknown Date
No description available.
32

Computational tools for soft sensing and state estimation

Balakrishnapillai Chitralekha, Saneej 06 1900 (has links)
The development of fast and efficient computer hardware technology has resulted in the rapid development of numerous computational software tools for making statistical inferences. The computational algorithms, which are the backbone of these tools, originate from distinct areas in science, mathematics and engineering. The main focus of this thesis is on computational tools which can be employed for estimating unmeasured variables in a process using all the available prior information. Specifically, this thesis demonstrates the application of a variety of tools for soft sensing of process variables and uncertain parameters of physiochemical process models, using routine data available from the process. The application examples presented in this thesis come from broad areas where process uncertainty is inherent and includes petrochemical processes, mechanical valve actuators, and upstream production processes in petroleum reservoirs. The mathematical models that are employed in different domains vary significantly in their structure and their level of complexity. In the petrochemical domain, the focus was on developing empirical soft sensors which are essentially nonparametric mathematical models identified using routine data from the process. The Support Vector Regression technique was applied for identifying such nonparametric empirical models. On the other hand, in all the other application examples in this thesis the physical parametric models of the process were utilized. The latter application examples, which cover a major portion of this thesis, demonstrate the application of modern state and parameter estimation algorithms which are firmly grounded on Bayesian theory and Monte Carlo techniques. Prior to the chapters on the application of state and parameter estimation techniques, a tutorial overview of the Monte Carlo simulation based state estimation algorithms is provided with an attempt to throw new light on these techniques. The tutorial is aimed at making these techniques simple to visualize and understand. The application case studies serve to illustrate the performance of the different algorithms. All case studies presented in this thesis are performed on processes that exhibit significant nonlinearity in terms of the relationship between the process input variables and output variables. / Process Control
33

Estudo da recupera??o de ?leo por drenagem gravitacional assistida por inje??o de vapor

Barillas, Jennys Lourdes Meneses 22 February 2008 (has links)
Made available in DSpace on 2014-12-17T15:01:45Z (GMT). No. of bitstreams: 1 JennysLMB.pdf: 3002293 bytes, checksum: 3b71773a14bee418fd80243a633d0cc8 (MD5) Previous issue date: 2008-02-22 / Steam assisted gravity drainage process (SAGD) involves two parallel horizontal wells located in a same vertical plane, where the top well is used as steam injector and the bottom well as producer. The dominant force in this process is gravitational. This improved oil recovery method has been demonstrated to be economically viable in commercial projects of oil recovery for heavy and extra heavy oil, but it is not yet implemented in Brazil. The study of this technology in reservoirs with characteristics of regional basins is necessary in order to analyze if this process can be used, minimizing the steam rate demand and improving the process profitability. In this study, a homogeneous reservoir was modeled with characteristics of Brazilian Northeast reservoirs. Simulations were accomplished with STARS , a commercial software from Computer Modelling Group, which is used to simulate improved oil recovery process in oil reservoirs. In this work, a steam optimization was accomplished in reservoirs with different physical characteristics and in different cases, through a technical-economic analysis. It was also studied a semi-continuous steam injection or with injection stops. Results showed that it is possible to use a simplified equation of the net present value, which incorporates earnings and expenses on oil production and expenses in steam requirement, in order to optimize steam rate and obtaining a higher net present value in the process. It was observed that SAGD process can be or not profitable depending on reservoirs characteristics. It was also obtained that steam demand can still be reduced injecting in a non continuous form, alternating steam injection with stops at several time intervals. The optimization of these intervals allowed to minimize heat losses and to improve oil recovery / O processo de drenagem gravitacional com inje??o cont?nua de vapor (SAGD) envolve dois po?os horizontais paralelos localizados em uma mesma vertical, onde o po?o superior ? usado como injetor de vapor e o inferior como produtor. A for?a dominante neste processo ? a gravitacional. Este m?todo de recupera??o avan?ada tem sido demonstrado ser economicamente vi?vel em projetos comerciais de recupera??o de petr?leo pesado e extra pesado, mas ainda n?o foi implementado no Brasil. O estudo desta tecnologia em reservat?rios com caracter?sticas das bacias regionais ? necess?rio para analisar como se ad?qua o processo para minimizar a demanda de vapor obtendo a maior rentabilidade do processo. Neste estudo foi usado um modelo homog?neo com caracter?sticas de reservat?rios do Nordeste Brasileiro. As simula??es foram realizadas em um programa comercial da Computer Modelling Group , o STARS , m?dulo usado para realizar estudos de m?todos de recupera??o avan?ada de reservat?rios de ?leo. Neste trabalho, foi realizada uma otimiza??o do vapor em reservat?rios com diferentes caracter?sticas f?sicas e em diferentes cen?rios, atrav?s de uma an?lise t?cnico-econ?mica. Tamb?m foi estudada a inje??o de vapor semi-cont?nua ou com paradas. Os resultados obtidos mostraram que ? poss?vel utilizar uma equa??o simplificada do valor presente l?quido, que incorpora os ganhos e gastos na produ??o de ?leo e os gastos na inje??o de vapor, para otimizar a demanda do vapor obtendo um maior valor presente l?quido no processo. Observou-se que o m?todo (SAGD) pode ser ou n?o rent?vel dependendo das caracter?sticas do reservat?rio. Encontrou-se tamb?m que a necessidade de vapor pode ainda ser diminu?da utilizando esquemas de inje??o de vapor com paradas em intervalos de tempo otimizados, e isto permitiu minimizar as perdas de calor e melhorar a recupera??o.
34

Estudo da configura??o de po?os no processo de drenagem gravitacional assistida por vapor (SAGD) em reservat?rios do nordeste brasileiro

Fernandes, Glydianne Mara Di?genes 02 September 2016 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-02-10T16:44:40Z No. of bitstreams: 1 GlydianneMaraDiogenesFernandes_TESE.pdf: 3862064 bytes, checksum: fefa5eff9a9888901a0fc8b23ab2f361 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-02-10T21:36:27Z (GMT) No. of bitstreams: 1 GlydianneMaraDiogenesFernandes_TESE.pdf: 3862064 bytes, checksum: fefa5eff9a9888901a0fc8b23ab2f361 (MD5) / Made available in DSpace on 2017-02-10T21:36:27Z (GMT). No. of bitstreams: 1 GlydianneMaraDiogenesFernandes_TESE.pdf: 3862064 bytes, checksum: fefa5eff9a9888901a0fc8b23ab2f361 (MD5) Previous issue date: 2016-09-02 / As novas tecnologias que utilizam a recupera??o avan?ada de petr?leo surgiram da necessidade de se retirar o ?leo que ainda permanece no reservat?rio ap?s a recupera??o prim?ria. O objetivo desses m?todos ? elevar o fator de recupera??o do ?leo. Dessa forma, alguns projetos passam a se tornar vi?veis economicamente quando se utilizam esses m?todos. Os m?todos t?rmicos, dentre eles a inje??o de vapor, promovem a recupera??o do ?leo atrav?s da inser??o de energia t?rmica dentro do reservat?rio. O aumento da temperatura faz com que o ?leo tenha a sua viscosidade reduzida, aumentando assim, seu deslocamento em dire??o aos po?os de produ??o. O processo de drenagem gravitacional assistida por vapor (SAGD) ? um m?todo avan?ado de recupera??o. Sua configura??o apresenta dois po?os horizontais paralelos, um acima do outro. O vapor ? injetado de forma cont?nua ao longo do po?o injetor, em seguida forma-se uma c?mara de vapor que cresce at? encontrar os limites do reservat?rio. Este ?leo tem, ent?o, sua viscosidade reduzida e, pela a??o das for?as gravitacionais, ? drenado em dire??o ao po?o produtor. Neste contexto, esta pesquisa teve como objetivo realizar um estudo de diferentes configura??es de po?os injetores no processo SAGD, considerando os efeitos das perdas de carga e calor no po?o injetor em reservat?rios do nordeste brasileiro. Um planejamento fatorial foi utilizado para verificar a influ?ncia dos par?metros estudados no fator de recupera??o. Foi realizada tamb?m uma an?lise t?cnico econ?mica das configura??es dos po?os injetores com a finalidade de analisar a rentabilidade dos projetos estudados. Para a realiza??o das simula??es num?ricas foi utilizado o simulador t?rmico STARS da CMG (Computer Modelling Group). Os resultados mostraram que os po?os injetores inclinados apresentaram uma menor produ??o em rela??o ? configura??o com po?os horizontais. A configura??o com po?os injetores deslocados em rela??o ao po?o produtor (W-SAGD), para vaz?es de inje??o a partir de 100 ton/dia, levou a forma??o de uma c?mara de vapor maior e mais eficiente. Foi observado tamb?m que a utiliza??o de po?os injetores verticais (V-SAGD), para maiores vaz?es de inje??o de vapor, apresentou uma produ??o acumulada de ?leo menor, por?m, similar ao SAGD com po?o injetor horizontal. Na an?lise econ?mica, o modelo SAGD apresentou os maiores VPLs. / New technologies that use the enhanced oil recovery emerged the need to remove the oil that remains in the reservoir after primary recovery. The goal of these methods is to increase the oil recovery factor. Thus, some projects start to become economically viable when using these methods. The thermal methods, including steam injection, promote the recovery of oil through the thermal energy within the insert reservoir. The increased temperature causes the oil to have its viscosity reduced, thereby increasing its speed towards the production wells. The steam assisted gravity drainage process (SAGD) is an advanced method of recovery. Its configuration has two parallel horizontal wells, one above the other. The steam is injected continuously during the injection well, and then forms a steam chamber which grows to find the limits of the reservoir. This oil is then reduced its viscosity and, by the action of gravitational forces, it is drained toward the producing well. In this context, this study aimed to carry out a study of different configurations of injection wells in SAGD process, considering the effects of load loss and heat in the injection well in the Brazilian northeast reservoirs. A factorial design was used to investigate the influence of the parameters studied in the recovery factor. It also performed an economic analysis of the technical settings of injection wells in order to analyze the profitability of the projects studied. To perform the numerical simulations we used the thermal simulator CMG STARS (Computer Modelling Group). The results showed that the inclined injection wells had a lower production compared to the configuration with horizontal wells. A setting producer injectors offset from the well (W-SAGD) for injection flowrates from 100 ton/day, led to the formation of a vapor chamber larger and more efficient. It was also observed that the use of vertical injection wells (VSAGD), for larger flowrates, showed a lower cumulative production of oil, however, similar to SAGD injector well horizontally. In the economic analysis, the SAGD model showed the highest NPVs.
35

EOS based simulations of thermal and compositional flows in porous media / Simulation compositionnelle thermique d'écoulements en milieux poreux, utilisant une équation d'état

Martin, Petitfrere 12 September 2014 (has links)
Les calculs d'équilibres à triphasiques et quadriphasiques sont au cœur des simulations de réservoirs impliquant des processus de récupérations tertiaires. Dans les procédés d'injection de gaz ou de vapeur, le système huile-gaz est enrichi d'une nouvelle phase qui joue un rôle important dans la récupération de l'huile en place. Les calculs d'équilibres représentent la majeure partie des temps de calculs dans les simulations de réservoir compositionnelles où les routines thermodynamiques sont appelées un nombre conséquent de fois. Il est donc important de concevoir des algorithmes qui soient fiables, robustes et rapides. Dans la littérature peu de simulateurs basés sur des équations d'état sont applicables aux procédés de récupération thermique. A notre connaissance, il n'existe pas de simulation thermique complètement compositionnelle de ces procédés pour des cas d'applications aux huiles lourdes. Ces simulations apparaissent essentielles et pourraient offrir des outils améliorés pour l’étude prédictive de certains champs. Dans cette thèse, des algorithmes robustes et efficaces de calculs d’équilibre multiphasiques sont proposés permettant de surmonter les difficultés rencontrés durant les simulations d'injection de vapeur pour des huiles lourdes. La plupart des algorithmes d'équilibre de phases sont basés sur la méthode de Newton et utilisent les variables conventionnelles comme variables indépendantes. Dans un premier temps, des améliorations de ces algorithmes sont proposées. Les variables réduites permettent de réduire la dimensionnalité du système de nc (nombre de composants) dans le cas des variables conventionnelles, à M (M<<nc), et sont déjà utilisées dans certains simulateurs de réservoirs commerciaux. La méthode de réduction proposée par Nichita and Graciaa (Fluid Phase Equil. 302 (2011) 226-233) est étendue à l'analyse de stabilité et aux calculs d'équilibres multiphasiques. A l'inverse des précédentes méthodes de réduction, les variables ne sont pas bornées. La méthode de Newton nécessite une Hessienne définie positive pour pouvoir être utilisée. D'autres méthodes de minimisations sont testées permettant de s'affranchir de cette contrainte; les méthodes Quasi-Newton et Trust-Region qui garantissent une direction de descente à chaque itération. Ces dernières présentent un grand intérêt puisqu'elles permettent de réaliser des pas supra-linéaires (même lorsque la Hessienne n'est pas définie positive) et quadratiques (Trust-Region) ou proches de quadratiques (Quasi-Newton) dans le cas contraire. Un nouveau vecteur de variables indépendantes est proposé (construit afin d'obtenir une meilleure mise échelle du problème) et utilisé au sein d'un algorithme BFGS modifié. De même, une méthode de Trust-Region est développée pour les problèmes de tests de stabilités et d'équilibres multiphasiques. Ensuite, considérant le fluide comme semi-continu, une méthodologie basée sur une procédure de quadrature Gaussienne est proposée pour calculer mathématiquement les pseudo-composants capables de représenter le comportement du fluide. La méthodologie peut être vue comme une procédure de groupement/dégroupement, applicable pour tout nombre de points de quadratures et toute composition de mélange. Dans une dernière partie, un algorithme général pour le calcul d’équilibre multiphasique est présenté incluant tous les algorithmes développés. Ce dernier est testé et validé contre des données expérimentales et de la littérature. Des simulations triphasiques et quadriphasiques d'injection de CO2 démontrent la capacité du programme à traiter un nombre arbitraire de phases. Des simulations de balayages par la vapeur sont réalisées pour des réservoirs montrant d'importantes hétérogénéités. Finalement, une simulation complètement compositionnelle du processus de Steam Assisted Gravity Drainage est réalisée. A notre connaissance, il s'agit de la première simulation de la sorte pour des cas d'applications d'huiles lourdes. / Three to four phase equilibrium calculations are in the heart of tertiary recovery simulations. In gas/steam injection processes, additional phases emerging from the oil-gas system are added to the set and have a significant impact on the oil recovery. The most important computational effort in many chemical process simulators and in petroleum compositional reservoir simulations is required by phase equilibrium and thermodynamic property calculations. In field scale reservoir simulations, a huge number of phase equilibrium calculations is required. For all these reasons, the algorithms must be robust and time-saving. In the literature, few simulators based on equations of state (EoS) are applicable to thermal recovery processes such as steam injection. To the best of our knowledge, no fully compositional thermal simulation of the steam injection process has been proposed with extra-heavy oils; these simulations are essential and will offer improved tools for predictive studies of the heavy oil fields. Thus, in this thesis different algorithms of improved efficiency and robustness for multiphase equilibrium calculations are proposed, able to handle conditions encountered during the simulation of steam injection for heavy oil mixtures. Most of the phase equilibrium calculations are based on the Newton method and use conventional independent variables. These algorithms are first investigated and different improvements are proposed. Michelsen’s (Fluid Phase Equil. 9 (1982) 21-40) method for multiphase-split problems is modified to take full advantage of symmetry (in the construction of the Jacobian matrix and the resolution of the linear system). The reduction methods enable to reduce the space of study from nc (number of components) for conventional variables to M (M<<nc) and are already used in some commercial reservoir simulators. The reduction method proposed by Nichita and Graciaa (Fluid Phase Equil. 302 (2011) 226-233) is extended to phase stability analysis and multiphase-split calculations. Unlike previous reduction methods, the set of variables is unbounded and the convergence path is the same as in conventional methods using the logarithm of equilibrium constants as variables. The Newton method requires a positive definite Hessian for convergence. Other kinds of minimization methods are investigated which overcome this constraint; the Quasi-Newton and Trust-region methods always guarantee a descent direction. These methods represent an interesting alternative since they can reach supra-linear steps even when the Hessian is non-positive definite, and can reach quadratic steps (Trust-Region) or nearly quadratic steps (Quasi-Newton) otherwise. A new set of independent variables is proposed (designed to ensure a better scaling of the problem) for a modified BFGS (which ensures the positive definiteness of the approximation of the Hessian matrix) algorithm and a Trust-Region method is also proposed for the stability-testing and phase-split problems. Subsequently, by assuming the fluid composition as semi-continuous, a methodology based on a Gaussian quadrature is proposed to mathematically compute a set of pseudo-components capable of representing the fluid behavior. The methodology can be seen as a lumping-delumping procedure, applicable to any number of quadrature points and to any feed distribution. In a last part, a general multiphase flash procedure implementing all the developed algorithms is presented, and tested against experimental and literature data. Three- and four phase CO2 injection simulations demonstrate the capability of the program to handle any number of phases. Simulations of steam flooding are performed for highly heterogeneous reservoirs. Finally, a fully compositional simulation of the steam assisted gravity drainage process is realized. To the best of our knowledge, this is the first simulation of the kind for heavy oil mixtures.
36

Shear-enhanced permeability and poroelastic deformation in unconsolidated sands

Hamza, Syed Muhammad Farrukh 06 November 2012 (has links)
Heavy oil production depends on the understanding of mechanical and flow properties of unconsolidated or weakly consolidated sands under different loading paths and boundary conditions. Reconstituted bitumen-free Athabasca oil-sands samples were used to investigate the geomechanics of a steam injection process such as the Steam Assisted Gravity Drainage (SAGD). Four stress paths have been studied in this work: triaxial compression, radial extension, pore pressure increase and isotropic compression. Absolute permeability, end-point relative permeability to oil & water (kro and krw), initial water saturation and residual oil saturation were measured while the samples deformed. Triaxial compression is a stress path of increasing mean stress while radial extension and pore pressure increase lead to decreasing mean stress. Pore pressure increase experiments were carried out for three initial states: equal axial and confining stresses, axial stress greater than confining stress and confining stress greater than axial stress. Pore pressure was increased under four boundary conditions: 1) constant axial and confining stress; 2) constant axial stress and zero radial strain; 3) zero axial strain and constant confining stress; and 4) zero axial and radial strain. These experiments were designed to mimic geologic conditions where vertical stress was either S1 or S3, the lateral boundary conditions were either zero strain or constant stress, and the vertical boundary conditions were either zero strain or constant stress. Triaxial compression caused a decrease in permeability as the sample compacted, followed by appreciable permeability enhancement during sample dilation. Radial extension led to sample dilation, shear failure and permeability increase from the beginning. The krw and kro increased by 40% and 15% post-compaction respectively for the samples corresponding to lower depths during triaxial compression. For these samples, residual oil saturation decreased by as much as 40%. For radial extension, the permeability enhancement decreased with depth and ranged from 20% to 50% while the residual oil saturation decreased by up to 55%. For both stress paths, more shear-enhanced permeability was observed for samples tested at lower pressures, implying that permeability enhancement is higher for shallower sands. The pore pressure increase experiments showed an increase of only 0-10% in absolute permeability except when the effective stress became close to zero. This could possibly have occurred due to steady state flow not being reached during absolute permeability measurement. The krw curves generally increased as the pore pressure was increased from 0 psi. The increase ranged from 5% to 44% for the different boundary conditions and differential stresses. The kro curves also showed an increasing trend for most of the cases. The residual oil saturation decreased by 40-60% for samples corresponding to shallow depths while it increased by 0-10% for samples corresponding to greater depths. The reservoirs with high differential stress are more conducive to favorable changes in permeability and residual oil saturation. These results suggested that a decreasing mean stress path is more beneficial for production increase than an increasing mean stress path. The unconsolidated sands are over-consolidated because of previous ice loading which makes the sand matrix stiffer. In this work, it was found that over-consolidation, as expected, decreased the porosity and permeability (40-50%) and increased the Young’s and bulk moduli of the sand. The result is sand which failed at higher than expected stress during triaxial compression. Overall, results show that lab experiments support increased permeability due to steam injection operations in heavy oil, and more importantly, the observed reduction in residual oil saturation implies SAGD induced deformation should improve recovery factors. / text
37

Optimization of steam/solvent injection methods: Application of hybrid techniques with improved algorithm configuration

Algosayir, Muhammad M Unknown Date
No description available.
38

The techno-economics of bitumen recovery from oil and tar sands as a complement to oil exploration in Nigeria / E. Orire

Orire, Endurance January 2009 (has links)
The Nigeria economy is wholly dependent on revenue from oil. However, bitumen has been discovered in the country since 1903 and has remained untapped over the years. The need for the country to complement oil exploration with the huge bitumen deposit cannot be overemphasized. This will help to improve the country's gross domestic product (GDP) and revenue available to government. Bitumen is classifled as heavy crude with API (American petroleum Institute) number ranging between 50 and 110 and occurs in Nigeria, Canada, Saudi Arabia, Venezuela etc from which petroleum products could be derived. This dissertation looked at the Canadian experience by comparing the oil and tar sand deposit found in Canada with particular reference to Athabasca (Grosmont, Wabiskaw McMurray and Nsiku) with that in Nigeria with a view of transferring process technology from Canada to Nigeria. The Nigeria and Athabasca tar sands occur in the same type of environment. These are the deltaic, fluvial marine deposit in an incised valley with similar reservoir, chemical and physical properties. However, the Nigeria tar sand is more asphaltenic and also contains more resin and as such will yield more product volume during hydro cracking albeit more acidic. The differences in the components (viscosity, resin and asphaltenes contents, sulphur and heavy metal contents) of the tar sands is within the limit of technology adaptation. Any of the technologies used in Athabasca, Canada is adaptable to Nigeria according to the findings of this research. The techno-economics of some of the process technologies are. x-rayed using the PTAC (petroleum technology alliance Canada) technology recovery model in order to obtain their unit cost for Nigeria bitumen. The unit cost of processed bitumen adopting steam assisted gravity drainage (SAGD), in situ combustion (ISC) and cyclic steam stimulation (CSS) process technology is 40.59, 25.00 and 44.14 Canadian dollars respectively. The unit cost in Canada using the same process technology is 57.27, 25.00 and 61.33 Canadian dollars respectively. The unit cost in Nigeria is substantively lesser than in Canada. A trade off is thereafter done using life cycle costing so as to select the best process technology for the Nigeria oil/tar sands. The net present value/internal rate of return is found to be B$3,062/36.35% for steam assisted gravity drainage, B$I,570124.51 % for cyclic steam stimulation and B$3,503/39.64% for in situ combustion. Though in situ combustion returned the highest net present value and internal rate of return, it proved not to be the best option for Nigeria due to environmental concern and response time to production. The best viable option for the Nigeria tar sand was then deemed to be steam assisted gravity drainage. An integrated oil strategy coupled with cogeneration using MSAR was also seen to considerably amplify the benefits accruable from bitumen exploration; therefore, an investment in bitumen exploration in Nigeria is a wise economic decision. / Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2010.
39

The techno-economics of bitumen recovery from oil and tar sands as a complement to oil exploration in Nigeria / E. Orire

Orire, Endurance January 2009 (has links)
The Nigeria economy is wholly dependent on revenue from oil. However, bitumen has been discovered in the country since 1903 and has remained untapped over the years. The need for the country to complement oil exploration with the huge bitumen deposit cannot be overemphasized. This will help to improve the country's gross domestic product (GDP) and revenue available to government. Bitumen is classifled as heavy crude with API (American petroleum Institute) number ranging between 50 and 110 and occurs in Nigeria, Canada, Saudi Arabia, Venezuela etc from which petroleum products could be derived. This dissertation looked at the Canadian experience by comparing the oil and tar sand deposit found in Canada with particular reference to Athabasca (Grosmont, Wabiskaw McMurray and Nsiku) with that in Nigeria with a view of transferring process technology from Canada to Nigeria. The Nigeria and Athabasca tar sands occur in the same type of environment. These are the deltaic, fluvial marine deposit in an incised valley with similar reservoir, chemical and physical properties. However, the Nigeria tar sand is more asphaltenic and also contains more resin and as such will yield more product volume during hydro cracking albeit more acidic. The differences in the components (viscosity, resin and asphaltenes contents, sulphur and heavy metal contents) of the tar sands is within the limit of technology adaptation. Any of the technologies used in Athabasca, Canada is adaptable to Nigeria according to the findings of this research. The techno-economics of some of the process technologies are. x-rayed using the PTAC (petroleum technology alliance Canada) technology recovery model in order to obtain their unit cost for Nigeria bitumen. The unit cost of processed bitumen adopting steam assisted gravity drainage (SAGD), in situ combustion (ISC) and cyclic steam stimulation (CSS) process technology is 40.59, 25.00 and 44.14 Canadian dollars respectively. The unit cost in Canada using the same process technology is 57.27, 25.00 and 61.33 Canadian dollars respectively. The unit cost in Nigeria is substantively lesser than in Canada. A trade off is thereafter done using life cycle costing so as to select the best process technology for the Nigeria oil/tar sands. The net present value/internal rate of return is found to be B$3,062/36.35% for steam assisted gravity drainage, B$I,570124.51 % for cyclic steam stimulation and B$3,503/39.64% for in situ combustion. Though in situ combustion returned the highest net present value and internal rate of return, it proved not to be the best option for Nigeria due to environmental concern and response time to production. The best viable option for the Nigeria tar sand was then deemed to be steam assisted gravity drainage. An integrated oil strategy coupled with cogeneration using MSAR was also seen to considerably amplify the benefits accruable from bitumen exploration; therefore, an investment in bitumen exploration in Nigeria is a wise economic decision. / Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2010.
40

[en] 4D SEISMIC, GEOMECHANICS AND RESERVOIR SIMULATION INTEGRATED STUDY APPLIED TO SAGD THERMAL RECOVERY / [pt] ESTUDO INTEGRADO DE SÍSMICA 4D, GEOMECÂNICA E SIMULAÇÃO DE RESERVATÓRIOS APLICADO A PROCESSOS DE RECUPERAÇÃO TÉRMICA SAGD

PAUL RICHARD RAMIREZ PERDOMO 26 October 2017 (has links)
[pt] As reservas de óleos pesados têm obtido grande importância devido à diminuição das reservas de óleos leves e ao aumento dos preços do petróleo. Porém, precisa-se de aumentar a viscosidades destes óleos pesados para que possam fluir até superfície. Para reduzir a viscosidade foi escolhida a técnica de recuperação térmica SAGD (Steam Assisted Gravity Drainage) pelos seus altos valores de recobro. A redução da viscosidade é atingida pela transmissão de calor ao óleo pela injeção de vapor, porém uma parte deste calor é transmitida à rocha. Esta transmissão de calor junto com a produção de óleo geram uma variação no estado de tensões no reservatório o que por sua vez geram fenômenos geomecânicos. Os simuladores convencionais avaliam de uma forma muito simplificada estes fenômenos geomecânicos, o que faz necessários uma abordagem mais apropriada que acople o escoamento dos hidrocarbonetos e a transmissão de calor com a deformação da rocha. As mudanças no reservatório, especialmente a variação da saturação, afetam as propriedades sísmicas da rocha, as quais podem ser monitoradas para acompanhar o avanço da frente de vapor. A simulação fluxo-térmica-composicional-geomecânica é integrada à sísmica de monitoramento 4D da injeção de vapor (a través da física de rochas). Existe uma grande base de dados, integrada por propriedades dos fluidos do reservatório (PVT) (usado no arquivo de entrada de simulação de fluxo) e uma campanha de mecânica das rochas. Foram simulados vários cenários geomecânicos considerando a plasticidade e variação da permeabilidade. Foram avaliadas várias repostas geomecânicas e de propriedades de fluidos no pico de pressão e final do processo SAGD. A resposta geomecânica pode ser observada, porém foi minimizada devido à baixa pressão de injeção, sendo o mecanismo de transmissão de calor um fator importante na produção de óleo (pela redução da viscosidade) e a separação vertical entre poços. Foi também significativa à contribuição da plasticidade no aumento da produção de hidrocarbonetos. A impedância acústica foi calculada usando a Equação de substituição de fluidos de Gassmann. Os sismogramas sintéticos de incidência normal (para monitorar o avanço da frente o câmara de vapor) mostraram a área afetada pela injeção de vapor, porém com pouca variação devida principalmente à rigidez da rocha. / [en] The heavy oil reserves have gained importance due to the decreasing of the present light oil reserves. Although it is necessary to reduce the oil viscosity and makes it flows to surface. For its high recovery factor the SAGD (Steam Assited Gravity Drainage) thermal process was selected. The viscosity reduction is achieved by heat transfer from steam to oil, but some part of this heat goes to rock frame. This heat transfer together with oil production change the initial in-situ stress field what creates geomechanical effects. The conventional flux simulators have a very simplified approach of geomechanical effects, so it is necessary to consider a more suitable approach that considers the coupling between oil flux and heat transfer with rock deformation. The changes within the reservoir, specially the saturation change, affect the seismical rock properties which can be used to monitor the steam chamber growth. The flux-thermal geomechanics is integrated to steam chamber monitoring 4D seismic (through the rock physics). There is a great data base, integrated by reservoir fluid properties (PVT) (used in reservoir simulation dataset) and a rock mechanics campaign. Several scenaries were simulated considering the plasticity and permeability variation. Several geomechanical responses and flux properties at peak pressure and end of SAGD process were evaluated. The geomechanical response can be observed, but was minimized due to low steam injection pressure, being the heat transfer an important in oil production (for the viscosity reduction) and the vertical well separation, too. The plasticity has a significant contribution in the increment of oil production. Acoustic impedance was calculated by using Gassmann fluid substitution approach. 2D Synthetic seismograms, normal incidence (to monitor the steam camera front advance), showed the area affected by steam injection, but with little variation due principally to rock stiffness.

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