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1
Davies, R. "Mathematical modelling of in-situ combustion for enhanced oil recovery." Thesis, University of Bath, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383201.
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In-situ combustion is an oil recovery technique in which air, or oxygen enriched air is injected into a reservoir in order to displace the oil. Under suitable conditions the oxygen will burn with part of the oil, raising the temperature of the reservoir and reducing the viscosity of the oil, hence allowing it to flow more easily. A serious problem with mathematical modelling of in-situ combustion is that of flame extinction due to grid block size effects. When modelling a field scale process using finite difference techniques the grid block size will be far larger than the flame length. Since parameters such as temperature and saturations are averaged over a grid block they will be misrepresented in the Arrhenius reaction rate equation, and the flame may die out. The approach taken to overcome the problem is to decouple the flame from a conventional finite difference simulator and solve separately for the reaction rate and flame velocity. This is achieved using a steady state analysis that applies a reduced set of the conservation equations in a moving frame over the flame region, and solves the resulting eigenvalue problem using a shooting method. The reaction rate and flame velocity determined by the steady state analysis are then used to apply the 'thin flame' technique to the conventional simulator. This treats the flame as a moving heat source and displacing pump, travelling through the domain with the velocity obtained by the steady state analysis. The steady - state analysis is compared with experimental results glvmg good agreement for the flame parameters. The thin flame method produces excellent agreement with the conventional simulator on laboratory scale simulations, and on field scale simulations it greatly reduces the problems associated with grid block size effects.
2
Brown, Rebecca L. "The optimisation of heavy oil recovery." Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277115.
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Foroozesh, Jalah. "Mathematical modelling and numerical simulation of carbonated water injection for enhanced oil recovery and CO2 storage." Thesis, Heriot-Watt University, 2015. http://hdl.handle.net/10399/3236.
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Numerical simulation of carbonated water injection (CWI) as an EOR and CO2 storage technique is studied in this thesis. When carbonated water (CO2 saturated water) contacts oil during injection into oil reservoirs, because of higher solubility of CO2 in hydrocarbons compared to water, CO2 will migrate from water into oil phase. Therefore, oil mobility, and in turn oil recovery, will increase. In addition, CO2 can also be stored securely in reservoir during CWI. The compositional simulation approach should be used for simulation of CWI in order to capture the mechanisms and the changes of composition happening during CWI process. However, the conventional compositional approach is based on the assumption of instantaneous thermodynamic equilibrium. That is, it assumes that the CO2 is transferred and distributed between oil and water phases very fast such that the thermodynamic equilibrium state is reached instantaneously. However, the CWI coreflood experiments presented in the literature show that during CWI, the CO2 transfer between water and oil phases happens slowly and therefore, the assumption of instantaneous equilibrium is not valid during the simulation of CWI coreflood experiments. As a result, the available compositional simulators cannot simulate CWI coreflood experiments correctly. Hence, in this thesis, a new compositional simulator is developed, in which the assumption of instantaneous equilibrium is relaxed by including the kinetics of mass transfer. To evaluate the performance of the developed simulator and to explore its generic capability, two different sets of CWI coreflood experiments performed in a water-wet and a mixed-wet (aged) sandstone core are selected from the literature. These coreflood experiments are simulated and studied in detail including the role of oil swelling and wettability alteration during CWI process. The simulator can predict the production profiles of oil, water and CO2; the CO2 storage profile; the differential pressure across the core and the CO2 concentration in oil and water phases. The impacts of dispersion, injection rate and carbonation level on the performance of CWI process are investigated using the developed simulator. The simulator shows that the dispersion effect on oil production is minimal here during the coreflood experiments. It is also shown that at low injection rates and high carbonation levels, higher oil recovery will be obtained by CWI. In addition, at low injection rates, more CO2 can be stored in core during the coreflood experiments with a lower and delayed CO2 production at the core outlet. Moreover, the compositional simulator of ECLIPSE300 (E300) is used to simulate the CWI coreflood experiments and its capability is compared to the capability of the developed simulator. E300 over predicts the oil recovery of CWI coreflood experiments due to the assumption of instantaneous equilibrium made by ECLIPSE 300. A dimensionless number so-called equilibrium number (Ne) is introduced and it is shown that at a specific range of Ne values, the assumption of instantaneous equilibrium made by E300 is acceptable. Accordingly, it is shown that at reservoir-scale, the system will reach the equilibrium state and therefore E300 can be used to simulate the CWI process at reservoir-scale. Based on this, finally, the reservoir-scale simulation of CWI is studied employing the ECLIPSE300 simulator. The impacts of some influential parameters on CWI performance are investigated using the results of reservoir-scale simulation.
4
Dainton, M. P. "Numerical methods for the solution of uncertain differential equations with application in numerical modelling of oil recovery from underground reservoirs." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262009.
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Begum, Najida. "Mathematical modelling of dermatological disease and recovery." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/34312.
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The National Health Service in the UK spends over £1bn every year treating dermatological conditions such as chronic wounds. These wounds exhibit poor vascularisation prone to polymicrobial infections where slow- or non-healing are typical, and spend prolonged periods in the inflammatory stage. Chronic wounds such as leg and foot ulcers develop in patients with illnesses such as diabetes, where circulation is compromised and regular treatment and monitoring are essential. Many management strategies and new therapies have been introduced to combat chronic wounds and include growth factor therapy and skin substitutes. Although one of the greatest concerns is preventing an acute wound becoming chronic, and retrieving the normal healing before amputations are needed. Other dermatological conditions such as psoriasis affects 2–3% of the UK's population and shares some common traits with the wound healing phenomena, however mathematical models in this area are scarce. The thesis proposes a number of new mathematical models, to describe dermatological skin growth and recovery in both the epidermal and dermal membranes.
6
Al-Abbasi, Adel. "Steam-flood modelling." Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383305.
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Mohammadi, Shahrokh. "Stochastic modelling of capillary dominated gas condensate flow in porousmedia." Thesis, Heriot-Watt University, 1993. http://hdl.handle.net/10399/1451.
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Morton, Alison. "Higher order Godunov IMPES compositional modelling of oil reservoirs." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320187.
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Onwuasoanya, Daniel I. "Development and mathematical modelling of affinity system based on novel matrix." Thesis, University of Bath, 1987. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377998.
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Yang, Canghu. "Mathematical modelling of the flow of water and oil through polymer gels." Thesis, Imperial College London, 2001. http://hdl.handle.net/10044/1/11297.
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Mas, Hernandez Elizabeth. "Modelling foam displacement during improved oil recovery with the pressure-driven growth model." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/modelling-foam-displacement-during-improved-oil-recovery-with-the-pressuredriven-growth-model(03d99c27-dd40-4f9d-9ca2-cb581f8e6f6d).html.
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During oil production several processes are used for extracting oil from underground reservoirs at different stages of the production process. After exploiting so called primary recovery, that depends on the “natural” depletion of the reservoir, other techniques are applied in subsequent stages. In tertiary recovery, foam can be injected and used as the displacing fluid. Foams have the capacity to provide a better percentage of recovery compared to other fluids because foams lower gas mobility, permitting a more uniform and efficient sweep of oil in the formation. However foams are complex fluids and the study of their flow within porous systems, like oil reservoirs, is challenging. Therefore the aim of this work is to study the propagation of a foam front within reservoirs in the context of improved oil recovery. The perspective that is adopted here is to use a simple model for foam rheology known as pressure-driven growth, to describe the foam displacement process using numerical simulations and (in some cases) solving the system analytically. The pressure-driven growth model is a limiting case of the viscous froth model, where terms for surface tension and curvature are removed. Taking this particular limiting case has consequences for the numerical solution of the system as the governing equations become far less stable both physically and numerically. An injection strategy called surfactant alternating gas is described by pressure-driven growth, where all resistance to motion in the advance of the foam is assumed to be focused on a region of wet small bubbles (the foam front) forming the interface of the water and gas phases. This front can be considered to be a one-dimensional curve. We then follow the propagation of the foam front over time, obtaining the front location and its shape. For the case of a homogeneous reservoir with constant driving pressure, the foam front is expected to have a convex shape. However, the numerical solution of pressure-driven growth can admit the formation of concavities in the front shape. These prove to be difficult to handle numerically since they focus down into sharp concave corners. As a consequence, robust numerical schemes are needed, and such schemes can be derived informed by the analysis of asymptotic solutions for the process. In order to deal with concavities, a modification is applied to the velocity of concave corners, which is used to recover the expected convex shape for the entire foam front. Other cases of interest arise in the scope of this study, where the development of concavities are expected due to the nature of the processes themselves, rather than being a mere numerical artifact. These are the case when there is surfactant slumping (i.e. downward migration of surfactant), the case when driving pressure is increased part-way through the process, and the case when the reservoir itself is heterogeneous. The pressure-driven growth model can be used in all these cases with the appropriate modifications to front velocities that each case requires within concavities, and spurious behaviour that would otherwise affect numerical results is thereby prevented.
12
Jiang, Dongxiang. "The application of Kriging technique to mathematical modelling of estuarine water quality." Thesis, University of Newcastle Upon Tyne, 1989. http://hdl.handle.net/10443/530.
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It is essential that estuarine modelling and surveying are carried out simultaneously because not only does the latter provide data required by the former but also the former is verified with data from the latter. This study integrates both research subjects from the panoramic point of view, aiming at improving modelling accuracy and reliability and increasing survey efficiency. Partially stratified estuaries are the most difficult types of estuaries to be modelled, in particular, the velocity field in such an estuary. A review of two commonly used methods to determine the velocity field, i. e., theoretical method and empirical method, revealed their inadequacies in real applications. Thus, a new approach using Kriging technique was originated and was tested on a finite element model of water quality. The model was formulated using a Galerkinfinite element method and was programmed in Fortran. Comparison between the simulation results and the field measurements for a salinity intrusion showed a high simulation accuracy. It is believed that the model in combination with the new approach would be a useful tool for estuarine modelling. The generalized Kriging method ensured that the new approach would be appropriate in practice. It was also applied to the investigation of sampling stations in the partially mixed estuary of the River Tees. It is essential to know how many sampling stations should be used and how they should be positioned. Two procedures were designed for solving the survey problems. They were the procedure of overall variance and the procedure of re-estimation. These procedures were capable of quantifing the relative significance of each sampling station and detecting redundant sampling stations. The 1975 survey was investigated, and useful conclusions were obtained.
13
Tchambak, Eric. "Cold heavy oil production using CO2-EOR technique." Thesis, Robert Gordon University, 2014. http://hdl.handle.net/10059/3140.
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This thesis presents results of a successful simulation study using CO2-EOR technique to enable production from an offshore heavy oil field, named here as Omega, which is located offshore West Africa at a water depth around 2000 m. The findings and contributions to knowledge are outlined below: 1. Long distance CO2 transportation offshore – The solution to the space and weight constraints offshore with respect to CO2-EOR, is a tie-back via long distance CO2 dense phase transportation from onshore to offshore. 2. Cold heavy oil production (CHOP) using CO2-EOR technique - Based on conditions investigated, Miscible Displacement was found to be more efficient for deepwater production. However, Immiscible Displacement can offer greater reliability with regards to CO2 sequestration. 3. CO2 sequestration during CHOP using CO2-EOR technique – Lower CO2 may be released post start-up operation, followed by gradual decline of CO2 retention after the production peak. CO2 retention increases with increasing reservoir pressure, starting with 17.7 % retention at 800 psig to 32.8 % at 5000 psig, based on peak production analysis. 4. Techno-economic Evaluation – Miscible displacement is asssociated with higher cash flow stream that extend throughout the lifetime of the asset due to continuous production while Immiscible Displacement has a longer payback period (in order of 22 years) due to the time lag between the CO2 injection and the incremental heavy oil production. 5. Mathematical Modelling – Improved mathematical models based on existing theories are proposed, to estimate the CO2 requirement and heavy oil production during CHOP using CO2-EOR technique, and to provide an operating envelope for a wide range of operating conditions. As part of further work, the proposed models will require more refinement and validation across a broad range of operating conditions, could be adapted and modified to increase its predictive capability over time.
14
Obón, Estrada Eleonora. "Towards the recovery of rare earth elements from end-of-life products : hydrometallurgical routes and mathematical modelling of extraction systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/669262.
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The rare earth elements (REEs) are essential ingredients for the development of modern industry and the transition to a more sustainable economy model. The unique physicochemical features of these elements, such as their magnetism and optical properties, are greatly expanding their application. They have become key elements for the manufacture of many ordinary consumer goods like hybrid cars, fluorescent lamps or electronic devices like mobile phones or tablets. The growing popularity of the rare earth elements derivatives is leading to an increase in the global demand and the price of these elements. Unfortunately, the current availability of these resources is limited due to three main factors: their heterogeneous geological location, their low concentration in the ores, and the environmental issues related with their mining.
All these disadvantages concerning the supply of the rare earth elements have led to the study of new techniques to obtain them, such as the recycling of end-of-life products. Recycling of REEs arises as a new secondary source of supply of REEs, especially in Europe where large amounts of technological waste are generated every year. Currently, the recycling of rare earth elements represents less than 1% of the global supply. Nevertheless, some studies in the literature assume that by 2050 the recovery rate of REEs will be 90% for wind turbines, 70% for electrical vehicles and 40% for the rest of derivative products.
The research presented in this thesis relies on experimental investigation of new hydrometallurgical routes, the majority of them involving the use of ionic liquids, which could eventually be applied for the recovery of rare earth elements from end-of-life products. Matemathical modelling of the reported extraction systems has been carried out in order to provide a computational instrument that can be easily tailored for prediction of other collecting processes requiring minor adjustments.Les terres rares son ingredients essencials per al desenvolupament de la indústria moderna i la transició cap a un model econòmic més sostenible. Les seves característiques físico-químiques úniques, com el seu magnetisme i propietats òptiques, han precipitat un increment accelerat en l’aplicació d’aquests elements. Les terres rares s’han convertit en elements clau per a la fabricació de molts articles d’ús diari com per exemple, cotxes elèctrics i dispositius electrònics com telèfons mòbils i tabletes. La creixent popularitat dels productes que contenen aquests metalls està provocant un escalat en la demanda global i el preu de les terres rares. Desafortunadament, en l’actualitat, la disponibilitat d’aquests recursos a la natura és limitada degut bàsicament a tres factors: heterogènia localització geològica, baixa concentració als minerals que els contenen i inconvenients mediambientals relacionats amb la mineria. Els inconvenients relacionats amb el subministrament de les terres rares a nivell mundial han propiciat l’estudi de noves tècniques per a la obtenció d’aquests elements mitjançant el reciclatge de productes que els contenen. El reciclatge sorgeix com una font secundària alternativa a la mineria per tal d’assegurar el provisionament de terres rares especialment a Europa, on generem grans quantitats de residus tecnològics cada any. Actualment, la taxa de reciclatge de terres rares se situa per sota l'1% del subministrament global. No obstant, alguns estudis publicats en la literatura assumeixen que l’any 2050, la taxa de recuperació haurà augmentat considerablement, de manera que es reciclarà fins a un 90% de les terres rares provinents d’aerogeneradors, 70% de vehicles elèctrics i 40% de la resta de productes que contenen aquests metalls. La recerca presentada en aquesta tesi es basa, principalment, en la investigació de noves rutes hidrometal·lúrgies, la majoria d’elles utilitzant líquids iònics, que puguin ser implementades en processos de recuperació de terres rares a partir de residus tecnològics. D’altra banda, s’han elaborat models matemàtics dels sistemes d’extracció reportats que pretenen convertir-se en una eina computacional, fàcilment adaptable, per a la predicció del comportament d’extracció en d’altres processos de recuperació amb diferents condicions experimentals.
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Tokode, Oluwatosin. "Photocatalytic destruction of volatile organic compounds from the oil and gas industry." Thesis, Robert Gordon University, 2014. http://hdl.handle.net/10059/1134.
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Heterogeneous photocatalysis is an advanced oxidation technology widely applied in environmental remediation processes. It is a relatively safe and affordable technology with a low impact on the environment and has found applications in a number of fields from chemical engineering, construction and microbiology to medicine. It is not catalysis in the real sense of the word as the photons which initiate the desired photocatalytic reaction are consumed in the process. The cost of these photons is by far the limiting economic factor in its application. From a technical standpoint, the inefficient use of the aforementioned photons during the photocatalytic reaction is responsible for the limited adoption of its application in industry. This inefficiency is characterised by low quantum yields or photonic efficiencies during its application. The mechanism of the technique of controlled periodic illumination which was previously proposed as a way of enhancing the low photonic efficiency of TiO2 photocatalysis has been investigated using a novel controlled experimental approach; the results showed no advantage of periodic illumination over continuous illumination at equivalent photon flux. When the technique of controlled periodic illumination is applied in a photocatalytic reaction where attraction between substrate molecules and catalyst surface is maximum and photo-oxidation by surface-trapped holes, {TiIVOH•}+ ads is predominant, photonic efficiency is significantly improved. For immobilized reactors which usually have a lower illuminated surface area per unit volume compared to suspended catalyst and mass transfer limitations, the photonic efficiency is even lower. A novel photocatalytic impeller reactor was designed to investigate photonic efficiency in gas–solid photocatalysis of aromatic volatile organic compounds. The results indicate photonic efficiency is a function of mass transfer and catalyst deactivation rate. The development of future reactors which can optimise the use of photons and maximize photonic efficiency is important for the widespread adoption of heterogeneous photocatalysis by industry.
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Jarullah, Aysar Talib. "Kinetic Modelling Simulation and Optimal Operation of Trickle Bed Reactor for Hydrotreating of Crude Oil. Kinetic Parameters Estimation of Hydrotreating Reactions in Trickle Bed Reactor (TBR) via Pilot Plant Experiments; Optimal Design and Operation of an Industrial TBR with Heat Integration and Economic Evaluation." Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5363.
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Catalytic hydrotreating (HDT) is a mature process technology practiced in the
petroleum refining industries to treat oil fractions for the removal of impurities (such as
sulfur, nitrogen, metals, asphaltene). Hydrotreating of whole crude oil is a new
technology and is regarded as one of the more difficult tasks that have not been reported
widely in the literature. In order to obtain useful models for the HDT process that can
be confidently applied to reactor design, operation and control, the accurate estimation
of kinetic parameters of the relevant reaction scheme are required. This thesis aims to
develop a crude oil hydrotreating process (based on hydrotreating of whole crude oil
followed by distillation) with high efficiency, selectivity and minimum energy
consumption via pilot plant experiments, mathematical modelling and optimization.
To estimate the kinetic parameters and to validate the kinetic models under different
operating conditions, a set of experiments were carried out in a continuous flow
isothermal trickle bed reactor using crude oil as a feedstock and commercial cobaltmolybdenum
on alumina (Co-Mo/¿-Al2O3) as a catalyst. The reactor temperature was
varied from 335°C to 400°C, the hydrogen pressure from 4 to10 MPa and the liquid
hourly space velocity (LHSV) from 0.5 to 1.5 hr-1, keeping constant hydrogen to oil
ratio (H2/Oil) at 250 L/L. The main hydrotreating reactions were hydrodesulfurization
(HDS), hydrodenitrogenation (HDN), hydrodeasphaltenization (HDAs) and
hydrodemetallization (HDM) that includes hydrodevanadization (HDV) and
hydrodenickelation (HDNi).
An optimization technique is used to evaluate the best kinetic models of a trickle-bed
reactor (TBR) process utilized for HDS, HDAs, HDN, HDV and HDNi of crude oil
based on pilot plant experiments. The minimization of the sum of the squared errors
(SSE) between the experimental and estimated concentrations of sulfur (S), nitrogen
(N), asphaltene (Asph), vanadium (V) and nickel (Ni) compounds in the products, is
used as an objective function in the optimization problem using two approaches (linear
(LN) and non-linear (NLN) regression).
The growing demand for high-quality middle distillates is increasing worldwide
whereas the demand for low-value oil products, such as heavy oils and residues, is
decreasing. Thus, maximizing the production of more liquid distillates of very high
quality is of immediate interest to refiners. At the same time, environmental legislation
has led to more strict specifications of petroleum derivatives. Crude oil hydrotreatment
enhances the productivity of distillate fractions due to chemical reactions. The
hydrotreated crude oil was distilled into the following fractions (using distillation pilot
plant unit): light naphtha (L.N), heavy naphtha (H.N), heavy kerosene (H.K), light gas
oil (L.G.O) and reduced crude residue (R.C.R) in order to compare the yield of these
fractions produced by distillation after the HDT process with those produced by
conventional methods (i.e. HDT of each fraction separately after the distillation). The
yield of middle distillate showed greater yield compared to the middle distillate
produced by conventional methods in addition to improve the properties of R.C.R.
Kinetic models that enhance oil distillates productivity are also proposed based on the
experimental data obtained in a pilot plant at different operation conditions using the
discrete kinetic lumping approach. The kinetic models of crude oil hydrotreating are
assumed to include five lumps: gases (G), naphtha (N), heavy kerosene (H.K), light gas
oil (L.G.O) and reduced crude residue (R.C.R). For all experiments, the sum of the
squared errors (SSE) between the experimental product compositions and predicted
values of compositions is minimized using optimization technique.
The kinetic models developed are then used to describe and analyse the behaviour of an
industrial trickle bed reactor (TBR) used for crude oil hydrotreating with the optimal
quench system based on experiments in order to evaluate the viability of large-scale
processing of crude oil hydrotreating. The optimal distribution of the catalyst bed (in
terms of optimal reactor length to diameter) with the best quench position and quench
rate are investigated, based upon the total annual cost.
The energy consumption is very important for reducing environmental impact and
maximizing the profitability of operation. Since high temperatures are employed in
hydrotreating (HDT) processes, hot effluents can be used to heat other cold process
streams. It is noticed that the energy consumption and recovery issues may be ignored
for pilot plant experiments while these energies could not be ignored for large scale
operations. Here, the heat integration of the HDT process during hydrotreating of crude
oil in trickle bed reactor is addressed in order to recover most of the external energy.
Experimental information obtained from a pilot scale, kinetics and reactor modelling
tools, and commercial process data, are employed for the heat integration process
model. The optimization problem is formulated to optimize some of the design and
operating parameters of integrated process, and minimizing the overall annual cost is
used as an objective function.
The economic analysis of the continuous whole industrial refining process that involves
the developed hydrotreating (integrated hydrotreating process) unit with the other
complementary units (until the units that used to produce middle distillate fractions) is
also presented.
In all cases considered in this study, the gPROMS (general PROcess Modelling
System) package has been used for modelling, simulation and parameter estimation via
optimization process.Tikrit University, Iraq
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Khalfalla, Hamza Abdulmagid. "Modelling and optimisation of oxidative desulphurization process for model sulphur compounds and heavy gas oil : determination of rate of reaction and partition coefficient via pilot plant experiment : modelling of oxidation and solvent extraction processes : heat integration of oxidation process : economic evaluation of the total process." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/4247.
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Heightened concerns for cleaner air and increasingly more stringent regulations on sulphur content in transportation fuels will make desulphurization more and more important. The sulphur problem is becoming more serious in general, particularly for diesel fuels as the regulated sulphur content is getting an order of magnitude lower, while the sulphur contents of crude oils are becoming higher. This thesis aimed to develop a desulphurisation process (based on oxidation followed by extraction) with high efficiency, selectivity and minimum energy consumption leading to minimum environmental impact via laboratory batch experiments, mathematical modelling and optimisation. Deep desulphurization of model sulphur compounds (di-n-butyl sulphide, dimethyl sulfoxide and dibenzothiophene) and heavy gas oils (HGO) derived from Libyan crude oil were conducted. A series of batch experiments were carried out using a small reactor operating at various temperatures (40-100 °C) with hydrogen peroxide (H2O2) as oxidant and formic acid (HCOOH) as catalyst. Kinetic models for the oxidation process are then developed based on 'total sulphur approach'. Extraction of unoxidised and oxidised gas oils was also investigated using methanol, dimethylformamide (DMF) and N-methyl pyrolidone (NMP) as solvents. For each solvent, the 'measures' such as: the partition coefficient (KP), effectiveness factor (Kf) and extractor factor (Ef) are used to select the best/effective solvent and to find the effective heavy gas oil/solvent ratios. A CSTR model is then developed for the process for evaluating viability of the large scale operation. It is noted that while the energy consumption and recovery issues could be ignored for batch experiments these could not be ignored for large scale operation. Large amount of heating is necessary even to carry out the reaction at 30-40 °C, the recovery of which is very important for maximising the profitability of operation and also to minimise environmental impact by reducing net CO2 release. Here the heat integration of the oxidation process is considered to recover most of the external energy input. However, this leads to putting a number of heat exchangers in the oxidation process requiring capital investment. Optimisation problem is formulated using gPROMS modelling tool to optimise some of the design and operating parameters (such as reaction temperature, residence time and splitter ratio) of integrated process while minimising an objective function which is a coupled function of capital and operating costs involving design and operating parameters. Two cases are studied: where (i) HGO and catalyst are fed as one feed stream and (ii) HGO and catalyst are treated as two feed streams. A liquid-liquid extraction model is then developed for the extraction of sulphur compounds from the oxidised heavy gas oil. With the experimentally determined KP multi stage liquid-liquid extraction process is modelled using gPROMS software and the process is simulated for three different solvents at different oil/solvent ratios to select the best solvent, and to obtain the best heavy gas oil to solvent ratio and number of extraction stages to reduce the sulphur content to less than 10 ppm. Finally, an integrated oxidation and extraction steps of ODS process is developed based on the batch experiments and modelling. The recovery of oxidant, catalyst and solvent are considered and preliminary economic analysis for the integrated ODS process is presented.
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Tomlin, Toby-Daniel. "Analysis and modelling of jitter and phase noise in electronic systems : phase noise in RF amplifiers and jitter in timing recovery circuits." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2004. http://theses.library.uwa.edu.au/adt-WU2004.0021.
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Timing jitter and phase noise are important design considerations in most electronic systems, particularly communication systems. The desire for faster transmission speeds and higher levels of integration, combined with lower signal levels and denser circuit boards has placed greater emphasis on managing problems related to phase noise, timing jitter, and timing distribution. This thesis reports original work on phase noise modelling in electronic systems. A new model is proposed which predicts the up-conversion of baseband noise to the carrier frequency in RF amplifiers. The new model is validated by comparing the predicted phase noise performance to experimental measurements as it applies to a common emitter (CE), bipolar junction transistor (BJT) amplifier. The results show that the proposed model correctly predicts the measured phase noise, including the shaping of the noise about the carrier frequency, and the dependence of phase noise on the amplifier parameters. In addition, new work relating to timing transfer in digital communication systems is presented. A new clock recovery algorithm is proposed for decoding timing information encoded using the synchronous residual time-stamp (SRTS) method. Again, theoretical analysis is verified by comparison with an experimental implementation. The results show that the new algorithm correctly recovers the source clock at the destination, and satisfies the jitter specification set out by the ITU-T for G.702 signals.
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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.
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Orientador: Osvair Vidal TrevisanDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências
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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
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Morris, Graham Peter. "Parameter recovery in AC solution-phase voltammetry and a consideration of some issues arising when applied to surface-confined reactions." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:1b1d40f3-ef1a-4f64-b500-17ce34630c43.
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A major problem in the quantitative analysis of AC voltammetric data has been the variance in results between laboratories, often resulting from a reliance on "heuristic" methods of parameter estimation that are strongly dependent on the choices of the operator. In this thesis, an automatic method for parameter estimation will be tested in the context of experiments involving electron-transfer processes in solution-phase. It will be shown that this automatic method produces parameter estimates consistent with those from other methods and the literature in the case of the ferri-/ferrocyanide couple, and is able to explain inconsistency in published values of the rate parameter for the ferrocene/ferrocenium couple. When a coupled homogeneous reaction is considered in a theoretical study, parameter recovery is achieved with a higher degree of accuracy when simulated data resulting from a high frequency AC voltammetry waveform are used. When surface-confined reactions are considered, heterogeneity in the rate constant and formal potential make parameter estimation more challenging. In the final study, a method for incorporating these "dispersion" effects into voltammetric simulations is presented, and for the first time, a quantitive theoretical study of the impact of dispersion on measured current is undertaken.
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Porto, Paulo Sergio da Silva. "Investigações sobre a secagem de particulas de xisto." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267608.
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Orientador: Antonio Carlos Luz LisboaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Xisto pirobetuminoso é uma rocha sedimentar que contém querogênio, um material orgânico que se encontra disseminado em sua estrutura mineral. O querogênio é extraído por aquecimento a altas temperaturas, em reatores conhecidos como retortas, 1iberando óleo e gás. Este óleo quando refinado produz destilados com as mesmas características encontradas nos de petróleo, sendo considerado uma fonte de energia alternativa. A existência de umidade no xisto na entrada do reator gera uma zona de secagem influenciando na redução da temperatura dos gases e diminuição da eficiência da retorta. O objetivo deste trabalho é investigar a perda de umidade durante a secagem de partículas de xisto, visando conhecer os mecanismos envolvidos. Para obter o perfil de umidade ao longo do tempo foram utilizadas partículas classificadas em três diferentes lotes quanto ao diâmetro médio de partícula (dp): partículas individuais do Lote A (dp = 80 mm e dp = 60 mm); partículas do Lote B que subdivide-se em quatro sublotes (~ = 5,3 mm, dp = 3 mm, dp = 1,5 mm e dp = 0,85 mm) e partículas do Lote C (dp < 0,074 mm). Os experimentos de secagem foram realizados em diversos secadores: partículas do Lote A secas em estufa com circulação de ar a 60°C e 90°C; partículas do Lote B secas em bandeja termogravimétrica a 40°C, 60 °c, 80°C e 100°C e em leito de jorro e leito fluidizado a 50°C e 70°C; partículas do Lote C secas em um analisador termogravimétrico, cujas temperaturas iniciais de 20°C variaram ao longo do tempo até atingir valores máximos de 40 °C, 70°C e 100°C. Exceto os experimentos realizados no ana1isador termogravimétrico, em todos os demais a temperatura foi mantida constante. Utilizou-se o modelo matemático de difusão de Fick, considerando geometrias uni e tri-dimensionais. Na solução destes modelos foram desenvolvidos programas em linguagem Fortran para descrever a variação de umidade das partículas de xisto ao longo do tempo e da posição, levando-se em conta a geometria da partícula e a temperatura do ar de secagem (constante ou variável). Os resultados preditos pelos modelos foram comparados com os experimentais apresentando boa concordância. Estes modelos podem contribuir na estimativa de parâmetros desconhecidos do processo. Quanto ao leito em jorro e leito fiuidizado, verificou-se que são técnicas adeqüadas para a secagem de xisto
Abstract: Oil shale is a sedimentary rock which contains kerogen, an organic matter scattered througout a mineral matrix. Kerogen is extracted by pyrolysis at high temperatures in reactors known as retorts producing oil and gas. The oil, when refined, produces distillates with the same characteristics as petroleum. Oil shale is considered an alternative energy source to petroleum. At the top of a moving bed retort oil shale moisture vaporization consumes energy, thereby reducing the retort efficiency. Oil shale drying has been investigated to optimize pyrolysis. The objective of this work was to investigate the moisture loss during oil shale particles drying to know the mechanisms involved. In order to obtain the moisture profile with time particles classified in three different categories
Doutorado
Engenharia de Processos
Doutor em Engenharia Química
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Deschamps, Rémy. "Architectures et facteurs de contrôle des systèmes fluviatiles et turbiditiques. De la caractérisation à la modélisation." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS611.
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Les systèmes turbiditiques et fluviatiles présentent des similitudes, notamment dans leur morphologie (incisions, chenaux), mais de nombreuses différences sont notables, en ce qui concerne l’architecture des dépôts, et l’évolution spatio-temporelle de ces deux systèmes, pourtant génétiquement liés. La comparaison de ces systèmes porte sur l’interaction des différents processus physiques impliqués dans la mise en place et dans le fonctionnement de ces systèmes, et sur les architectures des dépôts préservés. Les systèmes continentaux et marins profonds sont caractérisés d’abord par les processus physiques conduisant à l’érosion, au transport puis au dépôt des particules sédimentaires. Ces processus sont contrôlés par divers forçages locaux ou globaux, façonnant ainsi leurs morphologies qui évolue dans l’espace (le long du profil amont-aval), et dans le temps. Ces systèmes sont génétiquement liés et l’approche « source-to-sink » comprends l’ensemble des processus continentaux et marins qui contribuent à la production, au transport et au dépôt des sédiments. La compréhension de ces facteurs de contrôles est essentielle pour comprendre et prédire la sédimentation enregistrée dans les bassins à différentes échelles. L’ensemble de ces paramètres est responsable de l’organisation interne des réservoirs sableux, et la compréhension de ces différents paramètres vont permettre de contraindre les modèles numériques, dont l’objectif est, selon l’échelle considérée (bassin ou réservoir), de prédire la distribution des faciès sédimentaires (réservoirs, roches mères, couvertures), ou de minimiser les risques lors de l’exploitation d’un réservoirThe turbiditic and fluvial systems have similarities, in particular in their morphology (incisions, channels), but many differences are notable, as regards the architecture of the deposits, and the spatio-temporal evolution of these two systems, yet genetically linked. The comparison of these systems concerns the interaction of the different physical processes involved in the origin and the behaviour of these systems, and on the architectures of the preserved deposits. Continental and deep sea systems are characterized primarily by the physical processes leading to the erosion, transport and subsequent deposition of sedimentary particles. These processes are controlled by various local or global forcing, thus shaping their morphologies that evolves in space (along the upstream-downstream profile), and over time. These systems are genetically linked and the "source-to-sink" approach includes all the continental and marine processes that contribute to sediment production, transport and deposition. Understanding these controlling factors is crucial in the understanding and the prediction of sedimentation recorded in basins, at different scales. The allocyclic and the autocyclic controlling factors are responsible for the internal organization of the sandy reservoirs, and the understanding of these different parameters will make it possible to constrain the numerical models, whose objective is, according to the scale considered (basin scale or reservoir scale), to predict the distribution of sedimentary facies (reservoirs, source rocks, seals), or to minimize the risks when producing a reservoir
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Cave, Vanessa M. "Statistical models for the long-term monitoring of songbird populations : a Bayesian analysis of constant effort sites and ring-recovery data." Thesis, St Andrews, 2010. http://hdl.handle.net/10023/885.
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Kropáč, Jiří. "Pokročilý výpočtový nástroj pro návrh systému čištění spalin z procesu termického zpracování odpadů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-233991.
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The thesis describes the development of a computational tool that allows sophisticated analysis and design of flue gas cleaning technologies for thermal treatment of waste. The assessment of a technological composition of the process in terms of energy consumption, temperature of the flue gas stream and ensuring the fulfilment of emission limits allows estimating the influence of flue gas cleaning system on parameters of an up-to-date waste incinerator. The work is based on an already created computational system. Its output will be integrated into a software system with a user-friendly interface. Creation of the computational system is based on the performed research in the given area. The work presents sets of operational values and relationships describing current technologies used to reduce harmful emissions in the flue gas from thermal treatment of waste.
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Paiva, Hernani Petroni. "Simulação da recuperação de petróleo em reservatórios naturalmente fraturados." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263726.
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Orientador: Denis José SchiozerDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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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
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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.
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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.
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Barbosa, Nelson Machado. "Resolução numérica de equações diferenciais parciais hiperbólicas não lineares: um estudo visando a recuperação de petróleo." Universidade do Estado do Rio de Janeiro, 2010. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=1290.
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Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de JaneiroO processo de recuperação secundária de petróleo é comumente realizado com a injeção de água no reservatório a fim de manter a pressão necessária para sua extração. Para que o investimento seja viável, os gastos com a extração têm de ser menores do que o retorno financeiro obtido com o petróleo. Para tanto, tornam-se extremamente importantes as simulações dos processos de extração. Neste trabalho são estudados os problemas de Burgers e de Buckley-Leverett visando o escoamento imiscível água-óleo em meios porosos, onde o escoamento é incompressível e os efeitos difusivos (devido à pressão capilar) são desprezados. Com o objetivo de incorporar conhecimento matemático mais avançado, para em seguida utilizá-lo no entendimento do problema estudado, abordou-se com razoável profundidade a teoria das leis de conservação. Foram consideradas soluções fracas que, fisicamente, podem ser interpretadas como ondas de choque ou rarefações, então, para que fossem distinguidas as fisicamente admissíveis, foi utilizado o princípio de entropia, nas suas diversas formas. Inicialmente consideramos alguns exemplos clássicos de métodos numéricos para uma lei de conservação escalar, os quais podem ser vistos como esquemas conservativos de três pontos. Entre eles, o método de Lax-Friedrichs (LF) e o método de Lax-Wendroff (LW). Em seguida, um esquema composto foi testado, o qual inclui na sua formulação os métodos LF e LW (chamado de LWLF-4). Respeitando a condição CFL, foram obtidas soluções numéricas de todos os problemas tratados aqui. Com o objetivo de validar tais soluções, foram utilizadas soluções analíticas oriundas dos problemas de Burgers e Buckley- Leverett. Também foi feita uma comparação com os métodos do tipo TVDs com limitadores de fluxo, obtendo resultado satisfatório. Vale à pena ressaltar que o esquema LWLF-4, pelo que nos consta, nunca foi antes utilizado nas resoluções das equações de Burgers e Buckley- Leverett.
The secondary recovery of petroleum is usually performed with injection of water through an oil reservoir to keep the oil pressure for the exploration. In order to make the exploration profitable, the extraction cost must be less than the financial return, which means that the simulation of the exploration process is extremely relevant. In this work, the Burgers- and- Buckley-Leverett problems are studied seeking a two-phase displacement in porous media. The flow is considered incompressible and capillary effects are ignored. In order to analyze the problem, it was necessary to use the theory of conservation law in a spatial variable. Weak solutions, which can be understood as shock or rarefaction waves, are studied with the entropy condition, so that only the physically correct solutions are considered. Some classical numerical methods, which can be seen as conservative schemes of three points, are studied, among them the Lax-Friedrichs (LF) and Lax-Wendroff (LW) methods. A composite scheme, called LWLF-k, is tested using LF and LW methods, being respected the CFL condition, with satisfactory results. In order to validate the numerical schemes, we consider analytical solutions of the Burgers-and-Buckley-Leverett equations. Was also made a comparison with TVDs methods with flux limiters, obtaining satisfactory results. We emphasize that to the best of our knowledge, the LWLF-4 scheme has never been used to solve the Buckley-Leverett equation.
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Wopara, Onuoha Fidelis. "Pore network modelling of wettability effects on waterflood oil recovery from Agbada sandstone formation in the Niger Delta, Nigeria." Thesis, 2016. http://hdl.handle.net/10539/21150.
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A thesis Submitted to the School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Doctor of Philosophy
Johannesburg, 2016Wettability of a porous reservoir rock is an important factor that affects oil recovery during waterflooding. It is recognized as being important for multiphase properties. Understanding the variation of these properties in the field, due to wettability trends and different pore structures, is very critical for designing efficient and reliable processes and projects for enhanced hydrocarbon recovery. After primary drainage the reservoir wettability changes: if it was oil-wet initially, it gradually changes to water-wet during waterflooding. This change in reservoir wettability towards water-wet will reduce the residual oil saturation and improve the oil displacement efficiency. However, knowledge of the constitutive relationship between the pore scale descriptors of transport in the porous system is required to adequately describe wettability trend and its impact on oil recovery, particularly during waterflooding. In this work, the petrophysical properties that define fluid flow in the Agbada, Nigeria sandstone reservoir were determined using conventional experimental and x-ray CT scanning methods. Experimentally measured average porosity is 0.28, average permeability is 1699 mD, while the initial and irreducible water saturation is 0.22. Permeability in the x, y and z directions, ranging from 50 to 200 mD, were calculated from the pore network extracted from the Agbada sandstone rock. Results obtained from the Amott-Harvey wettability measurement method indicate that the reservoir is strongly water-wet, with Amott-Harvey index of about 0.9. The cross-over between the water and oil relative permeabilities occurred at saturations of the samples above 0.5, giving an indication of strong water-wetness. The work summarizes the mechanism of wettability alteration and characterizes the performance of the reservoir during waterflooding from injecting water, and relates the residual oil saturation, relative permeability and volumes of water injected to wettability and its effects on oil recovery. Waterflood oil recovery is computed using the Buckley-Leverett method based on the reservoir rock and fluid properties. Computed waterflood oil recovery using this method was about 60% of the oil initially in place. Plots of spontaneous imbibition rate show that the injection rate for optimal oil recovery is 40 bbls of injected water per day. At this rate, both the mobility and shock front mobility ratios are less than 1, leading to a stable flood front and absence of viscous fingering. Waterflooding is by far the most widely applied method of improved oil recovery over the years with good results in conventional and unconventional (tight oil) reservoirs It is relatively simple and cost effective: abundance and availability of water. Waterflood oil recovery factor is affected by internal and external factors. The placement of the injection and production wells, for example, impacts on the effectiveness of the waterflooding process. I considered the placement of the wells in a five-spot pattern as elements of an unbounded double periodic array of wells and assumed the reservoir to be homogeneous, infinite and isotropic, with constant porosity and permeability. Both fluids are treated as having slight but constant compressibility and their flow governed by Darcy’s law. The average pressure in the reservoir satisfies quasi-static flow or diffusion equation. I then assumed piston-like displacement of oil by injected water that takes account of viscosity diffence between both fluids and proposed a model based on the theory of elliptic functions, in particular Weierstrass p-functions functions. Oil-water contact movement, dimensionless time for water breakthrough at the production well, areal sweep and average reservoir pressures were modeled. The model was tested using Wolfram Mathematica 10 software and the results are promising. The thesis has therefore established that the Agbada sandstone reservoir is strongly water-wet and that waterflooding is a viable option for enhanced oil recovery from the reservoir.
MT2016
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Cheng, Liang 1971. "Modeling and simulation studies of foam processes in improved oil recovery and acid-diversions." Thesis, 2002. http://hdl.handle.net/2152/30212.
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Xu, Qiang. "Theoretical and experimental study of foam for enhanced oil recovery and acid diversion." Thesis, 2003. http://wwwlib.umi.com/cr/utexas/fullcit?p3116241.
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Emera, Mohammed Kamal. "Modelling of CO2 and green-house gases (GHG) miscibility and interactions with oil to enhance the oil recovery in gas flooding processes." 2006. http://hdl.handle.net/2440/60566.
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1. Objective: The objective of this research has been to develop more reliable models to predict the miscibility and interactions between CO₂ or green-house gas (GHG) and oil (dead and live oils) over a wider range of conditions, based on data from different site sources, considering all the major variables affecting each modelled parameter, and for different injected gas compositions. The Genetic algorithm (GA), an artificial intelligence technique based on the Darwinian theory of evolution that mimics some of the natural processes in living organisms, was used to develop these models, based on GA software that has been developed in this work (as a modelling technique). While applications of GA have been used recently in the mathematical and computer sciences, its applications in the petroleum engineering, especially EOR research, have been limited. 2. Motivation to Investigate the Potential of GA-based Models: The detrimental effects of CO₂ and/or GHG emissions from various industrial and human/activity sources on the environment are a major concern worldwide. This has resulted in an intensive global R&D effort to lower or mitigate the damaging impact of GHG on the environment. One potentially attractive and effective means of lowering the GHG emissions could be to capture them from their major sources of emissions and then sequester them in depleted oil and gas reservoirs while also enhancing oil recovery. Typically, a GHG stream, also referred to as "flue gas", contains high percentages of CO₂ in addition to other gases, notably, N₂, NOₓ and SOₓ. The presence of high CO₂ content in the flue gas, in particular, could make this option potentially viable, provided the miscibility and interaction properties between the injected gas and reservoir fluids are favorable. Therefore, it is critical to ascertain the likely miscibility and interactions parameters between the injected gas (CO₂ or flue gas) and oil at different conditions to determine the optimal miscibility and interaction conditions that contribute to oil viscosity reduction and oil swelling. They in turn enhance oil recovery through improved gas flooding process performance due to higher oil mobility, volumetric sweep efficiency, and relative permeability to oil. Often miscibility and interactions between injected gases and oils are established through "experimental methods", "new mathematical models" based on phase equilibria data and equations of state (EOS), and available "published models". Experimental methods are time-consuming and costly. Moreover, they can handle only limited conditions. Mathematical models require availability of a considerable amount of reservoir fluid composition data, which may not be available most of the time. Although, the published models are simpler and faster to use, one must however recognise that most of these models were developed and validated based on limited data ranges from site-specific conditions. Therefore, their applications cannot be generic. Another noteworthy point is that most of the interactions models have been developed using dead oil data and pure CO₂ as an injected gas. Hence, they do not perform well for a wider range of live oils, as well as injected flue gases, which contain different components besides CO₂. Consequently, there is a need to have more reliable miscibility and interaction models, which can handle a much wider range of conditions and different data sources. Also, these models should be able to consider all the major variables, different injected gas compositions, and live oil in addition to dead oil. 3. GA-based Models Developed in This Research: -- GA-based model for more reliable prediction of minimum miscibility pressure (MMP) between reservoir oil and CO₂: This model recognised the major variables affecting MMP (reservoir temperature, MWc₅₊ , and volatiles and intermediates compositions). It has been successfully validated with published experimental data and compared to common models in the literature. It is noted that GA-based CO₂-oil MMP offered the best match with the lowest error and standard deviation. -- GA-based flue gas-oil MMP model: For this model, the MMP was regarded as a function of the injected gas solubility into oil, which in turn is related to the injected gas critical properties (pseudocritical temperature and pressure) besides reservoir temperature and oil composition. A critical temperature modification factor was also used in developing this model. The GA-based model has also been successfully validated against published experimental data and compared to several models in the literature. It yielded the best match with the lowest average error and standard deviation. Moreover, unlike other models, it can be used more reliably for gases with higher N₂ (up to 20 mole%) and different non-CO₂ components (e.g., H₂S, N₂, SOₓ, O₂, and C₁-C₄) with higher ratio (up to 78 mole%). -- GA-based CO₂-oil physical properties models: These models have been developed to predict CO₂ solubility, impact on the oil swelling factor, CO₂-oil density, and CO₂-oil viscosity for both dead and live oils. These models recognised the major variables that affect each physical property and also properly address the effects of CO2 liquefaction pressure and oil molecular weight (MW). These models have been successfully validated with published experimental data and have been compared against several widely used models. The GA-based CO₂-oil properties models yielded more accurate predictions with lower errors than other models that have been tested. Furthermore, unlike the other tested models, which are applicable to only limited data ranges and conditions, GA-based models can be applied over a wider data range and conditions. -- GA-based flue gas-oil physical properties models: These models predict flue gas-oil properties such as, flue gas solubility, impact on the oil swelling factor, and flue gas-oil density and viscosity while recognising all the major variables affecting each property. Also, the GA-based models recognised the different injected flue gas compositions. These models have been successfully validated with published experimental data and have also been compared against other commonly reported CO₂-oil models, which are often used for flue gas-oil physical properties prediction. The GA-based models consistently yielded a lower prediction error than the models that have been tested. Furthermore, unlike other models, which are applicable only over limited data ranges and conditions, GA-based models can be valid over a wider range of data under various conditions. All the above-mentioned models, developed in this research, are particularly useful when experimental data are lacking and the project financial situation is a concern. In addition, these models can be useful as a fast track gas flooding project screening guide. Also, they can easily be incorporated into a reservoir simulator for CO₂ or flue gas flooding design and simulation. Furthermore, they can serve as yet another useful tool to design optimal and economical experimental test protocols to etermine the miscibility and interactions between the injected CO₂ or flue gas and oils in gas flooding processes.http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1236741
Thesis (Ph.D.) -- University of Adelaide, Australian School of Petroleum, 2006.
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Trusler, J. P. Martin, Shane P. Cadogan, Geoffrey C. Maitland, and Catinca Secuianu. "Measurement and modelling of mass diffusion coefficients for application in carbon dioxide storage and enhanced oil recovery." 2019. https://ul.qucosa.de/id/qucosa%3A38064.
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In this work, measurements were carried out by the Taylor dispersion method [1, 2] to determine the
mutual diffusion coefficient for CO2 in water or hydrocarbon at effectively infinite dilution.
Measurements were carried out for CO2 in water, hexane, heptane, octane, decane, dodecane,
hexadecane, cyclohexane, squalane and toluene at temperatures between 298 K and 423 K with
pressures up to 69 MPa. Measurements of CO2 diffusivity in different brines were also carried out by
13C pulsed-field gradient NMR.
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Shafiei, Ali. "Mathematical and Statistical Investigation of Steamflooding in Naturally Fractured Carbonate Heavy Oil Reservoirs." Thesis, 2013. http://hdl.handle.net/10012/7429.
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A significant amount of Viscous Oil (e.g., heavy oil, extra heavy oil, and bitumen) is trapped in Naturally Fractured Carbonate Reservoirs also known as NFCRs. The word VO endowment in NFCRs is estimated at ~ 2 Trillion barrels mostly reported in Canada, the USA, Russia, and the Middle East. To date, contributions to the world daily oil production from this immense energy resource remains negligible mainly due to the lack of appropriate production technologies. Implementation of a VO production technology such as steam injection is expensive (high capital investment), time-consuming, and people-intensive. Hence, before selecting a production technology for detailed economic analysis, use of cursory or broad screening tools or guides is a convenient means of gaining a quick overview of the technical feasibility of the various possible production technologies applied to a particular reservoir. Technical screening tools are only available for the purpose of evaluation of the reservoir performance parameters in oil sands for various thermal VO exploitation technologies such as Steam Assisted Gravity Drainage (SAGD), Cyclic Steam Stimulation (CSS), Horizontal well Cyclic steam Stimulation (HCS), and so on. Nevertheless, such tools are not applicable for VO NFCRs assessment without considerable modifications due to the different nature of these two reservoir types (e.g., presence and effects of fracture network on reservoir behavior, wettability, lithology, fabric, pore structure, and so on) and also different mechanisms of energy and mass transport. Considering the lack of robust and rapid technical reservoir screening tools for the purpose of quick assessment and performance prediction for VO NFCRs under thermal stimulation (e.g., steamflooding), developing such fast and precise tools seems inevitable and desirable.
In this dissertation, an attempt was made to develop new screening tools for the purpose of reservoir performance prediction in VO NFCRs using all the field and laboratory available data on a particular thermal technology (vertical well steamflooding). Considering the complex and heterogeneous nature of the NFCRs, there is great uncertainty associated with the geological nature of the NFCRs such as fracture and porosity distribution in the reservoir which will affect any modeling tasks aiming at modeling of processes involved in thermal VO production from these types of technically difficult and economically unattractive reservoirs. Therefore, several modeling and analyses technqiues were used in order to understand the main parameters controlling the steamflooding process in NFCRs and also cope with the uncertainties associated with the nature of geologic, reservoir and fluid properties data. Thermal geomechanics effects are well-known in VO production from oil sands using thermal technologies such as SAGD and cyclic steam processes. Hence, possible impacts of thermal processes on VO NFCRs performance was studied despite the lack of adequate field data.
This dissertation makes the following contributions to the literature and the oil industry: Two new statistical correlations were developed, introduced, and examined which can be utilized for the purpose of estimation of Cumulative Steam to Oil Ratio (CSOR) and Recovery Factor (RF) as measures of process performance and technical viability during vertical well steamflooding in VO Naturally Fractured Carbonate Reservoirs (NFCRs). The proposed correlations include vital parameters such as in situ fluid and reservoir properties. The data used are taken from experimental studies and also field trials of vertical well steamflooding pilots in viscous oil NFCRs reported in the literature. The error percentage for the proposed correlations is < 10% for the worst case and contains fewer empirical constants compared with existing correlations for oil sands. The interactions between the parameters were also considered. The initial oil saturation and oil viscosity are the most important predictive factors. The proposed correlations successfully predicted steam/oil ratios and recovery factors in two heavy oil NFCRs. These correlations are reported for the first time in the literature for this type of VO reservoirs.
A 3-D mathematical model was developed, presented, and examined in this research work, investigating various parameters and mechanisms affecting VO recovery from NFCRs using vertical well steamflooding. The governing equations are written for the matrix and fractured medium, separately. Uncertainties associated with the shape factor for the communication between the matrix and fracture is eliminated through setting a continuity boundary condition at the interface. Using this boundary condition, the solution method employed differs from the most of the modeling simulations reported in the literature. A Newton-Raphson approach was also used for solving mass and energy balance equations. RF and CSOR were obtained as a function of steam injection rate and temperature and characteristics of the fractured media such as matrix size and permeability. The numerical solution clearly shows that fractures play an important role in better conduction of heat into the matrix part. It was also concluded that the matrix block size and total permeability are the most important parameters affecting the dependent variables involved in steamflooding.
A hybrid Artificial Neural Network model optimized by co-implementation of a Particle Swarm Optimization method (ANN-PSO) was developed, presented, and tested in this research work for the purpose of estimation of the CSOR and RF during vertical well steamflooding in VO NFCRs. The developed PSO-ANN model, conventional ANN models, and statistical correlations were examined using field data. Comparison of the predictions and field data implies superiority of the proposed PSO-ANN model with an absolute average error percentage < 6.5% , a determination coefficient (R2) > 0.98, and Mean Squared Error (MSE) < 0.06, a substantial improvement in comparison with conventional ANN model and empirical correlations for prediction of RF and CSOR. This indicates excellent potential for application of hybrid PSO-ANN models to screen VO NFCRs for steamflooding. This is the first time that the ANN technique has been applied for the purpose of performance prediction of steamflooding in VO NFCRs and also reported in the literature. The predictive PSO-ANN model and statistical correlations have strong potentials to be merged with heavy oil recovery modeling softwares available for thermal methods. This combination is expected to speed up their performance, reduce their uncertainty, and enhance their prediction and modeling capabilities.
An integrated geological-geophysical-geomechanical approach was designed, presented, and applied in the case of a NFCR for the purpose of fracture and in situ stresses characterization in NFCRs. The proposed methodology can be applied for fracture and in situ stresses characterization which is beneficial to various aspects of asset development such as well placement, drilling, production, thermal reservoir modeling incorporating geomechanics effects, technology assessment and so on. A conceptual study was also conducted on geomechanics effects in VO NFCRs during steamflooding which is not yet well understood and still requires further field, laboratory, and theoretical studies. This can be considered as a small step forward in this area identifying positive potential of such knowledge to the design of large scale thermal operations in VO NFCRs.
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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.
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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 2018The 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.
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Jarullah, Aysar Talib, Iqbal M. Mujtaba, and Alastair S. Wood. "Kinetic model development and simulation of simultaneous hydrodenitrogenation and hydrodemetallization of crude oil in trickle bed reactor." 2011. http://hdl.handle.net/10454/6032.
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One of the more difficult tasks in the petroleum refining industries that have not been considered largely in the literature is hydrotreating (HDT) of crude oil. The accurate calculations of kinetic models of the relevant reaction scheme are required for obtaining helpful models for HDT reactions, which can be confidently used for reactor design, operating and control. In this work, an optimization technique is employed to evaluate the best kinetic models of a trickle bed reactor (TBR) process utilized for hydrodenitrogenation (HDN) and hydrodemetallization (HDM) that includes hydrodevanadization (HDV) and hydrodenickelation (HDNi) of crude oil based on pilot plant experiments. The minimization of the sum of the squared errors (SSE) between the experimental and estimated concentrations of nitrogen (N), vanadium (V) and nickel (Ni) compounds in the products is used as an objective function in the optimization problem to determine the kinetic parameters.
A series of experimental work was conducted in a continuous flow isothermal trickle bed reactor, using crude oil as a feedstock and the commercial cobalt¿molybdenum on alumina (Co¿Mo/¿-Al2O3) as a catalyst.
A three-phase heterogeneous model based on two¿film theory is developed to describe the behaviour of crude oil hydroprocessing in a pilot¿plant trickle bed reactor (TBR) system. The hydroprocessing reactions have been modelled by power law kinetics with respect to nitrogen, vanadium and nickel compounds, and with respect to hydrogen. In this work, the gPROMS (general PROcess Modelling System) package has been used for modelling, simulation and parameter estimation via optimization. The model simulations results were found to agree well with the experiments carried out in a wide range of the studied operating conditions. The model is employed to predict the concentration profiles of hydrogen, nitrogen, vanadium and nickel along the catalyst bed length in three phases.
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Jarullah, Aysar Talib, Iqbal M. Mujtaba, and Alastair S. Wood. "Kinetic parameter estimation and simulation of trickle-bed reactor for hydrodesulfurization of crude oil." 2011. http://hdl.handle.net/10454/6031.
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