Etude expérimentale et numérique de la combustion in-situ d’huiles lourdes

Ce travail de thèse, réalisé en collaboration avec l’IMFT et TOTAL, traite de la modélisation de la combustion in-situ appliquée à une huile lourde Vénézuéliène. Il a été initié suite à une observation simple : même si le procédé est étudié depuis plusieurs décénies, on ne peut pas encore le modéliser correctement. Des résultats expérimentaux, issus d’expérience à l’échelle du laboratoire (tubes à combustions), ne sont pas reproductibles avec des outils numériques commerciaux de types simulateurs réservoirs thermiques. Par conséquent, et face à ce constat, nous avons été contraint d’explorer plusieurs pistes pour améliorer la modélisation du procédé : – La chimie et les méthodes de détermination de mécanismes réactionnels. – La description thermodynamique d’une huile lourde et le calcul d’équilibre triphasique. – Le transport de masse et de chaleur dans un milieu poreux, en situation multiphasique, réactive et miscible. – La conception d’un modèle mathématique et numérique d’un modèle complet. Nous pensons que le problème pluridisciplinaire et fortement complexe peut trouver une réponse si l’ensemble des mécanismes et leurs liens sont traités de façon adéquate. Une campagne expérimentale (expériences de cellules cinétiques), portant sur l’étude des effets de l’eau sur les réactions chimiques de l’huile, a permis de mettre en évidence des effets inattendus et nouveaux. Ces données, complétées par des expériences de types tubes à combustion, fournissent une importante base de données expérimentale. Pour modéliser les expériences de cellules cinétiques, nous avons tout d’abord développer un nouvel outil de simulation directe, reposant sur une description compositionnelle de l’huile où les comportements de toutes les phases sont prédits par les équations d’états. Le calcul d’équilibre est fait grâce à un flash diphasique. Afin de déterminer un mécanisme réactionnel paramétré, nous avons couplé ce dernier outil à un algorithme génétique. Finalement, dans le but de simuler les expériences de tubes à combustion, un nouveau simulateur compositionel, triphasique, thermique et réactif a été développé. Il est spécialement adapté à la simulation de ce genre d’expérience. Le calcul d’équilibre de phase est réalisé grâce à un nouvel outil développé pour l’occasion. Ce dernier repose sur l’hypothèse free water et repose sur une formulation originale et novatrice

Modelling of non-consolidated oil shale semi-coke forward combustion: influence of carbon and calcium carbonate contents

A one dimensional (1-D) numerical model to describe forward filtration combustion in a porous bed is proposed. The numerical model is based on mass and momentum conservation law (generalized Darcy’s law). We assume local thermal equilibrium between gas and solid phases. The effect of carbon and calcium carbonate content on the propagation of the high temperature combustion front has been investigated. A simple carbon oxidation reaction, producing CO and CO2, describes the combustion. We found that increasing the carbon content of the bed increases the peak temperature. However, the combustion front velocity versus carbon content does not show a monotone behaviour. The front velocity increases while carbon content increases up to a certain value and then decreases. Also, we observed that higher the temperature is, stronger the calcium carbonate decomposition is. Consequently, the calcium carbonate decomposition is closely linked to the peak temperature. Moreover, increasing the calcium carbonate content of the porous bed resulted a decrease of the peak temperature. These results as well as the composition of produced gases are consistent with the previous published experimental study. Results of this paper show that using a 1-D model with a simple reaction scheme for combustion and for calcium carbonate decomposition produces satisfactory results for simulation of filtration combustion process

Modelling In-situ Upgrading of Heavy Oil Using Operator Splitting Methods

Heavy oil and oil sands are important hydrocarbon resources that account for over 10 trillion barrels (Meyer et al., 2007), nearly three times the conventional oil in place in the world. There are huge, wellknown resources of heavy oil, extra-heavy oil, and bitumen in Canada, Venezuela, Russia, the USA and many other countries. The oil sands of Alberta alone contain over two trillion barrels of oil. In Canada, approximately 20% of oil production is from heavy oil and oil sand resources

Scaling heat and mass flow through porous media during pyrolysis.

The modelling of heat and mass flow through porous media in the presence of pyrolysis is complex because various physical and chemical phenomena need to be represented. In addition to the transport of heat by conduction and convection, and the change of properties with varying pressure and temperature, these processes involve transport of mass by convection, evaporation, condensation and pyrolysis chemical reactions. Examples of such processes include pyrolysis of wood, thermal decomposition of polymer composite and in situ upgrading of heavy oil and oil shale. The behaviours of these systems are difficult to predict as relatively small changes in the material composition can significantly change the thermophysical properties. Scaling reduces the number of parameters in the problem statement and quantifies the relative importance of the various dimensional parameters such as permeability, thermal conduction and reaction constants. This paper uses inspectional analysis to determine the minimum number of dimensionless scaling groups that describe the decomposition of a solid porous material into a gas in one dimension. Experimental design is then used to rank these scaling groups in terms of their importance in describing the outcome of two example processes: the thermal decomposition of heat shields formed from polymer composites and the in situ upgrading of heavy oils and oil shales. A sensitivity analysis is used to divide these groups into three sets (primary, secondary and insignificant), thus identifying the combinations of solid and fluid properties that have the most impact on the performance of the different processes

Modelling Heat and Mass Transfer in Porous Material during Pyrolysis using Operator Splitting and Dimensionless Analysis

Dimensionless analysis isused to improve the computational performance when using operator splitting methods to model the heat and mass transfer during pyrolysis. The specific examples investigated are thermal decomposition of polymer composite when used as heat shields during space-craft re-entry or for rocket nozzle’s protection, and the In-Situ Upgrading (ISU) of solid oil shale by subsurface pyrolysis to form liquid oil and gas. ISU is a very challenging process to model numerically because a large number of components need to be modelled using a system of equations that are both highly non-linear and strongly coupled. Inspectional Analysis is used to determine the minimum number of dimensionless groups that can be used to describe the process. This set of dimensionless numbers is then reduced to those that are key to describing the system behaviour. This is achieved byperforming a sensitivity study using Experimental Design torank the numbers in terms of their impact on system behaviour. The numbers are then sub-divided into those of primary importance, secondary importance and those which are insignificant based on the t-value of their effect, which is compared to the Bonferroni corrected t-limit and Lenth’s margin of error. Finally we use the sub-set of the most significant numbers to improve the stability and performance when numerically modelling this process. A range of operator splitting techniques is evaluated including the Sequential Split Operator (SSO), the Iterative Split Operator (ISO) and theAlternating Split Operator (ASO

Kinetics Oxidation of Heavy Oil. 2. Application of Genetic Algorithm for Evaluation of Kinetic Parameters

In-situ combustion (ISC) is the process of injecting air into oil reservoirs to oxidize part of the crude-oil and has been utilized for both light and heavy oil. The viscosity of the remaining crude-oil is reduced by the significant heat generated from combustion reactions, that contributes to enhanced oil recovery. In [give citation full out], we developed a new method to interpret Ramped Temperature Oxidation (RTO) experiments using a reactor model based on a compositional and full equation of state approach. In this work, we use this RTO reactor model coupled with an optimization tool in order to determine the optimal kinetic parameters for an extra heavy oil reservoir. Kinetic parameters are commonly determined using analytical methods and limited data. Typically only one type of observational data, for example oxygen consumption, is used from one experiment. Here, we use two series of experiments data, namely CO2 and O2 concentrations and a multi objective approach to obtain kinetic parameters for the different combustion reactions. We obtain finally a set of possible kinetic schemes, accouting for all mechanisms like reactions, phase changes and transport processes

Experimental and numerical study of heavy oil in-situ combustion

Ce travail de thèse, réalisé en collaboration avec l’IMFT et TOTAL, traite de la modélisation de la combustion in-situ appliquée à une huile lourde Vénézuéliène. Il a été initié suite à une observation simple : même si le procédé est étudié depuis plusieurs décénies, on ne peut pas encore le modéliser correctement. Des résultats expérimentaux, issus d’expérience à l’échelle du laboratoire (tubes à combustions), ne sont pas reproductibles avec des outils numériques commerciaux de types simulateurs réservoirs thermiques. Par conséquent, et face à ce constat, nous avons été contraint d’explorer plusieurs pistes pour améliorer la modélisation du procédé : – La chimie et les méthodes de détermination de mécanismes réactionnels. – La description thermodynamique d’une huile lourde et le calcul d’équilibre triphasique. – Le transport de masse et de chaleur dans un milieu poreux, en situation multiphasique, réactive et miscible. – La conception d’un modèle mathématique et numérique d’un modèle complet. Nous pensons que le problème pluridisciplinaire et fortement complexe peut trouver une réponse si l’ensemble des mécanismes et leurs liens sont traités de façon adéquate. Une campagne expérimentale (expériences de cellules cinétiques), portant sur l’étude des effets de l’eau sur les réactions chimiques de l’huile, a permis de mettre en évidence des effets inattendus et nouveaux. Ces données, complétées par des expériences de types tubes à combustion, fournissent une importante base de données expérimentale. Pour modéliser les expériences de cellules cinétiques, nous avons tout d’abord développer un nouvel outil de simulation directe, reposant sur une description compositionnelle de l’huile où les comportements de toutes les phases sont prédits par les équations d’états. Le calcul d’équilibre est fait grâce à un flash diphasique. Afin de déterminer un mécanisme réactionnel paramétré, nous avons couplé ce dernier outil à un algorithme génétique. Finalement, dans le but de simuler les expériences de tubes à combustion, un nouveau simulateur compositionel, triphasique, thermique et réactif a été développé. Il est spécialement adapté à la simulation de ce genre d’expérience. Le calcul d’équilibre de phase est réalisé grâce à un nouvel outil développé pour l’occasion. Ce dernier repose sur l’hypothèse free water et repose sur une formulation originale et novatrice.The study of this PhD, realized jointly with IMFT and TOTAL, deals with modeling of in-situ combustion applied to a Venezuelan heavy oil. It has begun with a relatively simple observation: even if the process has been extensively studied since some decades, we cannot correctly model it. Experiment data provided by lab scale experiments (combustion tubes) mismatches numerical results obtained from commercial thermal simulator, especially for wet experiments. The need to better understand the process related to this issue forced us to explore multiple tracks for various scientific fields. Thus, one can cite: • The chemistry and methods of reduction of reactive mechanisms. • The thermodynamic description of the heavy oil and the calculations of three-phase equilibrium. • Heat and mass transport in multiphase, reactive and miscible porous medium. • Mathematical and numerical design of a full model. The problem exceedingly complex can find a complete and consistent answer if one takes into account the whole mechanisms and links between them. We have followed this way in order to determine a robust reactive scheme using both theoretical numerical and experimental developments. A whole set of kinetic cell manipulations was conducted to better understand and discriminate the effects of water on chemistry on a certain type of heavy oils. New interactions and effects on steam on heavy oil combustion have been discovered and studied. These manipulations, supplemented by a set of some combustion tubes provide a large set of experimental data. This will compose our base case that we will try to match later using some new tools devised during this study. To model kinetic experiments, we firstly developed a new simulation tool based on a compositional description and a full equation of state formulation. Equilibrium calculation is made by a two-phase flash. To determine consistent kinetic parameters, we used a genetic algorithm coupled with the new tool. Finally, in order to validate the kinetic model and simulate combustion tube experiment, a new threephase compositional simulator has been developed. It is especially fitted to take into account characteristic of the experimental device. Three-phase equilibrium calculation is computed by a new free-wate

Etude expérimentale et numérique de la combustion in-situ d'huiles lourdes

TOULOUSE-INP (315552154) / SudocSudocFranceF

Scaling analysis of the In-Situ Upgrading of heavy oil and oil shale

International audienceThe In-Situ Upgrading (ISU) of heavy oil and oil shale is investigated. We develop a mathematical model for the process and identify the full set of dimensionless numbers describing the model. We demonstrate that for a model with nf fluid components (gas and oil), ns solid components and k chemical reactions, the model was represented by 9 + k x (3 + nf + ns - 2) + 8nf + 2ns dimensionless numbers. We calculated a range of values for each dimensionless numbers from a literature study. Then, we perform a sensitivity analysis using Design of Experiments (DOE) and Response Surface Methodology (RSM) to identify the primary parameters controlling the production time and energy efficiency of the process. The Damköhler numbers, quantifying the ratio of chemical reaction rate to heat conduction rate for each reaction, are found to be the most important parameters of the study. They depend mostly on the activation energy of the reactions and of the heaters temperature. The reduced reaction enthalpies are also important parameters and should be evaluated accurately. We show that for the two test cases considered in this paper, the Damköhler numbers needed to be at least 10 for the process to be efficient. We demonstrate the existence of an optimal heater temperature for the process and obtain a correlation that can be used to estimate it using the minimum of the Damköhler numbers of all reactions