Phase behaviour modelling of Athabasca bitumen for in situ combustion applications

Phase behaviour modelling of reservoir fluid is a fundamental step for reservoir simulation. Furthermore, as the complexity of the recovery process increases, the fluid model plays a more important role in the reliability of the simulation outputs. Although the in situ combustion enhanced oil recovery method (ISC) is one of the most complex recovery techniques available in the petroleum engineering literature, for most of the simulation jobs related to this elaborate process only simple and rudimentary fluid characterization layouts are considered. In this work, the principal fluid properties of Athabasca bitumen with regard to the ISC process are recognized, extracted from the literature, validated for consistency, and used for the development of an inclusive and accurate fluid model. Then the fluid model is fully developed while considering the ISC reaction kinetics so that the model has both accuracy, indispensable for phase behaviour modelling, and consistency, essential for the reactions definitions.     

Oxidation reaction kinetics of Athabasca bitumen

The oxidation reaction kinetics of bitumen from Athabasca oil sands have been investigated in a flow-through fixed bed reactor using gas mixtures of various compositions. The system was modelled as an isothermal integral plug-flow reactor. The oxidation of bitumen was found to be first order with respect to oxygen concentration. Two models were examined to describe the kinetics of bitumen oxidation. In the first, the Athabasca bitumen is considered to be a single reactant and the oxidation reaction a single irreversible reaction. The activation energy for the overall reaction was found to be 80 kJ mol^?1. This model is limited to calculating the overall conversion of oxygen. Because the fraction of oxygen reacting to form carbon monoxide and carbon dioxide increases with temperature, a more sophisticated model was proposed to take this into account. The second model assumes that the bitumen is a single reactant and that the oxidation of bitumen may be described by two simultaneous, parallel reactions, one producing oxygenated hydrocarbons and water, the other producing CO and CO₂. The activation energy for the first reaction was found to be 67 kJ mol^?1, and for the second, 145 kJ mol^?1. This more sophisticated model explains the result that at higher temperatures more oxygen is consumed in the oxidation of carbon, because this reaction has a higher activation energy than the reaction leading to the production of oxygenated hydrocarbons and water. This model can also predict the composition of the product gases at various reaction conditions.     

Simulation Study of a Novel Process Co‐Producing Synthesis Gas and Light Olefins

There are abundant resources of heavy hydrocarbons worldwide, and their utilization is becoming more widespread as time progresses. The present paper proposes a process that combines coke gasification and heavy hydrocarbon pyrolysis, producing synthesis gas and light olefins. Simulation studies on the process are carried out by using Aspen Plus. The results show that the temperature of the gasification‐pyrolysis can be controlled by changing the feed rate of O₂ and steam. In addition, the coke jam problem can be solved by increasing the gasification‐pyrolysis temperature or residence time. The maximum amount of light olefins can be acquired by controlling the gasification‐pyrolysis residence time. More than 37 wt % heavy hydrocarbons are changed to synthesis gas with more than 15 wt % changed to light olefins in the case studied.     

Investigation of hydrogen bonding by oxygen functions in Athabasca bitumen

A study has been made of the role played by the oxygen functions in hydrogen-bonding interactions which occur between the asphaltene and resin entities of Athabasca bitumen. The results show that hydrogen bonding occurs readily between these fractions and allows feasible representation of the manner by which the asphaltenes are peptized by the resins.     

Effect of low-temperature oxidation on the composition of Athabasca bitumen

The effect of low temperature oxidation on the composition of Athabasca bitumen was examined. Oxidation temperatures in the range 125–135 °C and extents of oxidation up to 100mg $\text{O}{}_2\text{g}$ bitumen were investigated. The aromatics concentration was observed to decline steadily and the concentration of asphaltenes to increase, during oxidation. The saturates were unaffected by low-temperature oxidation. The resins concentration displayed a strange behaviour, first dropping and then increasing to a maximum and again dropping as oxidation proceeded.     

A new kinetic model for pyrolysis of Athabasca bitumen

Pyrolysis of bitumen is a key contributor to gas production in in situ combustion and in situ gasification recovery processes, yet a detailed reaction scheme, that includes a breakdown of products into the most abundant gas components, that is simple enough to be used in detailed thermal‐reactive simulation models, does not exist. Here, we present a novel reaction scheme for pyrolysis of Athabasca bitumen that was developed and calibrated against four experimental data sets (65 data points) over a temperature range from 130 to 422°C. The new model was then verified by comparing its thermogravimetric behaviour against published literature. © 2012 Canadian Society for Chemical Engineering     

Separation and characterization of foulant material in coker gas oils from Athabasca bitumen

Gas oil streams from the upgrading of oilsands bitumen contain toluene insoluble, gummy, solid foulants that cause process problems by plugging hydrotreater feed filters and catalyst beds. From a process optimization standpoint, it is of considerable interest to determine the exact origin and nature of this material in order to design remedial measures. We selected coker heavy gas oil (KHGO) from bitumen upgrading as the primary test material for this work but also include samples from other parts of the process.Typically, solids content of gas oils are determined by a filtration method. For the KHGO sample used here, this approach yielded a value of 45 ppm. We also compared solids content using ultra- and low-speed centrifugation techniques. With toluene as the diluent, both of these centrifugation methods gave virtually the same toluene insolubles (TI) value, i.e. 24 and 23 ppm, respectively. For paraffinic diluents the measured TI contents ranged from about 50 to 200 ppm. Our results demonstrate that KHGO may contain significant amounts of TI not measured by conventional filtration.Characterization of gas oil TI from different sampling points in the bitumen upgrading circuit showed that it is a nitrogen and oxygen rich organic material, associated with minor amounts of inorganic elements representative of ash-forming iron minerals and alumino-silicate clay. The most likely source for this intractable toluene insoluble fraction appears to be a low molecular weight pyrrollic species present in heavy gas oil. Such compounds are easily oxidized to produce insoluble polymers that can interact with inorganic minerals and metals, producing gummy material capable of blinding filters.     

Thermodynamic Equilibrium Calculations for the Reforming of Coke Oven Gas with Gasification Gas

Thermodynamic analyses of the reforming of coke oven gas with gasification gas for syngas were investigated as a function of coke oven gas‐to‐gasification gas ratio (1–3), oxygen‐to‐methane ratio (0–1.56), pressure (25–35 bar) and temperature (700–1100 °C). Thermodynamic equilibrium results indicate that the operating temperature should be approximately 1100 °C and the oxygen‐to‐methane ratio should be approximately 0.39, where about 80 % CH₄ and CO₂ can be converted at 30 bar. Increasing the operating pressure shifts the equilibrium toward the reactants (CH₄ and CO₂); increasing the pressure from 25 to 35 bar decreases the conversion of CO₂ from 73.7 % to 67.8 %. The conversion ratio of CO₂ is less than that in the absence of O₂. For a constant feed gas composition (7 % O₂, 31 % gasification gas, and 62 % coke oven gas), a H₂/CO ratio of about 2 occurs at temperatures of 950 °C and above. Pressure effects on the H₂/CO ratio are negligible for temperatures greater than 750 °C. The steam produced has an effect on the hydrogen selectivity, but its mole fraction decreases with temperature; trace amounts of other secondary products are observed.     

Catalytic pyrolysis of Athabasca bitumen in H2 atmosphere using microwave irradiation

Microwave-assisted catalytic pyrolysis was carried out for upgrading of Athabasca bitumen. The bitumen can be heated to the desired target temperature (430 °C) for pyrolysis with silicon carbide (SiC), a heating element, in approximately 10 min under microwave irradiation. However, the pyrolysis with SiC only resulted in heavy and viscous liquid product having an API gravity of 17.14°. Addition of Nickel and Molybdenum nanoparticles as catalysts enhanced the pyrolysis performance in terms of liquid yield and quality. In the pyrolysis with Mo nanoparticles, the yield and the API gravity of the liquid product were 72.0 wt% and 20.98°, respectively. However, the separate existence of nanoparticles and SiC in the reactor and the recovery problem of nanoparticles, might limit their application in microwave-assisted pyrolysis. In order to prepare a composite with microwave susceptibility and catalytic activity in one body, transition metals were loaded on alumina coated SiC. When it is compared to the direct application of metal nanoparticles to the pyrolysis of bitumen, the NiMo/Al₂O₃/SiC catalyst showed enhanced catalytic performance. The API gravity and sulfur contents of the liquid products from the pyrolysis with NiMo/Al₂O₃/SiC were 22.42° and 2.84 wt%, respectively.     

Kinetics of pyrolysis and combustion of oil shale sample from thermogravimetric data

Thermogravimetric (TG) data of oil shale obtained at MI (Waste to Energy laboratory) were studied to evaluate the kinetic parameters for El-Lujjun oil shale samples. Different heating rates were employed simulating pyrolysis reaction using Nitrogen as purging gas up to ∼800 °C. The extent of char combustion was found out by relating TG data for pyrolysis and combustion with the ultimate analysis. Due to distinct behavior of oil shale during pyrolysis, TG curves were divided into three separate events: moisture release; devolatization; and evolution of fixed carbon/char, where for each event, kinetic parameters, based on Arrhenius theory, were calculated. Three methods were used and compared: integral method; direct Arrhenius plot method; and temperature integral approximation method. Results showed that integral method is closer to the experiment, while no relationship was observed between activation energy and the heating rate.     

Conversion of Biomass Based Slurry in an Entrained Flow Gasifier

A two‐step process, BIOLIQ, with pyrolysis and subsequent entrained flow gasification has been developed at the Forschungszentrum Karlsruhe to produce synfuel from biomass. Experiments in a 60 kW pilot‐scale atmospheric entrained flow gasifier allow quantitative evaluation of the combustion behavior of biomass‐based slurry, leading to a better understanding of the gasification process.     

Separation and characterization of bitumen from Athabasca oil sand

Separation and chemical analysis was investigated using bitumen samples from Athabasca oil sand in Alberta. Fractionation according to solubility and polarity has been used to separate bitumen into its fractions. The solvent de-asphaltening was performed by n-pentane solvent (solubility fractionation), and the polarity fractionation using Fuller’s earth allows maltene to separate into SARA components (saturates, aromatics, resins and asphaltenes). The SARA components are analyzed comprehensively using elemental analysis (EA), Fourier-transformed infrared (FTIR), ultraviolet-visible spectroscopy (UV-vis), high performance chromatography (HPLC) and thermogravimetric analysis (TGA). EA (C, H, N, S), heavy metals (Ni, V) concentrations, FT-IR and UV-vis tests provided the explanation of chemical composition. From IR spectra, maltene and saturates/aromatics (sat/aro) contained more aliphatic compounds than resin or asphaltene. Also, IR spectrum of sat/aro was similar to crude oil and VGO (vacuum gas oil). Different UV signal data clearly indicates the contribution of aromatic constituents in the fractions. Using optimized analysis conditions of HPLC, we successfully separated the peaks for bitumen and its fractions. The characteristic peak pattern of SARA (saturates, aromatics, resins, asphaltenes) fractions was observed, and also the peak pattern of sat/aro was similar to that of crude oil and VGO. However, TGA results revealed that thermal behavior for sat/aro was similar to that of crude oil but different from that of VGO. Also, from the comparison between decomposition temperature of TGA and boiling point, their correspondence was found.     

A new process for synthesis gas by co-gasifying coal and natural gas

Production of synthesis gas with coal and natural gas co-gasification is a new process based on coupling of methane steam-reforming and coal gasification. The process concept is discussed in this paper. Experiments are carried out in a laboratory fixed-bed gasifying reactor to investigate the effect of feedstock on composition, ratio of hydrogen to carbon monoxide, concentrations of hydrogen and carbon monoxide in the produced raw synthesis gas. Preliminary experimental results indicate that the effect of steam flow rate on component, ratio of hydrogen to carbon monoxide and concentrations of hydrogen and carbon monoxide of the raw synthesis gas is slight, while the effect of oxygen flow rate is pronounced. When the ratio of oxygen to methane in feedstock is below 1, the ratio of hydrogen to carbon monoxide is greater than 1 and the total concentration of hydrogen and carbon monoxide is above 90%. Comparison of experimental results with calculated results shows that the composition of raw synthesis gas is near equilibrium.     

Nanosized Composite Pt‐Ru Catalysts for Production of Modern Modified Fuels

A Pt‐Ru/2 % Ce/(θ+α)‐Al₂O₃ nanosized catalyst was developed for selective catalytic oxidation of CH₄ to synthesis gas. The process was carried out entirely with the formation of synthesis gas at high selectivity by H₂ and CO with H₂:CO = 2.0 ratio only at Pt:Ru = 2:1 or 1:1 atomic ratio and short contact time on Pt‐, Ru‐, and Pt‐Ru low‐percentage catalysts. Samples, which were reduced by H₂ at high temperature, presented a mixture of Pt‐, Ru‐, and Pt‐Ru nanosized particles, its alloy in the mixed catalysts. The correlation between experimental results and data of physicochemical research was established. The activity together with physicochemical properties and quantum chemical calculations for the developed low‐percentage Pt‐Ru catalysts was investigated.     

Kinetics of pyrolysis,combustion and gasification of three biomass fuels

The paper compares the microstructural properties and the intrinsic reactivity of pine seed shells, olive husk and wood chips upon pyrolysis, combustion and gasification (with CO₂ and H₂O). Such biomasses, all of interest in energy production, are quite different from one another in terms of O/C and H/C content, of porosimetric structure and of ash content.     

Methane Oxyforming for Synthesis Gas Production

This article is concerned with the reforming of methane to synthesis gas; a review of the steam reforming Rxn is presented, and the dry reforming and partial oxidation Rxns introduced. Collectively, these processes are known as “oxyforming.” A background to oxyforming, industrial practice, and some of the most important latest developments will be presented, along with a section on the uses of synthesis gas. The current understanding of the Rxn mechanisms for the three processes and the problem of deactivation by carbon deposition will be discussed in detail. Finally, the economics of synfuel production will be addressed and compared with the production of other fuels, and the future directions and outlook for oxyforming will be forwarded. This article should allow the reader to make comparisons between these three important industrial reactions.     

Methane Oxyforming for Synthesis Gas Production

This article is concerned with the reforming of methane to synthesis gas; a review of the steam reforming Rxn is presented, and the dry reforming and partial oxidation Rxns introduced. Collectively, these processes are known as “oxyforming.” A background to oxyforming, industrial practice, and some of the most important latest developments will be presented, along with a section on the uses of synthesis gas. The current understanding of the Rxn mechanisms for the three processes and the problem of deactivation by carbon deposition will be discussed in detail. Finally, the economics of synfuel production will be addressed and compared with the production of other fuels, and the future directions and outlook for oxyforming will be forwarded. This article should allow the reader to make comparisons between these three important industrial reactions.     

Gas turbine combustion performance test of hydrogen and carbon monoxide synthetic gas

The development of coal IGCC (Integrated Gasification Combined Cycle) technology has made it possible to exploit electricity generated from coal at a low cost. Furthermore, IGCC is a pre-requisite for the development of CCS (Carbon Capture and Storage) technology and hydrogen generated from coal. To achieve the need to reduce CO₂ emissions, Korea’s 300 MW IGCC RDD&D (Research Development, Demonstration and Dissemination) project was launched in December 2006 under the leadership of the Korea Electric Power Corporation (KEPCO), with the support of the Korea Ministry of Knowledge Economy.When a new fuel is adapted to a gas turbine (such as syngas for IGCC), it is necessary to study the gas turbine combustion characteristics of the fuel, because gas turbines are very sensitive to its physical and chemical properties. This experimental study was conducted by investigating the combustion performance of synthetic gas, which is composed chiefly of hydrogen and carbon monoxide. The results of a test on synthetic gas combustion performance were compared with the results of methane combustion, which is a major component of natural gas. The results of the combustion test of both gases were examined in terms of the turbine’s inlet temperature, combustion dynamics, emission characteristics, and flame structure.From the results of this experimental study, we were able to understand the combustion characteristics of synthetic gas and anticipate the problems when synthetic gas rather than natural gas is fuelled to a gas turbine.     

Mechanistic study of partial oxidation of methane to synthesis gas over supported rhodium and ruthenium catalysts using in situ time-resolved FTIR spectroscopy

In situ time-resolved FTIR spectroscopy was used to study the reaction mechanism of partial oxidation of methane to synthesis gas and the interaction of CH₄/O₂/He (2/1/45) gas mixture with adsorbed CO species over SiO₂ and γ-Al₂O₃ supported Rh and Ru catalysts at 500–600°C. It was found that CO is the primary product for the reaction of CH₄/O₂/He (2/1/45) gas mixture over H₂ reduced and working state Rh/SiO₂ catalyst. Direct oxidation of methane is the main pathway of synthesis gas formation over Rh/SiO₂ catalyst. CO₂ is the primary product for the reaction of CH₄/O₂/He (2/1/45) gas mixture over Ru/γ-Al₂O₃ and Ru/SiO₂ catalysts. The dominant reaction pathway of CO formation over Ru/γ-Al₂O₃ and Ru/SiO₂ catalysts is via the reforming reactions of CH₄ with CO₂ and H₂O. The effect of space velocity on the partial oxidation of methane over SiO₂ and γ-Al₂O₃ supported Rh and Ru catalysts is consistent with the above mechanisms. It is also found that consecutive oxidation of surface CO species is an important pathway of CO₂ formation during the partial oxidation of methane to synthesis gas over Rh/SiO₂ and Ru/γ-Al₂O₃ catalysts.     

Cracking of vacuum residue from Athabasca bitumen in a thin film

A novel apparatus for cracking experiments based on very rapid induction heating is described. Oil and catalyst is deposited in a thin film on a metal strip made from a Curie-point alloy and heated rapidly by induction in an induction furnace. The setup offers several advantages, such as rapid heating and quenching, precise control of reaction times and temperatures, and minimization of heat and mass transfer effects. The apparatus is used in a study of the catalytic activity of calcium-modified chabazite for heavy oil cracking. The catalyst was also tested in a conventional setup in cracking of hexadecane to verify its catalytic activity. A clear catalytic effect can be seen for the hexadecane cracking, but the effect is absent for thin film cracking of the vacuum residue.