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Agrawal P.,University of Calgary | Schoeggl F.F.,University of Calgary | Satyro M.A.,Virtual Materials Group | Taylor S.D.,Schlumberger | Yarranton H.W.,University of Calgary
Fluid Phase Equilibria | Year: 2012

The design of solvent-based and solvent assisted heavy oil recovery processes requires accurate predictions of phase behavior as straightforward as saturation pressures and as potentially complex as vapour-liquid-liquid equilibria and asphaltene precipitation. It is a challenge to predict this variety of phase behavior from a single fluid model. In this study, saturation pressures of dead and live Peace River bitumen were measured in a Jefri PVT cell at different concentrations of a multi-component solvent at temperatures from 20 to 180 °C. Saturation pressures and the onset of asphaltene precipitation were also measured for the bitumen diluted with n-pentane. The onset of precipitation was determined by titrating the bitumen with pentane and periodically circulating the mixture past a high pressure microscope. Literature data including saturation pressures and liquid-liquid phase boundaries for pseudo-binaries of bitumen and carbon dioxide, methane, ethane, and propane were also evaluated. The data were modeled with the Advanced Peng-Robinson Equation-of-State (APR EoS). The maltene fraction of the bitumen was characterized into pseudo-components based on extrapolated distillation data. The asphaltenes were characterized based on a Gamma distribution of the molecular weights of self-associated asphaltenes. The APR EoS was tuned to fit the saturation pressure and asphaltene onset data of the pseudo-binaries by adjusting the binary interaction parameter between the solvent and the bitumen pseudo-components. A temperature dependent binary interaction parameter correlation was developed for the interaction parameters. The model fit the saturation pressures and onset of asphaltene precipitation over a wide range of temperatures. The model predicted liquid-liquid boundaries as well as the saturation pressures of live oil and live oil diluted with condensate solvent, generally within experimental error. The model also predicted the asphaltene onset in propane diluted bitumen. © 2012 Elsevier B.V.


Motahhari H.,University of Calgary | Satyro M.A.,Virtual Materials Group | Taylor S.D.,Schlumberger | Yarranton H.W.,University of Calgary
Energy and Fuels | Year: 2013

The Expanded Fluid (EF) viscosity model for Newtonian fluids is extended to crude oils characterized as mixtures of defined components and pseudo-components. The EF models take the fluid density, dilute gas viscosity, pressure, and fluid composition as inputs and requires three fluid-specific parameters, c2, c3, and ρso, for the fluid or its components. Generally, experimental viscosity data are required to determine these values for each component. In this study, an internally consistent estimation method was developed to predict the fluid-specific parameters of the model for hydrocarbons when no experimental viscosity data are available. The method uses n-paraffins as the reference system and correlates the fluid-specific parameters for hydrocarbons as departures from the reference system. The method was evaluated against viscosity data of over 250 pure hydrocarbon compounds and petroleum distillation cuts. The model predictions were within the same order of magnitude of the measurements, with an overall average absolute relative deviation of 31%. The method was then used to calculate the correlation parameters for the pseudo-components of nine dead and live oils characterized on the basis of their gas chromatography (GC) assays. The viscosities of the crude oils were predicted within a factor of 3 of the measured values using the measured density of the oils as the input. The applicability of the EF model was also demonstrated using the densities determined with the Peng-Robinson equation of state. A simple method was proposed to tune the model to available viscosity data using a single multiplier to the c2 parameter (and also to c3 and ρs o if necessary) of the pseudo-components. Single-parameter tuning of the model improved the viscosity prediction for the characterized oils to within 30% of the measured values. © 2013 American Chemical Society.


Agrawal P.,University of Calgary | Schoeggl F.F.,University of Calgary | Satyro M.A.,Virtual Materials Group | Yarranton H.W.,University of Calgary
Society of Petroleum Engineers - Canadian Unconventional Resources Conference 2011, CURC 2011 | Year: 2011

The design of solvent-based and solvent assisted heavy oil recovery processes requires accurate predictions of phase behavior as straightforward as saturation pressures and as potentially complex as vapour-liquid-liquid equilibria and asphaltene precipitation. In this case study, saturation pressures of dead and live bitumen were measured in a Jefri PVT cell at different concentrations of a multi-component solvent at temperatures from 20 to 180 °C. Saturation pressures and the onset of asphaltene precipitation were also measured for the bitumen diluted with n-pentane. The onset of precipitation was determined by titrating the bitumen with pentane and periodically circulating the mixture past a high pressure microscope. The data were modeled with the Advanced Peng-Robinson equation of state (APR EoS). The maltene fraction of the bitumen was characterized into pseudo-components based on extrapolated distillation data. The asphaltenes were characterized based on a Gamma distribution of the molecular weights of self-associated asphaltenes. The APR EoS was tuned to match the saturation pressures by adjusting the binary interaction parameter between the solvent and the pseudo-components via a correlation based on critical temperatures. Rather than adjusting the interaction parameters for each pair of components, only the exponent in the correlation was adjusted. The role of mixing rules in correctly predicting the onset and amount of asphaltene precipitation is discussed. Copyright 2011, Society of Petroleum Engineers.


Ortiz D.P.,University of Calgary | Satyro M.A.,Virtual Materials Group | Yarranton H.W.,University of Calgary
Fluid Phase Equilibria | Year: 2013

A straightforward method is proposed to determine interactions parameters for phase equilibrium models based on a relatively small amount of distillation data. The data are collected using the advanced distillation curve method developed by Bruno [1,2] where boiling points are measured at true thermodynamic state points. The data are modeled using the trajectory optimization method developed by Satyro and Yarranton [3].The approach was tested on water/alcohol and gasoline/alcohol mixtures. Each mixture was distilled at atmospheric pressure. For the water/alcohol mixtures, the NRTL model was tuned to fit atmospheric distillation data by adjusting the interaction parameters (interaction energies and non-randomness factor). For the gasoline/alcohol mixtures, the gasoline was characterized from a GC hydrocarbon analysis and the advanced Peng-Robinson equation of state was tuned to atmospheric distillation data by adjusting the interaction parameters between the gasoline pseudo-components and the alcohols. The models, tuned only to distillation data, correctly predicted the phase behavior of these non-ideal mixtures including azeotropism. The model is entirely general and can be used to determine interaction parameters for activity coefficient or equation of state based models. © 2012 Elsevier B.V.


Diaz O.C.,University of Calgary | Schoeggl F.,University of Calgary | Yarranton H.W.,University of Calgary | Satyro M.A.,Virtual Materials Group
Fluid Phase Equilibria | Year: 2015

The vapor pressure and liquid heat capacity of seven biodiesel fuels and its components (fatty acid methyl esters - FAMEs) were modeled using the advanced Peng-Robinson equation of state. The dataset used for the modeling was obtained from the literature and included FAME properties and the composition, vapor pressure, and liquid heat capacity of the biodiesel fuels from different sources at temperatures from 50 to 130. °C and -30 to 75. °C, respectively. New values for the critical properties and acentric factor of FAMEs are introduced as well as new models for the ideal gas heat capacity for the FAMEs. The average AARD is 12% for vapor pressure and 3% for liquid heat capacity. © 2015 Elsevier B.V.


Satyro M.A.,Virtual Materials Group | Satyro M.A.,University of Calgary | Van Der Lee J.H.,Virtual Materials Group | Jacobs G.,Virtual Materials Group
GPA Annual Convention Proceedings | Year: 2010

Amine sweetening saturates gas stream with water. Saturated water content vary greatly with temperature pressure and composition, CO 2 and H 2S can greatly increase the equilibrium water content and nature of problem. Accurate prediction of saturated water content over the wide ranges of temperatures, pressures and compositions is key in being able identify potential problems, designing processes to avoid problems and explore opportunities. A discussion covers the existing water content data for sweet gases; new model framework that can accurately predict saturated water content in sweet gases; and flexibility of this model framework in water contents in acid gases and TEG dehydration system properties. This is an abstract of a paper presented at the 89th Annual Convention of the Gas Processors Association (Austin, TX 3/21-24/2010).


Motahhari H.,University of Calgary | Schoeggl F.F.,University of Calgary | Satyro M.A.,Virtual Materials Group | Yarranton H.W.,University of Calgary
Journal of Canadian Petroleum Technology | Year: 2013

Accurate predictions of heavy-oil and bitumen viscosity as a function of temperature, pressure, and composition are required for the design of thermal and solvent-based recovery methods. In this case study, the applicability of the recently developed Expanded Fluid (EF) viscosity model is tested on measured viscosities of diluted dead and live heavy oil and bitumen at temperatures from 20 to 175°C and pressures up to 10 MPa. Density and viscosity data were collected for a condensate solvent, dead (gas-free) bitumen, and dead heavy oil from western Canada, and for the corresponding live oils and diluted mixtures of the dead and live oils with condensate solvent. Solubility, density, and viscosity data for heavy oil saturated with carbon dioxide (CO2) were obtained from the literature. The model was fitted to the data of the dead oils and the condensate with average relative deviations less than 11%. The viscosity of the live bitumen and heavy oil was then predicted to within 21 and 31% of the measured value on the basis of measured and calculated live-oil densities, respectively. Diluting the live and dead bitumen with 3 to 30 wt% condensate or carbon dioxide reduced the viscosity by one to three orders of magnitude, and the viscosities were predicted with an average relative deviation less than 16 and 24% on the basis of measured and calculated mixture densities, respectively. Copyright © 2013 Society of Petroleum Engineers.


Loria H.,Virtual Materials Group | Motahhari H.,University of Calgary | Satyro M.A.,Virtual Materials Group | Yarranton H.W.,University of Calgary
Chemical Engineering Research and Design | Year: 2014

The expanded fluid (EF) viscosity model was implemented and further developed for efficient integration into a commercial process simulator (VMGSim™). The model has three adjustable parameters per component and its inputs are density, pressure and low pressure gas viscosity. The model was adapted to use densities determined by the Rackett correlation (liquid phase) and the Advanced Peng-Robinson Equation of State (vapor phase). The enhanced EF model fit experimental viscosities of pure hydrocarbons, water and polar compounds important for the simulation of oil and natural gas systems with average absolute errors just above 5%. The implemented EF model was tested against experimental viscosity data that included hydrocarbon and aqueous mixtures with average absolutes errors of 0.7 and 6.2% respectively. Generalized expressions for the estimation interaction parameters of binary mixtures involving paraffins, naphthenes, aromatics, alcohols, glycols and water were obtained. The EF model was also applied to crude oil (bitumen) examples. The three key developments for the efficient implementation of the EF model in a commercial simulator were: (1) the appropriate selection of phase density models; (2) the automatic determination of model fluid specific parameters; and (3) the use of generalized mixing rules for the calculation of binary interaction parameters. © 2014 The Institution of Chemical Engineers.

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