An Experimental and Modeling Study of Carbon Dioxide/Bitumen and C4/Bitumen Phase Behavior at Elevated Temperatures Using Cold Lake Bitumen

SPE Journal ◽  
2018 ◽  
Vol 23 (06) ◽  
pp. 1991-2014 ◽  
Author(s):  
Sara Eghbali ◽  
Hassan Dehghanpour
Keyword(s):  
Carbon Dioxide ◽  
Phase Behavior ◽  
Gaseous Phase ◽  
Operating Pressure ◽  
Two Phase ◽  
Temperature Range ◽  
Similar Temperature ◽  
Bitumen Recovery ◽  
Equilibrium Calculations ◽  
Modeling Study

Summary The coinjection of carbon dioxide (CO2) or light hydrocarbons with steam in the steam-assisted-gravity-drainage (SAGD) process might enhance bitumen mobility and reduce the steam/oil ratio (SOR). Understanding and modeling the phase behavior of solvent/bitumen systems are essential for the development of in-situ processes for bitumen recovery. In this paper, an experimental and modeling study is undertaken to characterize the phase behavior of bitumen/CO2 and bitumen/C4 systems. Produced and dewatered oil from the Cenovus Osprey Pilot is used for the experiments. The Osprey Pilot produces oil from the Clearwater Formation. Constant-composition-expansion (CCE) experiments are conducted for characterizing Clearwater bitumen, CO2/bitumen mixture, and C4/bitumen mixture. The Peng and Robinson (1978) equation of state (EOS) (PR-EOS) is calibrated using the measured data and is used for pressure/volume/temperature (PVT) modeling. Multiphase equilibrium calculations are performed to predict the solubility of CO2 and C4 in the temperature range of 393.2 to 453.2 K. The potential of asphaltene precipitation for CO2/bitumen and C4/bitumen mixtures is also investigated using three screening criteria. According to the CCE tests and multiphase equilibrium calculations, C4 has much higher solubility in bitumen than does CO2 at operating pressure of 3997.9 kPa and temperature between 393.2 and 453.2 K (393.2 K < T < 453.2 K). During the CCE tests, coexistence of three equilibrium phases is observed for the C4/bitumen system with high C4 concentration. The three phases consist of a heavy oleic phase (L1), gaseous phase (V), and a light (solvent-rich) oleic phase (L2). Compositional analysis of the samples from L1 and L2 phases shows that C4 can extract light hydrocarbon components from bitumen into the L2 phase and preserve the heavy components in the L1 phase. Also, the L2 phase becomes darker by increasing the pressure, suggesting the extraction of heavier hydrocarbon components at higher pressures. Similar tests on the CO2/bitumen system show only two effective phases over a similar temperature range. The two phases consist of a heavy oleic phase (L1) and a gaseous phase (V). Phase-equilibrium regions are predicted using the regressed EOS model in the compositional space for the solvent/bitumen system. EOS predictions indicate two types of two-phase regions in the composition space for the C4/bitumen system (i.e., L1/L2 when 393.2 K < T < 421.2 K and L1/V when 421.2 K < T < 453.2 K). However, only one type of two-phase region (i.e., L1/V) exists in a similar temperature range for a CO2/bitumen system. The EOS predictions show that 1.8 wt% CO2 can reduce bitumen viscosity by up to 1.4 times, and 16.3 wt% C4 can reduce bitumen viscosity by up to 20 times when 393.2 K < T < 453.2 K. Viscosity calculations indicate that oil dilution by CO2 and C4 dissolution is more effective at lower temperatures, especially for C4. This shows the potential of injecting hot hydrocarbon solvents for bitumen recovery. The results show that asphaltene might precipitate in a system of C4/bitumen with high C4 concentration.

Effect of Common Impurities on the Phase Behavior of Carbon-Dioxide-Rich Systems: Minimizing the Risk of Hydrate Formation and Two-Phase Flow

SPE Journal ◽  
2011 ◽  
Vol 16 (04) ◽  
pp. 921-930 ◽  
Author(s):  
Antonin Chapoy ◽  
Rod Burgass ◽  
Bahman Tohidi ◽  
J. Michael Austell ◽  
Charles Eickhoff
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Phase Behavior ◽  
Water Content ◽  
Thermodynamic Model ◽  
Two Phase Flow ◽  
Hydrate Formation ◽  
Experimental Methodology ◽  
Phase Flow ◽  
Two Phase

Summary Carbon dioxide (CO2) produced by carbon-capture processes is generally not pure and can contain impurities such as N2, H2, CO, H2 S, and water. The presence of these impurities could lead to challenging flow-assurance issues. The presence of water may result in ice or gas-hydrate formation and cause blockage. Reducing the water content is commonly required to reduce the potential for corrosion, but, for an offshore pipeline system, it is also used as a means of preventing gas-hydrate problems; however, there is little information on the dehydration requirements. Furthermore, the gaseous CO2-rich stream is generally compressed to be transported as liquid or dense-phase in order to avoid two-phase flow and increase in the density of the system. The presence of impurities will also change the system's bubblepoint pressure, hence affecting the compression requirement. The aim of this study is to evaluate the risk of hydrate formation in a CO2-rich stream and to study the phase behavior of CO2 in the presence of common impurities. An experimental methodology was developed for measuring water content in a CO2-rich phase in equilibrium with hydrates. The water content in equilibrium with hydrates at simulated pipeline conditions (e.g., 4°C and up to 190 bar) as well as after simulated choke conditions (e.g., at -2°C and approximately 50 bar) was measured for pure CO2 and a mixture of 2 mol% H2 and 98 mol% CO2. Bubblepoint measurements were also taken for this binary mixture for temperatures ranging from -20 to 25°C. A thermodynamic approach was employed to model the phase equilibria. The experimental data available in the literature on gas solubility in water in binary systems were used in tuning the binary interaction parameters (BIPs). The thermodynamic model was used to predict the phase behavior and the hydrate-dissociation conditions of various CO2-rich streams in the presence of free water and various levels of dehydration (250 and 500 ppm). The results are in good agreement with the available experimental data. The developed experimental methodology and thermodynamic model could provide the necessary data in determining the required dehydration level for CO2-rich systems, as well as minimum pipeline pressure required to avoid two-phase flow, hydrates, and water condensation.

scholarly journals Experimental and Modeling Study of the Phase Behavior of (Heptane + Carbon Dioxide + Water) Mixtures

2015 ◽  
Vol 60 (12) ◽  
pp. 3670-3681 ◽  
Author(s):  
Saif. Z. S. Al Ghafri ◽  
Esther Forte ◽  
Amparo Galindo ◽  
Geoffrey C. Maitland ◽  
J. P. Martin Trusler
Keyword(s):  
Carbon Dioxide ◽  
Phase Behavior ◽  
Modeling Study

Equilibrium Calculations for Coexisting Liquid Phases

1984 ◽  
Vol 24 (01) ◽  
pp. 87-96 ◽  
Author(s):  
Rasmus Risnes
Keyword(s):  
Phase Behavior ◽  
Fluid Phase ◽  
Second Order ◽  
Phase Boundaries ◽  
Two Phase ◽  
Modeling Tools ◽  
Hydrocarbon Liquid ◽  
Liquid Phases ◽  
Miscible Flooding ◽  
Equilibrium Calculations

Abstract Modeling of reservoir processes like gas miscible flooding may require consideration of phase equilibrium between multiple liquid phases. Under certain conditions two hydrocarbon liquid phases may form; one may also want to account for mass transfer between the hydrocarbon and the aqueous phases. This paper describes a refined successive substitution (SS) method for calculating multiphase flash equilibrium. The phase behavior procedure proceeds in a stepwise manner, and additional phases are introduced by a special testing scheme based on phase fugacities. This is to avoid trivial solutions and to ensure continuity across phase boundaries. The method has been tested on various three- and four-phase systems, and examples of application show that the method performs well. Introduction Fluid phase behavior constitutes a very important aspect of more sophisticated oil recovery processes such as gas miscue flooding. In such processes mixtures of the reservoir fluids and the injected gas typically may approach critical conditions, and laboratory experiments have shown that the oil phase may in some cases split into two or more coexisting hydrocarbon liquid phases. In addition, interaction with the water phase may become important as the dissolution of gas components in water may affect the overall process performance significantly. The complexity of phase behavior during gas miscible flooding makes modeling and predictions a demanding task. Cubic Redlich-Kwong type EOS's have proved applicable for both gaseous and liquid phases. Thus, because of their simplicity, their reasonable accuracy, and their consistency near critical points, they have received much recent attention as a tool for describing compositional hydrocarbon reservoir phenomena. Various schemes for flash equilibrium calculations based on an EOS have been proposed. Broadly, they may be categorized as variants of the widely applied SS method or as second-order Newton-type methods. Most applications deal with two-phase problems, but extensions to multiphase problems have been reported. A basic solution scheme for multiphase cases was presented by Peng and Robinson. In addition, an extension of the minimum variable Newton technique was described by Fussell, and a combination of both first- and second-order methods was considered by Mehra and Mehra et al. One main problem with flash equilibrium calculations band on EOS's convergence toward trivial solutions and a proper delineation of phase boundaries. This is so for two-phase problems but even more so for multiphase problems, where phase boundaries may be very close to each other and good estimates of equilibrium K-values are more difficult to obtain. The work described here is part of a research project aimed at development of numerical modeling tools for EOR processes. The method for multiphase equilibrium calculations presented is an extension of the refined SS method previously developed for two-phase problems. The method has been incorporated into a fluid phase behavior package (COPEC). In developing the method, special emphasis has been put on computational efficiency and continuity across phase boundaries. Calculation Steps of Multiphase Flash The basis for our approach to the multiphase flash equilibrium problem is the SS method, which consists of the following steps.1. Assume equilibrium K-values.2. Calculate the phase distribution and compositions corresponding to the given K-values.3. Calculate component fugacities in each phase and check forequality.4. If equality is not achieved. correct the K-values on the basis of the fugacities and repeat from Step 2. We assume that fugacities are given from a cubic EOS (Redlich-Kwong, Peng-Robinson), but the problem of selecting suitable parameters, especially for lumped and/or heavy components, is considered beyond the scope of this paper. If the initial K-value estimates are sufficient, simultaneous handling of mi phases is probably the most efficient method. Frequently this is not the case, however, and the method then easily, becomes unstable and leads to trivial solutions. We have found it advantageous, therefore, to develop a more stepwise approach. Existence of the different phases is tested explicitly, and the sets of equilibrium constants are developed phase by phase before all phases are handled simultaneously. SPEJ P. 87^

Four-Phase Equilibrium Calculations of Carbon Dioxide/Hydrocarbon/Water Systems With a Reduced Method

SPE Journal ◽  
2013 ◽  
Vol 18 (05) ◽  
pp. 943-951 ◽  
Author(s):  
Saeedeh Mohebbinia ◽  
Kamy Sepehrnoori ◽  
Russell T. Johns
Keyword(s):  
Carbon Dioxide ◽  
Phase Equilibrium ◽  
Phase Behavior ◽  
Water Systems ◽  
Computational Time ◽  
General Strategy ◽  
Recovery Processes ◽  
Carbon Dioxide Co2 ◽  
Almost All ◽  
Equilibrium Calculations

Summary Three hydrocarbon phases can coexist at equilibrium at relatively low temperatures in many carbon dioxide (CO2) floods. The formation of an aqueous phase in contact with hydrocarbon phases is inevitable in almost all recovery processes, because of the permanent presence of water in the reservoirs either as injection fluid or as initial formation water. As the number of phases increases, flash calculations become more difficult and time-consuming. A possible approach to reduce the computational time of the phase-equilibrium calculations is to use reduced methods. This paper presents a general strategy to model the phase behavior of CO2/ hydrocarbon/water systems in which four equilibrium phases occur by use of a reduced-flash approach. The speedup obtained by a reduced-flash algorithm compared with the conventional-flash approach is demonstrated for a different number of components and phases. The results show a significant speedup in the Jacobian-matrix construction and in Newton-Raphson (NR) iterations by use of the reduced method when four phases are present. The computational advantage of the reduced method increases rapidly with the number of phases and components. The developed four-phase reduced-flash algorithm is used to investigate the effect of introducing water on the phase behavior of two west Texas oil/CO2 mixtures. The results show changes in the phase splits and saturation pressures by adding water to these CO2/hydrocarbon systems.

Solution Properties and Phase Behavior of Ammonium Hexylene Octyl Succinate in Water and Water-Oil System

1970 ◽  
Vol 3 (1) ◽  
Author(s):  
Md. Hamidul Kabir ◽  
Ravshan Makhkamov ◽  
Shaila Kabir
Keyword(s):  
Critical Micelle Concentration ◽  
Phase Behavior ◽  
Liquid Crystalline ◽  
Carbon Number ◽  
Phase Region ◽  
Solution Properties ◽  
Middle Phase ◽  
Two Phase ◽  
Lamellar Liquid Crystal ◽  
Drug Ingredient

The solution properties and phase behavior of ammonium hexylene octyl succinate (HOS) was investigated in water and water-oil system. The critical micelle concentration (CMC) of HOS is lower than that of anionic surfactants having same carbon number in the lipophilic part. The phase diagrams of a water/ HOS system and water/ HOS/ C10EO8/ dodecane system were also constructed. Above critical micelle concentration, the surfactant forms a normal micellar solution (Wm) at a low surfactant concentration whereas a lamellar liquid crystalline phase (La) dominates over a wide region through the formation of a two-phase region (La+W) in the binary system. The lamellar phase is arranged in the form of a biocompatible vesicle which is very significant for the drug delivery system. The surfactant tends to be hydrophilic when it is mixed with C10EO8 and a middle-phase microemulsion (D) is appeared in the water-surfactant-dodecane system where both the water and oil soluble drug ingredient can be incorporated in the form of a dispersion. Hence, mixing can tune the hydrophile-lipophile properties of the surfactant. Key words: Ammonium hexylene octyl succinate, mixed surfactant, lamellar liquid crystal, middle-phase microemulsion. Dhaka Univ. J. Pharm. Sci. Vol.3(1-2) 2004 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

Theoretical Post-Dryout Heat Transfer Model

2018 ◽  
Vol 1 (1) ◽  
pp. 142-150
Author(s):  
Murat Tunc ◽  
Ayse Nur Esen ◽  
Doruk Sen ◽  
Ahmet Karakas
Keyword(s):  
Heat Transfer ◽  
Droplet Diameter ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Operating Pressure ◽  
Vertical Pipe ◽  
Two Phase ◽  
Experimental Values ◽  
Reactor Operating ◽  
Coolant System

A theoretical post-dryout heat transfer model is developed for two-phase dispersed flow, one-dimensional vertical pipe in a post-CHF regime. Because of the presence of average droplet diameter lower bound in a two-phase sparse flow. Droplet diameter is also calculated. Obtained results are compared with experimental values. Experimental data is used two-phase flow steam-water in VVER-1200, reactor coolant system, reactor operating pressure is 16.2 MPa. On heater rod surface, dryout was detected as a result of jumping increase of the heater rod surface temperature. Results obtained display lower droplet dimensions than the experimentally obtained values.

Dynamic Viscosity of Compressed Water to 10 Kilobar and Steam to 1500°C

1969 ◽  
Vol 11 (2) ◽  
pp. 189-205 ◽  
Author(s):  
E. A. Bruges ◽  
M. R. Gibson
Keyword(s):  
Gaseous Phase ◽  
Dynamic Viscosity ◽  
Low Temperatures ◽  
Pressure Range ◽  
Low Pressure ◽  
Temperature Range ◽  
Inversion Temperature ◽  
Pressure Steam ◽  
Correlating Equations ◽  
First Time

Equations specifying the dynamic viscosity of compressed water and steam are presented. In the temperature range 0-100cC the location of the inversion locus (mu) is defined for the first time with some precision. The low pressure steam results are re-correlated and a higher inversion temperature is indicated than that previously accepted. From 100 to 600°C values of viscosity are derived up to 3·5 kilobar and between 600 and 1500°C up to 1 kilobar. All the original observations in the gaseous phase have been corrected to a consistent set of densities and deviation plots for all the new correlations are given. Although the equations give values within the tolerances of the International Skeleton Table it is clear that the range and tolerances of the latter could with some advantage be revised to give twice the existing temperature range and over 10 times the existing pressure range at low temperatures. A list of the observations used and their deviations from the correlating equations is available as a separate publication.

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