Artigo Hosiberto

7/30/2019 Artigo Hosiberto

1/11

Experimental apparatus for phase behavior study of solventbitumen systems:

A critical review and design of a new apparatus

Mohammad Kariznovi, Hossein Nourozieh, Jalal Abedi

Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Canada

a r t i c l e i n f o

Article history:Received 3 June 2010

Received in revised form 10 October 2010

Accepted 13 October 2010

Available online 23 October 2010

Keywords:

Experimental apparatus

Phase behavior

Solvent

Bitumen

a b s t r a c t

A new apparatus for studying the phase behavior of heavy oil and bitumen with different solvents hasbeen tested. It has the capability of determining physical properties, such as density, viscosity, and

compositions, of individual phases over a broad range of temperatures and pressures. One of the unique

features of this apparatus is that the method of detecting presence of different phases is based on the

values of density and viscosity of the phases rather than visual observation. Thus, the applicability of this

apparatus is not restricted to fluids that are transparent to visible light. In addition, this apparatus allows

taking samples from each phase for further analysis. The other unique feature of the apparatus is that it is

designed for an expeditious thermodynamic equilibration using a rocking cell with a free-rolling ball

inside which allows the effective agitation. The success of this design relies upon coupling advanced

apparatus construction techniques with accurate density and viscosity measurement for phase detection.

The experimental apparatus was tested for vaporliquid, liquidliquid, and vaporliquidliquid

equilibrium systems; and, the results are in good agreement with data published in the literature.

2010 Elsevier Ltd. All rights reserved.

1. Introduction

World production of heavy and extra-heavy oils, such as

bitumen, has increased as the conventional light and medium

crudes declined. In-situ bitumen recovery from oilsand forma-

tions has become economically successful over the past two

decades in Canada. Inventions and developments of recovery

processes, such as steam assisted gravity drainage (SAGD) and

vapor extraction (VAPEX) have contributed to this success [13].

Numerous schemes to utilize solvent and heat have recently

been invented and patented, in which the compound effects of sol-

vents and heat on the bitumen viscosity would provide bitumen

production rates that could be equivalent or even higher than

those from the injection of steam or solvent alone [4,5]. However,

the fact is the lack of basic data and mechanistic knowledge rele-

vant to the solvent/heat-assisted-recovery processes. Even the

most fundamental experimental data, such as the solubility of

commonly used solvents in bitumen, are not available. The quanti-

tative effects of solvent on bitumen viscosity, density, and phase

behavior are also not well understood. Thus, to acquire basic

knowledge for designing and optimizing such processes, it is

crucial to find out the phase behavior of the bitumen/solvent

system and its physical properties, such as density, viscosity, and

composition of each phase.

This study reviews the experimental setups that have been used

for phase behavior study of bitumen/solvent systems. It is not the

intention to only review the experimental setups, but also high-

light their shortcomings and limitations. Table 1 summarized the

apparatus which used for phase behavior study of bitumen/solvent

system. The specifications, capabilities, and limitations of each

experimental setup are also provided. The application of the

apparatus listed in Table 1 will be described in more details in

Section 2.

Considering the shortcomings and limitations of apparatuses

that were used for bitumen/solvent phase behavior, it is essential

to prepare, design, and construct an experimental apparatus for

measuring vaporliquid, liquidliquid, and vaporliquidliquid

systems or even one containing a solid phase.

Most of the above-mentioned experimental apparatuses (Table

1) can be used only for vaporliquid system and do not have the

capability of measuring the mole or weight fraction of feeding flu-

ids. However, the experimental and modeling studies by Mehrotra

and Sverck [1216] and Sverck and Mehrotra [8,17] indicated that

there is the possibility of formation of two liquid phases under

certain conditions for bitumen/solvent system. For instance, they

observed that, for a Cold Lake bitumen/carbon dioxide system at

the lowest temperature (15 C) and high pressure, the solubility

does not significantly increase with increasing the pressure. In

addition, there is crossover in the solubility measurement for

0016-2361/$ - see front matter 2010 Elsevier Ltd. All rights reserved.doi:10.1016/j.fuel.2010.10.019

Corresponding author. Address: 2500 University Dr., NW, Calgary, Alberta,

Canada T2N 1N4. Tel.: +1 403 220 5594.

E-mail address: [email protected] (J. Abedi).

Fuel 90 (2011) 536546

Contents lists available at ScienceDirect

Fuel

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / f u e l
http://dx.doi.org/10.1016/j.fuel.2010.10.019mailto:[email protected]://dx.doi.org/10.1016/j.fuel.2010.10.019http://www.sciencedirect.com/science/journal/00162361http://www.elsevier.com/locate/fuelhttp://www.elsevier.com/locate/fuelhttp://www.sciencedirect.com/science/journal/00162361http://dx.doi.org/10.1016/j.fuel.2010.10.019mailto:[email protected]://dx.doi.org/10.1016/j.fuel.2010.10.019


2/11

two isotherms, which indicates that the measured solubility for

carbon dioxide at 26 C and 10.6 MPa is slightly higher than at

15 C and 10.7 MPa. The possibility of the formation of a second li-

quid is increased as a heavier solvent, such as propane and butane,

at a low temperature and high pressure, is used.

Recently, the modeling study by Kariznovi et al. [18] confirms

the possibility of a second liquid phase at a low temperature for

carbon dioxide and ethane/bitumen systems. Thus, experimental

data on phase behavior is required to determine the operating con-

ditions that cause the formation of two liquid phases. Identification

of the phases and measurement of their properties (viscosity and

density) at conditions that have more than two phases are impor-

tant for phase behavior study and evaluation of the performance of

recovery processes.

The main objective of this research is to propose an experimen-tal apparatus to overcome the shortcomings associated with the

apparatus used for bitumen/solvent phase behavior study. Thus,

the proposed apparatus has no limitation for number of phases

and has the capability of measuring the mole or weight fraction

of feeding fluids. It can handle temperatures (T) up to 200 C, which

is the maximum operating temperature for the density measuring

cell, and pressures (P) up to 40 MPa.

The experimental setup has been verified using different simple

binary and ternary systems. The validation of the apparatus has

been made by using data from the literature for three different

systems: vaporliquid, liquidliquid, and vaporliquidliquid

systems. The results for these systems had been compared with

published data; and, good agreement was obtained. In addition,

the phase behavior of bitumen/propane mixture for vaporliquidand liquidliquid equilibrium were considered to validate the

capability of the proposed apparatus for bitumen/solvent mixtures.

The solubility as well as the saturated phase properties such as,

density, viscosity, and volume of the phases, was presented.

Section 3 describes the experimental apparatus and quality control

tests that were conducted to validate the setup for phase behavior

study.

2. Literature background

The first attempt to measure the properties of heavy oil and

bitumen with solvents dates back to 1980 by Jacobs et al. [6]

who measured the viscosity of gas-saturated Athabasca bitumen.Concurrently, Robinson et al. [19] and Robinson and Sim [20]

conducted phase behavior experiments on Athabasca bitumen

saturated with carbon dioxide and ethane at high temperatures

(up to 150 C) and Cold Lake bitumen saturated with carbon diox-

ide, respectively.

In 1980, Jacobs et al. [6] used an experimental setup for measur-

ing the effect of dissolved gases on the viscosity of bitumen. The

experimental apparatus consisted of a gear pump, mixing cell,

and viscometer, as shown in Fig. 1. To conduct an experiment,

the mixing cell was charged with bitumen and then pressurized

with desirable gases. A gas cylinder was connected to the mixing

cell and kept the pressure constant during the experiment.

The entire experimental setup was placed inside an insulated,

electrically heated, uniform temperature air-bath. Bitumen with

dissolved gas was pumped through the recycle and circulation

lines. The recycle line took the bitumen to the top of the mixingcell. The density measuring cell and viscometer, which were in-

stalled on the circulation line, continuously measured the density

and viscosity of the liquid phase. The division of flow in the circu-

lation and recycle lines was controlled by means of a valve in the

circulation line. A hemispherical screen at the top of mixing cell,

which was designed to increase the contact surface between gas

and liquid, speeded up the mixing process. The bitumen was circu-

lated at a constant pressure and temperature, until no change in

the viscosity of the liquid phase was observed. A constant viscosity

for a considerable time indicated that liquid is saturated at the gi-

ven temperature and pressure. Jacobs et al. [6] measured the effect

of the dissolved gas (carbon dioxide, methane, and nitrogen) on the

viscosity of Athabasca bitumen.

In 1982, Mehrotra and Svrcek [1216] and Svrcek and Mehrotra[17] used the experimental setup of Jacobs et al. [6] to measure the

effect of temperature and pressure on the solubility of methane,

ethane, carbon monoxide, carbon dioxide, and nitrogen in four dif-

ferent Alberta bitumens (Athabasca, Cold Lake, Peace River, and

Wabasca). The experimental setup was used to establish the equi-

librium condition. To measure the solubility of gas in bitumen,

they flashed the liquid phase at atmospheric condition. Addition

to solubility, they measured the viscosity and density of the satu-

rated phase for temperatures and pressures up to 110 C and

10 MPa, respectively. Mehrotra and Sverck concluded that the Ja-

cobs et al. apparatus has the capability to operate in low tempera-

ture where bitumen has a viscosity in the order of one million

centipoises.

Fu et al. [7] designed an experimental apparatus for studyingthe vaporliquid equilibrium of carbon dioxide and nitrogen with

Table 1

Capabilities and specifications of different experimental apparatus.

Experimental setup Jacobs et al.

[6]

Fu et al.

[7]

Svrcek and Mehrotra

[8]

Sayegh et al.

[9]

Abedi et al.

[10]

Badamchi-Zadeh et al.

[11]

New Setup

Equilibrium

mechanism

Circulation Rocking Circulation Circulation Magnetic mixer Rocking &

ball

Visual observation U U

Operation T, C 150 120 140 452 200 200

P, MPa 13.8 10 13 28 69 40

PVT study VL U U U U U U U

LL U U U

VLL U U U

Measurement Solub ilit y U U U U U U

Density U U U U U U

Viscosity U U U U U

Volume U U U U

Capability Sampling L V, L L L U

S/B ratio U U U

Volume,

cm3 >1200 10175 100 900

M. Kariznovi et al./ Fuel 90 (2011) 536546 537


3/11

Athabasca bitumen at the Alberta Research Council in 1985. They

modified a Ruska rocking cell apparatus for conducting their exper-

iments. Fig. 2 illustrates a schematic diagram of the apparatus. It

consisted of a charging and discharging system, a rocking equili-

bration cell and a sampling and analysis system. The detailed

shape of the equilibration cell and rocking system are shown in

Figs. 3 and 4, respectively. The equilibration cell was placed in a

constant temperature bath and was driven by a motor. To run an

experiment, the bitumen and gas were charged to the equilibration

cell. Equilibrium was achieved by the rocking of the equilibrium

cell and agitation. The pressure was measured during the experi-

ment; and, when there was no pressure change, the system was

stabilized for at least two days to ensure that the equilibrium con-

dition has been reached. There was a piston inside the equilibrium

cell (Fig. 3): this feature provided the capability of measuring the

volume of liquid and vapor.

Fig. 1. Experimental setup designed by Jacobs et al. [6].

Fig. 2. Experimental setup designed by Fu et al. [7].

538 M. Kariznovi et al./ Fuel 90 (2011) 536546


4/11

Furthermore, it became possible to take a sample from both theliquid and vapor at equilibrium. During sampling, the Ruska pump

maintained a constant pressure by means of the piston. Liquid and

vapor samples could be collected for further analysis.The setup was

tested for a temperature and pressure of 150 C and 13.8 MPa,

respectively. This apparatus could not measure the density and vis-

cosity of saturated phase, but it could be used for vaporliquid

phase equilibrium.Fu et al.[21] ransame experiments for Cold Lake

bitumen with methane and ethane at the Alberta Research Council

in 1988.

In 1989, Svrcek and Mehrotra [8] designed a new apparatus for

measuring the solubility and viscosity and density of gas saturated

bitumen, and they conducted some experiments with Peace River

bitumen. The experimental apparatus, which is illustrated in

Fig. 5, consisted of a Haake Rotovisco RV2 viscometer, Anton PaarDP 2000 density measuring cell, Lewa diaphragm pump, and

mixing cell with some necessary instrumentation. The entire setup

was placed in a Blue M oven to control the temperature.

To run the experiment for specific temperature, bitumen was

charged into the mixing cell; and, gas was then introduced into

the cell. To measure the solubility, the pressure was increased

stepwise and the experiment started with the lowest experiment

pressure, and the gas was dissolved into the bitumen through re-

peated circulation. The pump drew bitumen from the bottom of

the mixing cell to either discharge it into the top of the mixing cell

for further circulation or to transfer it through the density measur-

ing cell and sampling cell. Bitumen flowed through the micro filter

of differential pressure (DP) cell, which monitored the pressuredrop across it. This feature provided the capability of detecting so-

lid formation. Any sharp increase in the pressure drop indicated

the formation of solid phase.

The viscosity of the liquid phase was measured during the

experiments, and the equilibrium condition was determined by

constant viscosity. When equilibrium was achieved, a liquid sam-

ple was taken for solubility measurement, and the system pressure

was increased for the next pressure step. This procedure was re-

peated up to a maximum pressure of 10 MPa.

Sayegh et al. [9] designed an experimental setup (Fig. 6) for

measuring the phase behavior and physical properties of heavy

oil/carbon dioxide mixtures and generated the data for Lindbergh

heavy oil. The experimental setup was used for saturating crude

oil with carbon dioxide and also the measurement of the saturatedphases composition, density, and viscosity. The apparatus

consisted of two cells with floating pistons. One of cells had two

windows for visual observation, and the other was a blind cell.

The two cells were connected by a gear pump for fluid circulation

and mixing. The top of the cells were connected through two

capillary viscometers for low and high range viscosity measure-

ments and a digital density measuring cell. The bypass loop

allowed the measurement of either the viscosity or density of the

liquid phase from the top or bottom of both cells.

To initialize the experiment, half of the window cell was filled

with bitumen and the rest filled with solvent (carbon dioxide).

The fluids were drawn from the bottom of the window cell by

the gear pump and allowed to flow through the blind cell, viscom-

eter, and density measuring cell, followed by spraying at the top ofthe window cell. This procedure was used to mix the fluids in the

Fig. 3. Equilibration cell designed by Fu et al. [7].

Fig. 4. Mixing and agitation mechanism in setup designed by Fu et al. [7].



5/11

system and saturate the bitumen with carbon dioxide. If the initial

amount of carbon dioxide was not sufficient to saturate the oil, fur-ther carbon dioxide was introduced into system.

When the pressure remained constant, it was assumed that

equilibrium was achieved. Excess carbon dioxide was purged outat a constant pressure, and the system was left for at least 12 h.

Fig. 5. Experimental setup designed by Svrcek and Mehrotra [8].

Fig. 6. Experimental setup designed by Sayegh et al. [9].



6/11

The viscosity and density of the saturated phase at the top and bot-

tom portions of the blind cell were measured. The saturated bitu-

men sample could be taken from either the top or bottom of the

cells by using the sampling valve.

Abedi et al. [10] used an indirect approach for phase behavior

study using X-ray imaging. They developed an X-ray view cell

apparatus for studying the phase behavior of complex organic flu-

ids. Use of this apparatus provided the ability of determining indi-vidual phase densities and compositions, without sampling, over a

broad range of temperatures and pressures. This apparatus utilized

transmitted X-rays, instead of visible light, as the basis for phase

detection. Thus, it was not restricted to fluids that were transpar-

ent to visible light, and it could operate over a broader temperature

range than the classic technique. Another feature of the cell was

that gas could be added continually. This new apparatus had ex-

tended the temperature and pressure range of the classic tech-

nique to 452 C and 28 MPa, respectively.

The schematic diagram of the apparatus is shown in Fig. 7. It

had three key elements: a polychromatic X-ray source, the variable

volume view cell, and the image capture, processing, and viewing

system. The entire setup, except the image processing and viewing

components, was placed in a lead-lined cabinet. The X-rays emit-

ted by the tungsten source and transmitted through the walls of

the view cell were focused with an image intensifier, converted

to visible light using a fluorescent screen and visualized by a

high-resolution video camera.

The number of phases present, other than dispersed solidphases, was determined visually, and the image analysis measure-

ments were performed automatically on portions of the images se-

lected manually.

In a recent study, Badamchi-Zadeh et al. [11] used DB Robinson

Jefri PVT Cell to measure the solubility of Athabasca bitumen

with propane and carbon dioxide, as shown in Fig. 8. The heart

of apparatus was transparent equilibration cell which surrounded

in pressurized hydraulic fluid. Magnetic mixer provided an effi-

cient agitation and floating piston allowed to adjust the equilib-

rium volume. The volume of cell could be measured using

calibrated cathetometer positioned through the cell window. The

DigitalStore

Computer

ADC

Digital to ntsc

Converter

Video

Typewriter

Video

Recorder

Vga Monitor

Colour

Monitor

Heater Control

Panel

Generator

X-ray Image

Intensifier

Camera

Control

Signal View

Cell

PressureGauge

Philips

mcn-167

x-ray

Lead Cabinet

Fig. 7. Experimental setup designed by Abedi et al. [10].

Fig. 8. DB Robinson Jefri PVT cell used by Badamchi-Zadeh et al. [11].



7/11

maximum volume of cell was 100 cm3 and its maximum

operational pressure and temperature were 69 MPa and 200 C.

The inline viscometer (Viscopro2000 Cambridge) and density

measuring cell (Anton Paar DMA 5000) measured the density and

viscosity of saturated phase which was displaced from PVT cell.

A pycnometer was used to take liquid sample for solubility mea-

surement and further analysis.

To conduct an experiment, a specific mass of solvent and bitu-men were charged into PVT cell. The mass fraction was calculated

based on volume and density measurement. The solvent and bitu-

men were mixed at liquid phase to expedite mixing process and re-

duce the equilibration time. They measured the PVT cell volume

from pump displacement and cathetometer reading. For a given

composition, Badamchi-Zadeh et al. [11] measured the saturation

pressure in two steps. The first step was to estimate the saturation

pressure while more accurate pressure measurements were ob-

tained in the second step. The pressure of the PVT cell was de-

creased by gradual expansion of cell volume. They measured the

pressure and volume of cell at constant time intervals. Then, by

plotting pressure versus specific volume, the bubble point was

estimated from the change in slope of pressurevolume plot. This

method gave the approximate saturation pressure; because, the

system was not at equilibrium during the volume expansion. In

the second step, the system was compressed and equilibrium

was established. Then, the pressure was decreased step wise and

after each step, the system was allowed to reach the equilibrium

and the pressure became stable. Addition to saturation pressure,

they measured the density and viscosity of saturated phase during

their experiments.

The apparatuses of Abedi et al. [10] and Badamchi-Zadeh et al.

[11] were the only ones that could detect more than one liquid

phase; whereas, the other setups explained here had no capability

of identifying second liquids. The Abedi et al. apparatus detected

the number of phases; however, it could not measure the physical

properties, such as viscosity and composition, of the different

phases. In Badamchi-Zadeh et al. apparatus, the equilibration cell

volume was less than 100 cm3. Hence, if more than one liquid

phase exists, the volumes of the phases were relatively small to

measure the phase properties. In addition, if there is more than

two phases at the equilibrium condition, the solvent to bitumen

(S/B) ratio in the feed affects the final phase properties. Most of

above-mentioned experimental apparatuses did not have the capa-

bility of measuring the mole or weight fraction of feeding fluids.

3. Experimental apparatus

The composition, density, and viscosity of the each phase in a

saturated bitumen/solvent system are the basic data for phase

behavior study. The apparatus has been designed to acquire the

experimental data of the following information for various sol-

vent/bitumen systems at a wide range of temperatures and

pressures:

(1) Solubility of solvents in bitumen.

(2) Number of phases, volume ratios and compositions of each

phase (gas chromatography, GC, of evolved gas; B.P.

distribution; and, saturates, aromatics, resins and asphalt-

enes, SARA, characteristics of the evaporation residue) at

equilibrium.

(3) Viscosity and density of the saturated phases.

The schematic diagram of the apparatus is shown in Fig. 9. It

consists of feeding cells, an equilibration cell, four sampling cells,

a density measuring cell, a viscometer, and two Quizix automated

pressure activated pumps. The Quizix pumps charge and discharge

water to displace the fluids or keeping the pressure constant. The

equilibration, sampling, and feeding cells are equipped with the

pistons to prevent the contamination of the mixture with water.

The pistons are sealed with the Viton o-rings supported by the

Teflon backup rings.

14

14

70 oC

835 cp0.835 gr/cc

1. Blue M Oven

2. Evaluation Unit (mPDS 2000 v3)

3. Evaluation Unit (ViscoPro 2000)

4. Connect to Computer

5. Density Measuring Cell

6. Viscometer

7. Pressure Transducer

8. Sample Port

1

23

56

44

7

8

9 9 9 9

10

11 11

12

13

15

9. Sampling Cell

10. Equilibrium Cell

11. Feeding Cell

12. Heater

13. Temperature Controller

14. Quizix Pump

15. Computer

Fig. 9. The proposed apparatus for the phase behavior study of bitumen/solvent systems.



8/11

The equilibration and sampling cells, density measuring cell,

and viscometer are placed in a temperature-controlled Blue M

oven. The two pumps (Quizix pumps) control system pressure.

The rocking action of the equilibration cell with the rolling ball

expedites the mixing of solvent and bitumen and reaching equilib-

rium condition. Hu [22] used free rolling ball to investigate the

equilibrium properties of aqueous solution. His study confirmed

that the addition of the free-rolling ball can significantly decreasethe equilibration time. The density measuring cell and viscometer

are used for phase detection, which shows a clear separation of the

phases and allows for accurate phase volume measurements. The

density measuring cell can detect any phases which passing

through it; this feature allows us to detect the phases even with

very small volume. However, if the volume of phase be less than

10 cm3, it is not possible to take a phase sample. In this case, the

experiment is repeated with the same initial composition but high-

er initial volume of bitumen and solvent. Commercial PVT systems

require a subjective visual observation for phase detection;

whereas, this apparatus does not. Data is produced directly and

does not require subjective evaluation.

The rocking equilibration cell has a maximum volume of about

900 cm3, which allows sufficient saturated phase volume for mea-

surement of physical properties, such as density and viscosity. In

addition, it provides ease of phase detection and enough phase

volumes for their further analyses. The Quizix pumps charge and

discharge the fluids with an accuracy of 0.001 cm3. The density

measuring cell and viscometer are installed in series to improve

the phase detection. Their in-line measurements provide data of

higher accuracy than sending very small samples to the viscometer

and density measuring cell separately. In case of solid formation

[23,24] such as asphaltene or wax, the solid precipitates around

the rocking ball. When the cell is placed in upward position, the

solid settles down at the bottom of rocking cell. After each

experiment, the rocking cell is opened to check for asphaltene

precipitation.

The sample fluid is discharged from the top of the rocking cell

through the viscometer and density measuring cell, while main-taining the temperature and pressure constant. In this design, the

sample volume is enough large so that a visual evaluation of

phases is not required. This methodology allows the detection of

the phase variation within the system as the data is collected from

the viscometer and/or density measuring cell. The density measur-

ing cell and viscometer have the capability of detecting small

changes in density and viscosity over a wide range of pressures

and temperatures.

The Anton Paar custom density measuring cell has been used,

and it can measure the fluid density in the range of 03 g/cm3 with

an error of 0.0010.0001 g/cm3 (dependent on the measuring con-

ditions) in a temperature and pressure range of10 to +200 C and

070 MPa (010,000 psi), respectively.

The density measuring cell was calibrated using nitrogen andwater for pressures from 0 to 13.79 MPa (02000 psi g) and tem-

peratures between 40 and 190 C. The data for the densities of

nitrogen and water at specific temperature and pressure were

taken from National Institute of Standards and Technology (NIST)

database. The calibration can be extended to higher pressures

(40 MPa). The accuracy of density measurements were examined

with pure hydrocarbons and standard fluids. The density measure-

ments are precise to 0.0005 g/cm3.

The Cambridge viscometer has the capability to measure

viscosity in the range of 0.210,000 cp with an accuracy of 1.0%

of full scale and temperature and pressure up to 315 C and

140.6 MPa (20,000 psi), respectively. It was factory calibrated;

the accuracy of measurements was tested with pure hydrocarbons

and standard fluids. The average error for the measurements wasless than 5%.

Effective mixing, through agitation by rocking, results in a

reduction in the time required to reach equilibrium. Conducting

experiments in a significantly reduced time provides the opportu-

nity to undertake parallel experiments in phase equilibration,

phase sampling, and measurements of phase density and viscosity.

3.1. Experimental procedure

Prior to each experiment, the entire system is thoroughly

cleaned to remove any contaminant, such as oil and solid particles.

Toluene, acetone, and similar solvents are used to clean and re-

move bitumen, water, and any contaminants from the cells. To

clean inside of the cells, it is possible to easily disassemble the cells

and remove them completely. Then, to ensure no contaminants are

left inside the system, cells and lines are successively evacuated

and flushed with dry helium.

Bitumen is charged into the equilibration cell using the two

Quizix pumps. By measuring the volume and density of bitumen

at a constant temperature and pressure, the mass of the bitumen

inside the equilibration cell is obtained. The solvent is then charged

into the cell with the same procedure. Thus, the mass fraction of

the injected fluids is known. To measure the solubility at a specific

temperature and pressure, the experimental pressure and temper-

ature are fixed: the Quizix pump keeps a constant pressure with an

error of less than 5 kPa.

The equilibration cell is rocked to achieve effective mixing and

reach the equilibrium condition for the bitumen/solvent system.

The required equilibration time depends on the experimental con-

ditions, such as pressure and temperature, as well as solvent and

bitumen properties. Bitumen viscosity is the key factor for the

equilibrium time. For instance, at a high temperature (>80C),

the equilibration time is much less than a low-temperature condi-

tion. This is due to the high bitumen viscosity, which is lower at

higher temperatures, allowing for easier and more effective mix-

ing. During the mixing period, the volume of water, which is

charged or discharged to keep a constant pressure in the equilibra-

tion cell, is recorded. When there is no change in the cumulativevolume of water, equilibrium is achieved.

To discharge the saturated bitumen from the top of the rocking

cell, the equilibration cell is first kept in an upright position (verti-

cal position) for a few hours to obtain single bulk volume of each

phase vertically segregated in the order of phase density. Then,

all the lines connecting the sampling cells to the equilibration cell

are filled with helium gas at equilibrium pressure (helium, as a car-

rying gas, has no effect on G.C. analyses). Helium and equilibrium

fluid are in contact in the line not in the cell; therefore, due to small

contact area (tube area $0.012 cm2) the helium gas has no signif-

icant effect on the equilibrium properties. In addition, to have no

sample phase contamination with helium, about 1015 cm3 of

each phase is purged before phase sampling. Now, the equilibrium

fluids are discharged through the density measuring cell and vis-cometer, while maintaining a constant temperature and pressure.

The pressure is measured by both the in-line and the Quizix pump

pressure transducers. The pressure difference exerted by the fric-

tion of the pistons was found to less than 70 kPa (10 psi). The value

reported by the in-line pressure transducer, which is the exact sys-

tem pressure, is reported as equilibrium pressure.

The phase samples are collected with steady readings of the vis-

cometer and the density measuring cell; any change in density and

viscosity indicates a passage of a phase boundary through the mea-

suring instruments. Liquids and vapor phases are transferred into

sampling cells 13, and the last sampling cell is used to purge

the phase boundary portion and clean the transition between the

phases. The heavier phase can completely displace the lighter

phase, which vertically segregated in the order of phase density,results in clean samples with sharp density variation. The volume



9/11

of each phase is measured by monitoring the volume of water

charged to the equilibration cell. Saturated samples can be col-

lected through the sampling port for compositional analysis or fur-

ther studies.

To measure the solubility of the saturated liquid(s), the col-

lected samples are flashed at atmospheric pressure. The volume

of the evolved gas is measured by the Chandler Engineering Gas-

ometer (Model 2331) with 0.2% accuracy of the reading. Then,the solubility is calculated using two methods: volumetric and

mass conservation. The former method is on the basis of the vol-

ume measured by the Gasometer. Having the density of the gas

at atmospheric condition, the mass of solvent (evolved gas) is cal-

culated. The latter is on the basis of the weighting the sample be-

fore and after evolving the solvent.

3.2. Experimental results

3.2.1. Vaporliquid

The binary system of propane and n-decane was selected for the

vaporliquid system. The saturation pressure and phase composi-

tion were measured at different temperatures. The results were

compared with the experimental data reported by Reamer andSage [25] at three different conditions.

The experiment was conducted based on the experimental pro-

cedure previously discussed. When equilibrium was achieved, the

equilibration cell was placed in a vertical position for phase align-

ment. While the equilibrium fluid was discharged from the equili-

bration cell, its density was measured continuously. Fig. 10 shows

the density measurement during the sampling. The density in early

time was about 0.003 g/cm3, which shows the density of helium in-

side the lines. The flow rate to push the fluids was too low (0.1

3 cm3/min) to keep the cylinder at equilibrium. This flow rate

was obtained by trial and error. This was the maximum rate in

which the fluids were displaced at constant pressure. It depends

on the equilibrium fluid properties and apparatus specification

such as o-ring and line diameter.After about 20 min, the gas phase was detected at the density

measuring cell. There was a sharp change in density from $0.003

to $0.05 g/cm3 which shows the density of a vapor mixture con-

taining mostly propane. The density measuring cell detected the

two different gases with a small density difference. Discharging

was continued to detect the other phase, which was liquid. The

sharp increases in density from $0.05 to $0.5 g/cm3 confirmed

the liquid phase.

Vapor phase composition was measured using gas chromatog-

raphy and it was propane (for all experiments, more than 99.8%

propane). To obtain the composition of propane in liquid phase,

the saturated liquid was flashed at atmospheric condition. The

compositional analysis indicated that the evolved gas was pure

propane (more than 99.5%). Hence, the mass of dissolved gas could

be measured from the volumetric data. Table 2 summarizes the

propane composition in the liquid phase. The experimental data

by Reamer and Sage [25] for this binary system is also shown for

comparison.

3.2.2. LiquidliquidThe liquidliquid mixing experiment was performed to investi-

gate the capability of the experimental setup in identifying two liq-

uids. Alcohol/hydrocarbon and alcohol/water systems were used

for measuring purposes. The measured density was compared with

literature data.

3.2.2.1. 1-Butanol/water system. A specific volume of 1-butanol and

water was mixed at a temperature of 25 C and atmospheric pres-

sure. After equilibration, all lines were filled with nitrogen, and the

mixture was then displaced through the density measuring cell,

with the density being continuously measured. Fig. 11 illustrates

the experimental results for the density measurement during the

sampling. As depicted in the figure, at the start of the sampling,

nitrogen flowed though the density measuring cell, and its density

was close to zero; then the first liquid passed through the density

measuring cell, there was a sharp change in density. There was a

second jump for the second liquid. The measured densities for both

liquids were compared with results reported by Hill and Malisof

[26] and are summarized in Table 3. The change in density from

liquid 1 to liquid 2 was not very sharp. This was an indication that

the vertical segregation between them was not complete. The data

suggested that fine droplets of the upper liquid were still

suspended in the densest lower liquid. This situation could be alle-

0

0.1

0.2

0.3

0.4

0.5

0 1 2 3 4 5

Time, hr

Density,gr/cm

3a

Fig. 10. Density measurements for vaporliquid equilibria: propane/n-decanesystem.

Table 2

Propane composition (mole fraction) in saturated liquid phase for propane/n-decane

system.

Propane molefraction in liquid

T= 71.1 C T= 104.4 C T= 137.8 C

P= 1.379 MPa P= 2.758 MPa P= 4.137 MPa

Reamer and Sage [25] 0.5899 0.7003 0.7023

This study 0.580 0.699 0.707

0

0.2

0.4

0.6

0.8

1

0 10 20 30

Time, min

Density,gr/cm

3a

Fig. 11. Density measurement for liquidliquid equlibria: 1-butanol/water system.

Table 3

Density measurement for 1-butanol/water system at 25 C and 0.101325 MPa.

Phase density Hill and Malisof[26] (g/cm3) This study (g/cm3)

Alcohol phase 0.8450 0.835

Water phase 0.9865 0.981



10/11

viated by leaving the equilibration cell at vertical position for long-

er time.

3.2.2.2. Methanol/n-decane. A specific volume of methanol and n-

decane was mixed at a temperature of 25 C and atmospheric pres-sure. As before, all lines were filled with nitrogen; and, the mixture

was then displaced through the density measuring cell, while the

density was measured. Fig. 12 shows the density variation for this

case. As the figure shows, at first, nitrogen flowed through the den-

sity measuring cell, and its density is close to zero. When first li-

quid passed through the density measuring cell, there was a

sharp change in density. The density became stable when the

nitrogen was displaced by first liquid. A second jump occurs when

liquid 2 reached the density measuring cell.

3.2.3. Vaporliquidliquid

The ternary system of ethane, n-decane, and methanol was

selected, and the number of phases was measured at a specific

temperature and pressure. The experimental results for thetemperature of 37 C and pressure of 1.207 MPa are presented.

Table 4 summarizes the feeding properties of three components

and the composition of each component in the mixture.

The fluids were injected in a liquid state into the equilibration

cell, and the injected volume and corresponding composition were

measured. Thevolume and composition of each component is given

in Table 4. Nitrogen was used to pressurize the line and discharge

the system at a constant pressure (1.207 MPa). Fig. 13 illustrates

the density measurement for this system. The density in early time

was about 0.013 g/cm3 which shows the density of nitrogen inside

the lines. The flow rate to push the fluids was kept constant (3 cm

3

/min) to maintain the system at equilibrium. After about 5 min, the

gas phase (mostly ethane) was detected at the density measuring

cell. There was a sharp change in density from 0.013 to 0.015 g/

cm3, which shows the density of a mixture which was almost all

ethane. Fig. 13b shows that the transition from nitrogen to the va-

por phase (ethane) was clearly detected by density measuring cell.

This result confirmed that thedensity measuringcell canaccurately

detect two different gases with very small density differences.

Fig. 13a shows the density measurement for the entire experi-

ment. The two liquid densities were 0.682 and 0.735 g/cm3, respec-

tively. There was a sharp transition in the density measurement,

which can be used to identify the two liquids, as well as two vapor

phases.

3.2.4. Solubility of propane in bitumen

To examine the capability of apparatus for bitumen/solvent

phase behavior study, the solubility of propane in bitumen at dif-

ferent conditions were measured. The propane (99.5 wt.% purity)

used in these measurements was supplied by Praxair. The density

and viscosity of the bitumen at 50 C was measured by an Anton

Paar density measuring cell and Cambridge viscometer, respec-

tively. The measured density and viscosity were 0.992 g/cm3 and

9845.9 mPa s, respectively.

The procedure to charge the equilibration cell was described in

Section 3.2. The bitumen was preheated and transferred directly to

the density measuring cell and viscometer. The properties of the

bitumen were measured to calculate the mass of bitumen charged

into the equilibration cell. The bitumen and solvent were displaced

at constant pressure and temperature to have accurate amount ofthe components. The experiments at pressure of 4 MPa and three

different temperatures, 50, 100, and 150 C, were conducted.

The procedure for equilibration and discharging the equilibrium

fluids were described in Section 3.2. It was found that at 100 C and

150 C, vaporliquid equilibrium exists while at 50 C, the liquid

liquid was observed. The properties of the saturated phases as well

as the solubility are summarized in Table 5.

The phase detection during the displacement of the equilibrium

phases were done on the basis of the density measurements.

Fig. 14 illustrates the phase change during the discharging of the

equilibrium fluids at 100.5 C and 4 MPa. The total composition

of the propane in the mixture at initial stage was 40% weight.

0

0.2

0.4

0.6

0.8

1

0 5 10 15 20

Time, min

Density,gr/cm

3a

Fig. 12. Density measurement for liquidliquid equlibria: methanol/n-decane

system.

Table 4

Initial composition and properties of each component for vaporliquidliquid system.

Component Volume

(cm3)

Pressure

(MPa)

Density

(g/cm3)

Mole Molecular

weight (g/mol)

Ethane 53.6 4.924 0.3366 0.6 30.07

n-Decane 195.9 0.101 0.7265 1 142.29

Methanol 81.0 0.101 0.7918 2 32.05

0

0.2

0.4

0.6

0.8

1

0 50 100 150

Time, min

Density,gr/cm

3a

a

0

0.005

0.01

0.015

0.02

0 5 10 15 20

Time, min

Density,gr/cm

3a

b

Fig. 13. Density measurement for vaporliquidliquid system: (a) entire experiment and (b) vapor transition.



11/11

The total volume of mixture before mixing was 334.18 cm3 and the

equilibrium volume was 255.03 cm3 (at equilibrium temperature

and pressure). As depicted in Fig. 14, the volume of each phase

and corresponding density were measured during the experiment.

4. Conclusion

A new experimental apparatus for heavy oil and bitumen has

been tested for the study of vaporliquid, liquidliquid, and va-

porliquidliquid equilibria. The technique and apparatus de-

scribed here have already provided, and continue to generate,

data of value that are unattainable in other ways and offer much

promise for the future. The density measurement is an accurate

method for phase detection; and, if it is coupled with the viscosity

measurement, it will provide a unique method for phase behavior

study. The preliminary tests show the experimental setup has the

capability of detecting of the separate phases, as well as generating

reliable data for phase behavior, of different vaporliquid, liquid

liquid, and vaporliquidliquid systems.

The unique feature of the new setup in measuring the accurate

volume of feeding fluids and equilibrium phases provides the abil-ity to not only acquire the volumetric data for equilibrium phases,

but also obtain the effect of the solvent/bitumen feeding ratio on

the composition and volume of the phases and other properties.

Acknowledgment

This work has been carried out as a part of the SHARP (Solvent/

Heat-Assisted Recovery Processes) research consortium executed

at the University of Calgary. The consortium was initiated by Dr.

Tadahiro Okazawa, a retired Senior Research Advisor of Imperial

Oil Resources Ltd., he had been keenly aware of the serious lack of

physical data which couldotherwise augment effectiveapplications

of these recovery processes. Dr. Okazawa is acknowledged for his

being responsible for drawing the blue prints of this research con-sortium including the original design of the unique experimental

apparatus. This has provided a stepping stone to the further

advancement achieved in this study. The authors wish to express

theirappreciation for the financialsupport of all member companies

of the SHARP consortium: Alberta Innovates Energy and Environ-

ment Solutions, Athabasca Oil Sands Co., Chevron Energy Technol-

ogy Co., Computer Modeling Group Ltd., ConocoPhillips Canada,

Devon Canada Co., Foundation CMG, Husky Energy, Japan Canada

Oil Sands Ltd., Laricina Energy Ltd., Nexen Inc., OSUM Oil SandsCo., Penn West Energy, Statoil, SuncorEnergy, and Total E&PCanada.

The authors also thank professors Gordon R. Moore, Raj Mehta, and

Mehran Pooladi-Darvish and the technical support of Kees Van Fra-

assen and Dan Marentette.

References

[1] Butler RM, Stephens DJ. The gravity drainage of steam-heated oil to parallelhorizontal wells. J Can Petrol Technol 1981;20(2):906.

[2] Butler RM. A new approach to the modelling of steam-assisted gravitydrainage. J Can Petrol Technol 1985;24(3):4251.

[3] Butler RM, Mokrys IJ. Solvent analogy model of steam-assisted gravitydrainage. AOSTRA J Res 1989;5(1):1731.

[4] Mokrys IJ. The rise of interfering solvent chambers: solvent analog model ofSAGD. M.Sc. Thesis, Calgary, AB: University of Calgary; 1989.

[5] Butler RM, Mokrys IJ. A new process (VAPEX) for recovering heavy oils usinghot water and hydrocarbon vapour. J Can Petrol Technol 1991;30(1):97106.

[6] Jacobs FA, Donnelly JK, Stanislav J, Svrcek WY. Viscosity of gas saturatedbitumen. J Can Petrol Technol 1980;19(4):4650.

[7] Fu CT, Puttagunta VR, Vilcsak G. Vapour liquid equilibrium properties forpseudo-binary mixtures of CO2 Athabasca bitumen and N2 Athabascabitumen. AOSTRA J Res 1985;2(2):7381.

[8] Svrcek WY, Mehrotra AK. Properties of Peace River bitumen saturated withfield gas mixtures. J Can Petrol Technol 1989;28(2):506.

[9] Sayegh SG, Rao DN, Kokal S, Najman J. Phase behaviour and physical propertiesof lindbergh heavy oil/CO2 mixtures. J Can Petrol Technol 1990;29(6):319.

[10] Abedi SJ, Cai HY, Seyfaie S, Shaw JM. Simultaneous phase behaviour, elementalcomposition and density measurement using X-ray imaging. Fluid PhaseEquilib 1999;158160:77581.

[11] Badamchi-Zadeh A, Yarranton HW, Svrcek WY, Maini BB. Phase behaviour andphysical property measurement for VAPEX solvents: part I. Propane andAthabasca bitumen. J Can Petrol Technol 2009;8(1):5461.

[12] Mehrotra AK, Svrcek WY. Measurement and correlation of viscosity, density

and gas solubility for Marguerite Lake bitumen saturated with carbon dioxide.AOSTRA J Res 1984;1(1):5162.[13] Mehrotra AK, Svrcek WY. Viscosity, density and gas solubility data for oil sand

bitumens. Part I: Athabasca bitumen saturated with CO and C2H6. AOSTRA JRes 1985;1(4):2638.

[14] Mehrotra AK, Svrcek WY. Viscosity, density and gas solubility data for oil sandbitumens. Part II: Peace River bitumen saturated with N 2, CO, CH4, CO2 andC2H6. AOSTRA J Res 1985;1(4):26979.

[15] Mehrotra AK, Svrcek WY. Viscosity, density and gas solubility data for oil sandbitumens. Part III: Wabasca bitumen saturated with N2, CO, CH4, CO2 and C2H6.AOSTRA J Res 1985;2(2):8393.

[16] Mehrotra AK, Svrcek WY. Properties of Cold Lake bitumen saturated with puregases and gas mixtures. Can J Chem Eng 1988;66(4):65665.

[17] Svrcek WY, Mehrotra AK. Gas solubility, viscosity and density measurementsfor Athabasca bitumen. J Can Petrol Technol 1982;21(4):318.

[18] Kariznovi M, Nourozieh H, Abedi J. Bitumen characterization andpseudocomponents determination for equation of state modeling. EnergyFuels 2010;24(1):62433.

[19] Robinson DB, Kalra H, Sim SK. Behavior of bitumenwatergas systems. Final

Report on AOSTRA Research Agreement 43. Edmonton, AB: University ofAlberta; 1980.

[20] Robinson DB, Sim SK. The behavior of bitumen mixture during in-siturecovery. A Progress Report on Agreement 184. Edmonton, AB: University ofAlberta; 1981.

[21] Fu CT, Puttagunta VR, Vilcsak G. Gas solubility of methane and ethane in ColdLake bitumen at in situ conditions. J Can Petrol Technol 1988;27(4):7985.

[22] Hu YF. Solubility of mannitol in aqueous sodium chloride by the isopiesticmethod. J Solut Chem 1998;27(3):25560.

[23] Mousavi-Dehghani SA, Riazi MR, Vafaie-Sefti M, Mansoori GA. An analysis ofmethods for determination of onsets of asphaltene phase separations. J PetrolSci Eng 2004;42(2-4):14556.

[24] Vazquez D, Mansoori GA. Identification and measurement of petroleumprecipitates. J Petrol Sci Eng 2000;26(14):4955.

[25] Reamer HH, Sage BH. Phase equilibria in hydrocarbon systems. Volumetric andphase behavior of the propane-n-decane system. J Chem Eng Data1966;11(1):1724.

[26] Hill AE, Malisoff WM. The mutual solubility of liquids. III. The mutual solubilityof phenol and water. IV. The mutual solubility of normal butyl alcohol andwater. J Am Chem Soc 1926;48(4):91827.

Table 5

Initial bitumen/propane ratio and corresponding equilibrium properties for bitumen/

propane system.

Temperature

(C)

S/B

ratio*Solubility (wt.% C3) Saturated phase properties

Phase 1 Phase 2 Viscosity

(mPa s)

Density

(g/cm3)

Bitumen rich

(phase 2)

Phase 1 Phase 2

50.9 1/1 62.5 21.5 127.0 0.586 0.860

100.5 2/3 Pure C3 22.9 2.7 0.105 0.775

149.8 1/4 Pure C3 8.7 5.4 0.065 0.849

* S/B ratio: solvent to bitumen ratio wt/wt.

0

0.2

0.4

0.6

0.8

1

0 100 200 300

Volume, cm3

Density,gr/cm

3a

Fig. 14. Density versus volume for bitumen/propane system at 100.5 C and 4 MPa.


Artigo Hosiberto

Documents

Transcript of Artigo Hosiberto