pvt and viscosity measurements for lloydminster-aberfeldy

8/14/2019 PVT and Viscosity Measurements for Lloydminster-Aberfeldy

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Copyright 2002, SPE/PS-CIM/CHOA International Thermal Operations and Heavy OilSymposium and International Horizontal Well Technology Conference

This paper was prepared for presentation at the 2002 SPE International Thermal Operationsand Heavy Oil Symposium and International Horizontal Well Technology Conference held inCalgary, Alberta, Canada, 47 November 2002.

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Abstract

A solvent-assisted gravity drainage process (Vapex) forrecovery of heavy oil or bitumen offers high recoveries and

promising rates of oil production. In order to predict process

performance, data on solvent-oil solubility and on the

viscosity of solvent-oil mixtures must be obtained.

The solubility of selected gasses in Lloydminster Aberfeldy oil

and in a Cold Lake oil was measured. The gasses used were:

CH4, C2H6, C3H8 and CO2. Measurements were done at

reservoir temperature. The data were regressed using thePeng-Robinson equation of state, which was used to generate

k-values expressing the solubility of the gas-oil systems.

Regressing the Peng-Robinson equation to the measured datagenerated interaction coefficients for the systems measured.

These coefficients were used with the equation to generate k-

value or solubility tables at other conditions. Measured

viscosity data were used to confirm the usefulness of the

Puttagunta viscosity correlation for propane-based heavy oilsystems. The work confirmed the formation of two liquid

phases in the oil-propane system at high solvent loading. The

measurements also confirmed the large viscosity reductionsavailable (100:1 200:1) by saturating oil with light

hydrocarbons. A viscosity increase in one oil-propane system

was observed at high solvent loading, suggesting possibleasphaltene precipitation and/or deposition on the walls of the

capillary viscometer tube.

These observations confirmed the need to study phase

behaviour and asphaltene deposition in the oils at high solven

loading, as well as obtaining solubility and viscositymeasurements. The data have been used to perform numerica

simulations of Vapex and other solvent-based processes, and

to perform predictions of field process performance.

INTRODUCTION

Thermal recovery processes have been used successfully on

many Alberta bitumen and heavy oil reservoirs. Some

reservoirs, however, are not suited to thermal processes. This

may be due to depth, unfavorable mineralogy, bottom water

thin pay sections, or a combination of these factors. For thesereservoirs, a non-thermal process may be more suitable. The

most likely candidate is a Vapex-type process, where oil is

contacted by solvent vapour. The vapour dissolves in the oil

and diluted oil drains to a production well.

The application of this technology to heavy oil recovery

requires confident prediction of the process performance for afield-scale operation. This in turn requires knowledge of the

mechanisms active in the process, and of the magnitude of

each of these mechanisms. Mechanisms identified to date

include solubilization of the solvent in oil, mass transfer fromvapour to liquid phases by diffusion, mixing of diluted and

undiluted oil by diffusion and dispersion, reduction of the oi

viscosity by solvent dilution, and upgrading of the oil by

asphaltene precipitation and deposition. This work measuredsolubility and viscosity of several oil-solvent systems.

DESIGN OF EXPERIMENT

The experiment was performed in a PVT apparatus

constructed from standard components. Figure 1 illustrate

the PVT system and its associated hardware. The windowed

cell used for the measurements was a Jergusson cell rated to2600 psi @ 100 F (17.9 MPa @ 38C). The cell (Figure 2)

was equipped with a re-circulating gas pump to bubble gas

through the oil, and thus speed equilibrium. The entire

SPE/Petroleum Society of CIM/CHOA 79018

PVT and Viscosity Measurements for Lloydminster-Aberfeldy and ColdLake Blended Oil SystemsTed W.J. Frauenfeld /Alberta Research Council SPE, Gerald Kissel /Alberta Research Council,Shibing (Wendy) Zhou /Umicore Canada


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2 SPE/PS-CIM/CHOA 79018

assembly was enclosed in a heated bath to maintain the

required temperature. Auxiliary equipment included:

Oil and gas supply accumulators, oil transfer accumulators,

capillary viscometer, oil flashing vessel, gas meter, and a

Western Atlas pump to perform transfer operations. Pressures

and temperatures were logged by a data logging system.

Phase Behaviour Calculations

Calculations to predict phase behaviour and solubility in the

reservoir oil were performed using the Peng-Robinson

equation of state as expressed in CMGs WinProp package(2).

The viscosity of the oil-solvent mixture was then calculatedusing the Puttagunta correlation (1).

EXPERIMENTAL PROCEDURE

All measurements were done using a windowed equilibriumcell equipped with a re-circulating gas pump. The cell was

enclosed in a constant temperature bath for temperaturecontrol. (Figure 1) The experiment was started by heating the

cell to the desired temperature. Oil was then pumped into the

cell until the level reached half way up the cell window. Gas

was then admitted to the cell. Gas pressure was brought up

the first target, and the gas re-circulating pump was started.The gas pressure declined over time as the gas dissolved in the

oil. Periodically more gas was added to the system to

maintain the target pressure. When the gas pressure did not

change with time, the cell was considered to be at equilibrium.GOR and viscosity measurements were then carried out.

Viscosity measurements were performed by first transferringthe oil/solvent mix from the cell to the oil transfer

accumulator. The oil was then forced through the capillaryviscometer by running the Western Atlas pump at a known

rate. The pressure drop across the capillary tube was

measured, and the viscosity was calculated.

Oil from the viscometer outlet was flashed into the collecting

vessel. Off gas was measured and the oil sample wasweighed. The gas volume was corrected for atmospheric

pressure and temperature, and the GOR was calculated.

Experimental Results

The first oil/solvent system measured was ethane dissolving in

blended Cold Lake/Lloydminster oil. The oil was the same aswas used in a series of scaled model experiments done atARC(3). The results are shown in Table 1. Solubility was

measured for pressures from 750 to 2650 kPa. The average

deviation from the best fit to Peng-Robinson on five

measurements was 2.9%. Solubility measurements areillustrated in Figure 3. Viscosity measurements are illustrated

in Figure 4.

The second system measured was a Cold Lake/Lloydminsterblend oil and Propane. This oil was used in the previous set of

measurements. The results are shown in Table 2. Solubility

was measured for pressures from 223 to 543 kPa. The average

deviation from the best-fit calculated values was 4.03%Solubility measurements are illustrated in Figure 5. Viscosity

measurements are illustrated in Figure 6.

The third system measured was a Lloydminster Aberfeldy

oil/methane system. The measurements were done by B. Hanat Beijing University. The results are shown in Table 3

Solubility was measured for pressures from 993 to 5117 kPaThe average deviation from the best-fit calculated values was

4.2%. Results are illustrated in Figure 7.

The fourth system measured was a Lloydminster Aberfeldyoil/ethane system. The measurements were also done a

Beijing University. The results are shown in Table 4

Solubility was measured for pressures from 510 kPa to 3100

kPa. The average deviation from the best-fit calculated value

was 5.1%. Measurements are illustrated in Figure 8.

The fifth system measured was a Lloydminster Aberfeldyoil/propane system. The measurements were done at Beijing

University. The results are shown in Table 5. Solubility was

measured for pressures from 110 kPa to 517 kPa. The average

deviation from the best-fit calculated value was 3.4%

Measurements are illustrated in Figure 9.

The final system measured was a Lloydminster Aberfeldy

oil/carbon dioxide system. The measurements were done a

Beijing University. The results are shown in Table 6Solubility was calculated for pressures from 1067 to 4489 kPa

The average deviation from the best-fit calculated value was

4.2%. Measurements are illustrated in Figure 10.

Viscosity Measurement

Our apparatus was equipped with a capillary tube viscometerThis enabled measurement of live oil viscosity at pressure and

temperature. Measurements were completed for the blend oi

system for ethane and propane loading. The results of these

measurements are shown in Figure 4 and Figure 6. Themeasurements were used to validate the Puttagunta correlation

for use in propane solubility calculations. It is significant tha

the solubility of propane in blend oil did not change at thehighest pressure (600 kPa), as shown in Figure 11. The

viscosity for this pressure point actually increased slightly, as

shown in Figure 6.

CONCLUSIONS

The data obtained from this work confirmed the suitability o

a re-circulating gas PVT cell for heavy oil measurements. I

confirmed the validity of a single parameter (interactionfactor) regression to fit experimental PVT data. The work also

confirmed the formation of two liquid phases in the oil-

propane system at high solvent loading. The increase inviscosity at the end of the propane measurements suggested


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SPE/PS-CIM/CHOA 79018 3

the formation of asphaltenes, and a possible narrowing of the

viscometer tube. The measurements also confirmed the large

viscosity reductions available (100:1 200:1) by saturating oilwith light hydrocarbons. The work also confirmed

experimental measurements made with an on-line viscometer

on some of the Solvent-Assisted Process experiments. The

data is useful for prediction of the performance of Vapex and

other solvent-based processes.

RECOMMENDATION

ARC will continue to gather data on heavy oils, to supplement

the current database. Data will be extended to cover all gasses

proposed for EOR processes. The capabilities of the re-circulating gas PVT cell should be extended to cover higher

temperatures, to enable measurements suitable for thermal-

solvent processes. We will also develop other PVT

capabilities, in particular to examine swelling and non-linear

mixing in heavy oil/solvent systems. Measurement ofasphaltene precipitation onset and of asphaltene deposition

and plugging are important to understanding some aspects ofVapex performance, and ARC has developed a capability in

this area.

ACKNOWLEDGMENT

The authors would like to acknowledge funding and technical

support from the AACI Research Program. The development

of the PVT equipment is the result of the contributions of

several people, including George Vilcsak, Doug Lillico,Gurdeep Purewal, and Gerald Kissel. The original report and

this manuscript were formatted by Valerie Pinkoski.

NOMENCLATURE

P exp. Experimental pressureX1 exp Experimental gas mole fractionPcalc Pressure calculated by P-R equation(P-Pcalc) difference between experimental and calculated(P-Pcalc)/P dimensionless difference between exp. and calc.

|P-Pcalc| absolute value of pressure difference|P-Pc/P| absolute dimensionless pressure differenceCij interaction coefficient for components i and jk-value equilibrium partitioning coefficient for oil/gas

(P-Pc)avg average pressure difference for a set of tests|P-Pc/P|avg average dimensionless pressure difference

REFERENCES

1. Puttagunta, V.R., Singh, B. and Cooper, E.: A

Generalized Viscosity Correlation for Alberta Heavy Oilsand Bitumens, proceedings 4th UNITAR/UNDP

conference on Heavy Crudes and Tar Sands no. 2, 1988pp. 657-659.

2. Khose, B., Coombe, D., et al: WinProp Phase Property

Program Version 1999 Users Guide, Computer

Modelling Group Ltd., 1999.

3. Frauenfeld, T., Lillico, D., Jossy, C., Rabeeh, S., and

Singh, S.: Evaluation of Partially Miscible Processes for

Alberta Heavy Oil Reservoirs, Journal of CanadianPetroleum Technology, April 1998, p. 17-24.


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Table 1. Solubility of Ethane in Cold Lake Blend Oil

Blend oil C2H6 T=15 C Cij= -0.15

Sample# Pexp. X1 exp. Pcalc. P-P calc P-Pcalc/P |P-Pcalc| |P-Pc/P| X1calc. |X1-X1c| k-value

(kPa) (molar) (kPa) (kPa) (kPa) (molar) (molar) (molar)

1 754 0.2847 1018.7 -264.7 -0.351061 264.7 0.3510610 0.3046 0.0199 3.282992 1163.3 0.3301 1228.3 -65 -0.055875 65 0.0558755 0.3145 0.0156 3.17965

3 1724.3 0.4596 1803.7 -79.4 -0.046047 79.4 0.0460476 0.4425 0.0171 2.25988

4 2163.7 0.5389 2188.8 -25.1 -0.01160 25.1 0.0116004 0.5338 0.0051 1.87336

5 2653.7 0.6268 2646.1 7.6 0.0028639 7.6 0.0028639 0.6282 0.0014 1.59184

(P-Pc)avg ((P-Pc)/P)avg |P-Pc|avg |P-Pc/P|avg |X1-X1c|avg

-40.475 -0.027664 35.42 0.0290969 0.0098

Table 2. Solubility of Propane in Cold Lake Blend Oil

Blend oil C3H8 T=15C Cij= -0.01

Sample# Pexp. X1 exp. Pcalc. P-Pcalc P-Pcalc/P |P-Pcalc| |P-Pc/P| X1calc. |X1-X1c| k-value


1 223.3 0.3227 243.6 -20.3 -0.090909 20.3 0.090909 0.2970 0.0257 3.36700

2 343.9 0.4518 345.4 -1.5 -0.004361 1.5 0.004361 0.4502 0.0016 2.22123

3 424.1 0.5452 420 4.1 0.009667 4.1 0.009667 0.5507 0.0055 1.81587

4 543.6 0.6623 512.9 30.7 0.056475 30.7 0.056475 0.6623 0.0399 1.4241(P-Pc)avg ((P-Pc)/P)avg |P-Pc|avg |P-Pc/P|avg |X1-X1c|avg

3.25 -0.007281 14.15 0.0403534 0.01817

Table 3. Solubility of Methane in Lloydminster Aberfeldy Oil

Aberfeldy oil/CH4 T=19 C Cij= -0.125

Sample # Pexp X1 exp Pcalc P-Pcalc |P-Pcalc| |P-Pc/P| X1calc |X1-X1c| k-value

(kPa) (molar) (kPa) (kPa) Pa) (molar) (molar) (molar)

1 993 0.0662 1066 -73 73 0.07351 0.0618 0.0044 16.1812

2 1979 0.1251 2097.6 -118.6 118.6 0.1186 0.0065 8.43170

3 3028 0.1842 3228.2 -200.2 200.2 0.06611 0.1741 0.0101 5.74382

4 4166 0.2285 4150 16 16 0.00384 0.2292 0.0007 4.36300

5 5117 0.2669 5009.7 107.3 107.3 0.02096 0.2714 0.0045 3.68459

(P-Pc)avg |P-Pc|avg |P-Pc/P|avg |X1-X1c|avg

-53.7 103.02 0.0448740 0.00524


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Table 4. Solubility of Ethane in Lloydminster Aberfeldy Oil

Aberfeldy oil/C2H6 T=19 C Cij= -0.038

Sample # Pexp X1 exp Pcalc P-Pcalc |P-Pcalc| |P-Pc/P| X1calc |X1-X1c| k-value


1 510 0.1984 582.1 -72.1 72.1 0.14137 0.1758 0.0226 5.68828

2 1041 0.3796 1196.2 -155.2 155.2 0.14908 0.3370 0.0426 2.96735

3 2034 0.5932 2084.6 -50.6 50.6 0.02487 0.5828 0.0104 1.71585

4 2586 0.6867 2564.3 21.7 21.7 0.00839 0.6907 0.004 1.44780

5 3103 0.7513 2948.3 154.7 154.7 0.04985 0.7752 0.0239 1.28998


-20.3 90.86 0.07471 0.0207

Table 5. Solubility of Propane in Lloydminster Aberfeldy Oil

Aberfeldy oil/C3H8 T=19 C Cij= -0.036Sample

#Pexp X1 exp Pcalc P-Pcalc |P-Pcalc| |P-Pc/P| X1 calc |X1-X1c| k-value


1 110.3 0.1886 127.2 -16.9 16.9 0.15321 0.1667 0.0219 5.9988

2 206.9 0.327 223.3 -16.4 16.4 0.07926 0.3039 0.0231 3.2905

3 324.1 0.4624 329.2 -5.1 5.1 0.01573 0.4584 0.004 2.18150

4 413.8 0.5479 399.2 14.6 14.6 0.03528 0.5672 0.0193 1.76304

5 517.2 0.6553 494.1 23.1 23.1 0.04466 0.6818 0.0265 1.4667


-0.14 15.22 0.06563 0.01896

Table 6. Solubility of CO2in Aberfeldy oil

Aberfeldy oil/CO2 T=19 C Cij= 0.047

Sample#

Pexp. X1 exp. Pcalc P-Pcalc |P-Pcalc| |P-Pc/P| X1calc |X1-X1c| k-value


1 972.4 0.1743 1067.2 -94.8 94.8 0.09749 0.16 0.0143 6.25

2 1179 0.2081 1292.3 -113.3 113.3 0.09609 0.1914 0.0167 5.2246

3 2090 0.3387 2232.9 -142.9 142.9 0.06837 0.3201 0.0186 3.1240

4 3155 0.4594 3226.6 -71.6 71.6 0.02269 0.4514 0.008 2.2153

5 3710 0.5118 3706.2 3.8 3.8 0.00102 0.5123 0.0005 1.9519

6 4621 0.5897 4489.9 131.1 131.1 0.02837 0.6018 0.0121 1.6616


-47.95 92.916666 0.0523418 0.0117


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Figure 1. Gas Solubility Apparatus Overview


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Figure 2. Recirculating Gas PVT Cell

Solenoid pump

Gas charging valve

Gas flow

Oil sample to flash

Jergussen cell


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Figure 3. Experimental and Calculated Solubility data for C2H6/blend oil System

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 500 1000 1500 2000 2500 3000

Pressure (kPa)

solubility(molar)

0

0.5

1

1.5

2

2.5

3

3.5

k-values(calcula

ted)

Experiment Peng-Robinson k-values


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Figure 4. Cold Lake/Lloydminster Blend Oil/C2H6Viscosity Data @ 15C

Figure 5. Experimental and Calculated Solubility Data for C3H8/blend oil System

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 100 200 300 400 500 600

Pressure (kPa)

Solubility(mol/mol)

0

0.5

1

1.5

2

2.5

3

3.5

4

k-values(calculated)

experiment Peng-Robinson k-values

1

10

100

1000

10000

100000

0.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0

Pressure (kPa)

Viscosity(mPa.s

)


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Figure 6. Cold Lake and Lloydminster oil/C3H8viscosity data

Figure 7. Experimental and Calculated Solubility for Aberfeldy Bitumen/CH4system

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Pressure (kPa)

solubility(molar)

0

2

4

6

8

1012

14

16

18

k-value(calcula

ted)

experiment Peng-Robinson k-value

10

100

1000

10000

100000

0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0

P(kPa)

Viscosity(mPa

.s)

C3 viscosity


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Figure 8. Experimental and Calculated Solubility for Aberfeldy Bitumen/C2H6System

Figure 9. Experimental and Calculated Solubility data for Aberfeldy Bitumen/C3H8System

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 100 200 300 400 500 600 700 800 900 1000

Pressure (kPa)

solubility(molar)

0

1

2

3

4

5

6

7

8

9

10

k-value(calculated)

experiment Peng-Robinson k-value

0

0.2

0.4

0.6

0.8

1

0 500 1000 1500 2000 2500 3000 3500

pressure (kPa)

solubili

ty

(molar

)

-1

1

3

5

7

9

k-

value(calculated)

experimental Peng-Robinson k-value


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Figure 10. Experimental and Calculated Solubility for the Aberfeldy oil/CO2System

Figure 11: Solubility of Propane in Blend Oil vs. Pressure

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

pressure (kPa)

solubility(molar)

0

1

2

3

4

5

6

7

k-value(calculated

)

experimental Peng-Robinson k-value

0.0000

0.2000

0.4000

0.6000

0.8000

1.0000

0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0

abs.Pressure (kPa)

MolefractionC3H8

pvt and viscosity measurements for lloydminster-aberfeldy

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