2009 nano micro structure of bitumen and heavy oil using montreal hasan et al. pdf[1]

8/7/2019 2009 Nano Micro Structure of Bitumen and Heavy Oil Using Montreal Hasan et al. pdf[1]

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N an o-M icro S tructu re of Bitum en an d H eavy O ilU sin g V iscoelastic Properties

M D . An waru l H asan 1 , M ich al Fu lem 2,3 , John M Sh aw 2

1

Department of Mechanical Engineering, University of Alberta2 Department of Chemical Engineering, University of Alberta

Edmonton, Canada3 Insttute of Physics, Academy of Sciences of the Czech Republic, v. v. .,

Cukrovarnick 10, CZ -162 53 Prague 6, Czech Republic

1

In press at energy and fuels


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The purpose of the study is to investigate the nano-microstructure of bitumen using its viscoelastic behavior.

Introduction

The influence of asphaltenes on the rheological properties of fluids is typically studied by mixing solvent extractedasphaltenes with standard solvents or de-asphalted oils.

The question, how closely the behavior of these mixturesresembles that arising in the original hydrocarbon resourcesremains unanswered in the literature.

In this work, we report on the rheological properties of nano-

filtered Athabasca bitumen and Maya crude oil samplesobtained by solvent-free nanofiltration

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Materials and Sample Preparaton

Athabasca Bitumen (Alberta) and Maya Crude oil (Mexico).

Materials:

Sample preparaton

Nanofiltration: 5, 10, 20, 50nm permeates and retentates.

Asphaltene wt.%: 0 to 57%

Nano-filtration Apparatus.

SARA analysis was performed according to ASTM D2007and ASTM D33279.

SARA Analysis

4

Zhao, B. and Shaw, J.M., Energy & Fuels 2007, 21, (5), 2795-2804.


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Param eters Frequency (shear rate): 0.1 to 100 Hz. Temperature: 25, 30, 50, 75 & 100C.

Parallel Plate

Rheometer

Rheological Measurements

A Bohlin Gemini Malvern nano-rheometer was used.

Parallel plate geometry used (for

most samples) Double gap cylinder used (for very

low viscosity samples, e.g. maltene)

Bohlin Gemini Rheometer.

Rheometer

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Results and Analysis

150 200 250 300 3500

20

40

60

80

100

AB bitumenMaya crude

T o t a l

S o l

i d ( w t . % )

Temperature (K)

AB Samples ABP10 ABP20 ABP50 AB ABR200ABR1

0

Asph.altenes

(C5) 5.3 10.4 13.6 18.6 50.0 57.2

Maya Samaples MP5 MP10 MP20 MP50Maya

crudeMR5

Asphaltenes (C5) 1.5 6.2 8.1 9.4 15.7 46.7

Temp, K 149 170 200 230 250 270 290 310 320 325

Maya Maltene 1.00 0.96 0.81 0.59 0.44 0.30 0.17 0.06 0.02 0

AB Maltene 1.00 1.00 1.00 0.8 0.63 0.46 0.28 0.11 0 0

Table 1 : Solid Content of Maltenes.

Table 2, 3 : Solid Asphaltenes (SARA Analysis).

Fig. Total solid (wt.%) for

AB and Maya.

Phase Behavior of AB and Maya Samples

Total Solid = Solid from maltene + solid asphaltenes

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Fulem, Becerra, Hasan, Zhao, and Shaw, Fluid

Phase Equilibria 272 (2008) 32-41


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Both Maya crude and Athabasca bitumen exhibit Newtonian plateaus at low shearrate over the entire temperature interval evaluated.

For Athabasca bitumen at 298 K the Newtonian plateau is evident only at < 0.01 Hz.

Maya Crude oilthabasca Bitumen (AB)

Complex Viscosity of AB and Maya Samples

0.1 1 10 1000.1

1

10

100

1000

(a)

C o m p l e

x V i s c o s i

t y ( P a . s

)

Frequency (Hz)

298 K303 K323 K348 K373 K

0.1 1 10

0.01

0.1

1(c)

C o m p l e x

V i s c o s i

t y ( P a . s

)

Frequency (Hz)

298 K303 K323 K348 K373 K

1E-4 1E-3 0.01 0.1 1 10800

1000

1200

1400

1600

1800

2000 (b)

C o m p l e x

V i s c o s i

t y ( P a . s

)

Frequency (Hz)

Low shear rate experimentHigh shear rate experiment

AB at Low shear rate

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The viscosity values in this study arehigher except for values obtained by Wardand Clark(Abasand), Charbonnier et al.(for some locations) and Camp (Abasand).

This is because zero shear viscosities areby definition the highest values

Also because our bitumen sample is a

partially processed product from anaphtha recovery unit at Syncrude. Someof the more volatile constituents of thebitumen have been removed.

Athabasca Bitumen

Comparison of our data with those n iterature

300 350 400 450 50010-3

10-2

10-1

100

101

102

103

104

105

106

107

This work, zero shear rateBriggs (1978); RBV; = (14 to 225) s -1 (Ref. 18, 19)Briggs (1978); CCV; = (12 to 1400) s -1 (Ref. 18, 19)Camp (1974); n/s ; is n/s (Ref. 20)Charbonnier et al. (1969); n/s ; is n/s (Ref. 21)Dealy (1979); MS; = 1 s -1 (Ref. 22)Ward, Clark (1950), from different locations;CapV; is n/s (Ref. 23)Flock, Boogmans (1976); CCV;

= (13 to 2300) s -1 (Ref. 24)Jackobs (1978); CCV; is n/s (Ref. 25)Mehrotra, Svrcek (1985); CCV; is n/s (Ref. 26)

Svrcek et al. (1979); CCV; is n/s (Ref. 27)Robinson et al. (1983); CapV; is n/sSchramm, Kwak (1988); CCV; = 460 s -1

V i s c o s i

t y ( P a

. s )

Temperature (K)

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Athabasca Bitumen Permeates Maya Crude oil Permeates

All permeates exhibit a Newtonian plateau at low frequency.

0.1 1 10 100

0

100

200

300

400

500

600

700 (a)

C o m p l e x

V i s c o s

i t y ( P a . s )

Frequency (Hz)

Asphaltene concentration50 nm = 13.6 wt. %20 nm = 10.4 wt. %10 nm = 5.3 wt. %Extrapolated Solid

Free Maltene = 0 wt. %

0.1 1 100.00

0.25

0.50

0.75

1.00

1.25

1.50 (b)

C o m p l e x

V i s c o s

i t y ( P a . s )

Frequency (Hz)

Asphaltene Concentration50 nm = 9.4 wt.%20 nm = 8.1 wt.%10 nm = 6.2 wt.%5 nm = 1.5 wt.%

Extrapolated SolidFree Maltene = 0 wt.%


Complex Viscosity of Permeates

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Viscosity of Athabasca bitumen samples are about three orders of

magnitude higher compared to Maya crude samples.


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Complex viscosity of retentatesamples from viscous modulusmaster curve.

Viscous modulus of 200 nm retentate

Complex Viscosity of Retentates

0.01 0.1 1 10 1000

100000

200000

300000

400000

500000

600000

(a) Asphaltene Concentration10 nm AB retentate = 57.2 wt.%200 nm AB retentate = 50 wt.%

5 nm Maya retentate = 46.7 wt.%

C o m p l e x v i s c o s

i t y ( P a . s )

Frequency (Hz)

0.01 0.1 1 10 100

100

1000

10000

100000

1000000

(a)

V i s c o u s

M o d u l u s

( P a )

Frequency (Hz)

298 K323 K348 K373 K

1E-7 1E-6 1E-5 1E-4 1E-3 0.01 0.1 1 10 100 100010

100

1000

10000

100000

1000000

1E7

1E8

1E9 (b)0= 8.84 08 Pa.s

V i s c o u s

M o d u l u s (

P a )

aT (rad/s)

298 K, a T = 1323 K, a T = 2E-03348 K, a T = 1E-05373 K, a T = 6E-07

Viscous modulus master curve, 298K

Results and Analysis 10


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Relative Viscosity of Permeates

0 5 10 15 20 25 30 350

2

4

6

8

(a)

298 K323 K348 K373 K

R e l a t

i v e

V i s c o s

i t y

Total Solid (wt.%)

0 5 10 15 20 250

1

2

3

4

(b)

298 K303 K323 K373 K

R e

l a t i v e

V i s c o s i

t y

Total Solid (wt.%)

11

Relative viscosity data for all different temperatures fall on a single linewhen expressed in terms of total solid content.


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The rheological behavior of the nanofiltered samples is consistent with thebehavior of a slurry comprising a Newtonian liquid + non-interacting hard

spheres in the temperature range 298 K to 373 K

Generalized SudduthEquation with [] = 2.5; = -

1.5; and k = 1.29; fits theexperimental data for thenanofiltered samples of bothAthabasca bitumen andMaya crude oil very well.

Relative Viscosity of All Samples

Zero-hear zero-olid relatveviscosites of all samples.

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0 2 4 6 8 10 12 14 160

1

2

3

(b)

R e l a t i v e

V i s c o s i

t y

Asphaltene (wt.%)

298 K303 K323 K373 K

0 5 10 15 200

2

4

6

8

10

(a)

R e l a t

i v e V i s c o s i

t y

Asphaltene (wt.%)

298 K323 K348 K373 K


Zero asphaltene based Relative Viscosity

If expressed in terms of asphaltene wt% instead of total solid wt%, apparenttemperature dependence is evident for Athabasca bitumen related samples.For Maya crude oil related samples the impact is less pronounced because less of the maltene is solid.


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Again, the apparent temperature dependence is significant.These dependences have been wrongly attributed to change of shape of asphalteneaggregates, asphaltene-maltene interaction, or asphaltene self association. Suchmisattributions introduce additional fluid physics and fluid chemistry not needed to

explain the rheological behavior of such fluids.

Maya crude oil permeatesthabasca Bitumen Permeates

Chemically Separated Maltene based Relative Viscosity

0 5 10 15 201

10

100

(b)

298 K303 K323 K

R e

l a t i v e

V i s c o s i

t y

Asphaltene (wt.%)

0 5 10 15 201

10

100

1000

(a)298 K323 K348 K373 K

R e l a t

i v e

V i s c o s i

t y

Asphaltene (wt.%)

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Rheological investigations of hydrocarbon resources must account for theimpacts of solid maltenes as well as for asphaltenes in modeling and

analysis.

Conclusion

Failure to account for solid maltenes in the interpretation of rheologicaldata for these hydrocarbon resources leads to misattributions related to thenature and the importance of the role that asphaltenes play in thedetermination of hydrocarbon resource viscosity.

Nanofiltered Maya Crude and Athabasca bitumen exhibit rheologicalbehaviors consistent with slurries comprising a Newtonian liquid + non-interacting hard spheres in the temperature range 298 K to 373 K, if allsolids present are accounted for.

Composition and/or phase behavior of maltene plays crucial role indetermining bitumen and heavy oil viscosity.

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Acknowledgements

-Thanks to Mildred Becerra, and Bei Zhao

-This research was supported by the Alberta Energy Research Institute, ConocoPhillips Inc., Imperial Oil Resources, Halliburton, Kellogg Brown and Root, NEXEN Inc., Shell Canada, Total, Virtual

Materials Group, NSERC, and the Alberta Ingenuity Fund.

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2009 nano micro structure of bitumen and heavy oil using montreal hasan et al. pdf[1]

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