AIChE_Annual_Meeting_2016_Presentation final

Application of molecular characterization to bituminous crude oil to study

asphaltene precipitation

M. R. Islam, Yifan Hao, Meng Wang,

Toni Kirkes, and Chau-Chyun Chen

November 14, 2016

Department of Chemical Engineering

Texas Tech University

Motivation

December 28, 2016 2

Strongly affects viscosity Scale formation Alter rock permeability Catalyst coking

Petroleum Supply Chain

Asphaltenes are the cholesterol of petroleum fluid

www.safesealsystems.com/nav4/the-crude-oil-delivery-network/

http://chem409group14.wikispaces.com/2.+Asphaltenes

http://www.intechopen.com/source/html/39353/media/image2.jpeg

Interconnected production wells and pipelines

Different sources have different composition

Blending operation of different crudes and products

Flow Assurance Context

http://www.safesealsystems.com/nav4/the-crude-oil-delivery-network/


















Motivation

December 28, 2016 3

High asphaltenes content Huge reserves Low price Dilution to aid transportation

Source: International Energy Agency (IEA) Precipitation Prediction Model

Paraffin content of blend promotes precipitation Compatible blends determination Forecast precipitation condition Comprehensive thermodynamic model for asphaltene solubility

Heavy Oils and Bitumen

Outline

December 28, 2016 4

Molecular structure of asphaltene

Aggregation thermodynamics

Asphaltene precipitation prediction from binary solvents

Molecule based characterization of petroleum feedstock

Precipitation prediction from Athabasca bitumen

Simulation of asphaltene precipitation paradox

Conclusion

Future work

Asphaltene Molecular Structure: Yen-Mullins Model

December 28, 2016 5

Asphaltene Molecule Polycyclic aromatic hydrocarbon(PAH) PAH likely contains heteroatom: N, O, S Peripheral alkane substituents MW ~ 750 Da Nanoaggregate Dipole-dipole attracted PAHs Steric-repelling alkanes (hairy tennis ball) Aggregation number ~ 6

Molecule 1.5 nm

Mullins, O.C., et al., Energy & Fuels, 2012. 26(7): p. 3986-4003.

Nanoaggregate 2.0 nm

Cluster 5.0 nm

Aggregation Thermodynamics for precipitation

December 28, 2016 6

Volume fraction of toluene Volume fraction of toluene

Frac

tio

n o

f as

ph

alte

ne

pre

cip

itat

ion

Crystallization Process Aggregation Process

C5 – C10 C5 – C10

Wang, M., et al., AIChE J., 2016. 62(4): p. 1254-64.

Mannistu, K.D., et al., Energy & Fuels, 1997. 11(3): p. 615-622.

UNIFAC Model

December 28, 2016 7

ethanol toluene

-CH3 -CH2-

-OH

Aromatic –CH=

Aromatic C-CH3

Precipitation Prediction from Binary Solvents: UNIFAC

December 28, 2016 8

Frac

tio

n o

f as

ph

alte

ne

pre

cip

itat

ion

Volume fraction of n-hexane

Wang, M., et al., AIChE J., 2016. 62(4): p. 1254-64.

Mannistu, K.D., et al., Energy & Fuels, 1997. 11(3): p. 615-622.

ln 𝐾agg = −3.7

n-C5 n-C6

n-C8 n-C10

n-C7

i-C5 i-C8

MeOH Acetone

1-hexene

Nitrobenzene t-butylbenzene

Cy-C6 Decalin

Dichloromethane

Volume fraction of toluene

0.0

0.2

0.4

0.6

0.8

1.0

0.0 0.2 0.4 0.6 0.8 1.00.0

0.2

0.4

0.6

0.8

1.0

0.0 0.2 0.4 0.6 0.8 1.0

0.0

0.2

0.4

0.6

0.8

1.0

00.20.40.60.81

Modified NRTL-SAC model

December 28, 2016 9

Four conceptual segments:

Hydrophobic (X)

Polar attractive (Y-)

Polar repulsive (Y+)

Hydrophilic (Z)

n-hexane

DMSO

nitromethane

water

Four conceptual segments:

Hydrophobic (X) – n-hexane

Polar attractive (Y-) – DMSO

Polar repulsive (Y+) –nitromethane

Hydrophilic (Z) – water

X Z

X

Y+

ethanol toluene

Chen and Song, I&ECR (2004); Hao et al., 262S, 2016 AIChE Annual Meeting, San Francisco

ln 𝛾𝐼R = ln 𝛾𝐼

lc = 𝑟𝑚,𝐼 ln Γ𝑚lc − ln Γ𝑚

lc,𝐼

𝑚

𝑚 ∈ {𝑋, 𝑌−, 𝑌+, 𝑍}

ln 𝛾𝐼C = ln𝛾𝐼

SG′ = 1 −𝜙′𝐼𝑥𝐼+ ln𝜙′𝐼𝑥𝐼−1

2𝑍𝑞′𝐼 1 −

𝜙′𝐼𝜃′𝐼+ ln𝜙′𝐼𝜃′𝐼

F-H part S-G correction

Precipitation Prediction from Binary Solvents: NRTL-SAC*

December 28, 2016 10

Frac

tio

n o

f as

ph

alte

ne

pre

cip

itat

ion

Volume fraction of n-hexane Mannistu, K.D., et al., Energy & Fuels, 1997. 11(3): p. 615-622.

ln 𝐾agg = −6.8

Asphaltene Nanoaggregate

𝑋 6.116 2.863

𝑌− 1.346 0

𝑌+ 1.512 0

𝑍 0 0

n-C5 n-C6

n-C8 n-C10

n-C7

i-C5 i-C8

MeOH Acetone

1-hexene

Nitrobenzene t-butylbenzene

Cy-C6 Decalin

Dichloromethane

Volume fraction of toluene

Problem Statement


Extraction of asphaltene from Athabasca bitumen

upon mixing of n-heptane

For bitumen and crude oils, the volume of n-paraffin

at onset precipitation increases with n-paraffin

carbon number and reaches a maximum

Tharanivasan, A., et al., Energy & Fuels, 2009. 23: p. 3971-80.

Wiehe, I., et al., Energy & Fuels, 2005. 19: p. 1261-67.

Real molecule-based molecular characterization*


Initial guess for class mole fraction and segment distribution function parameters, i.e., scale, shape and position

Molecular thermodynamic model Estimate crude assay properties

Experimental assay data

NO

Root-mean-square error

Check convergence

Optimal constituent components and composition Mole fraction for each molecule

𝑦𝑙,𝑚,𝑛 = 𝑦𝑐𝑙𝑎𝑠𝑠 𝑝𝑠𝑒𝑔1 𝑙 𝑝𝑠𝑒𝑔2 𝑚 … 𝑝𝑠𝑒𝑔𝑁 𝑛

YES

HYSYS *Chen and Que. Method of characterizing

chemical composition of crude oil for

petroleum refinery processing.

WO2013106755 A1, 2013.

Segment

Type

Segment Number

Range

0 – 6

0 – 6

–CnH2n+1 n = 0 – 48

Aromatics

Example:

A-5-1-5

Gamma distribution function for segments

𝑝 𝑛 =(𝑛 − 𝐿)𝛼−1𝑒

−𝑛−𝐿𝛽

𝛽𝛼Γ(𝛼)

𝛼 – shape parameter

𝛽 – scale parameter

𝐿 – position parameter

Crude Assay of Athabasca Bitumen


Cold Lake Bitumen Whole Crude Naphtha Distillate Light Gas Oil Heavy Gas Oil Vacuum Gas Oil Vacuum Residue

Initial Temp., °C IBP IBP 266 343 399 454 527 Final Temp., °C FBP 266 343 399 454 527 FBP Yield Yield, mass% 1.807 7.934 9.512 9.027 15.710 56.009 Yield, volume% 2.102 8.872 10.215 9.384 16.151 53.276 Physical Properties API Gravity, °API @ 15°C 8.104 31.330 25.088 18.792 14.004 12.412 1.671 Relative Density @ 15°C 1.014 0.869 0.904 0.941 0.972 0.983 1.063 Absolute Density @ 15°C, kg/m3 1012.680 868.204 902.843 940.699 971.663 982.362 1061.643 Transport Properties Kinematic Viscosity (cSt) @ 30°C 2.990 9.187 Kinematic Viscosity (cSt) @ 40°C 2.410 Kinematic Viscosity (cSt) @ 50°C 2.038 5.016 18.523 96.887 594.111 Kinematic Viscosity (cSt) @ 70°C 1755.65 3.166 8.932 32.049 134.004 Kinematic Viscosity (cSt) @ 80°C 870.71 Kinematic Viscosity (cSt) @ 90°C 471.629 5.162 14.307 45.494 401763.43 Kinematic Viscosity (cSt) @ 100°C 130934.49 Kinematic Viscosity (cSt) @ 110°C 48471.169


Cold Properties Cloud Point, °C -34.16 -35.27 -40.666 Pour Point, °C -65 -59.009 -33.392 -9.759 11.659 Softening Point, °C 77.028 Contaminants Ash Content, wt. % 0.203 Asphaltene Content, wt. % (C5) 18.943 33.376 Asphaltene Content, wt. % (C7) 10.960 19.692 Ion Content, wt. ppm 7.992 14.750 Micro Carbon Residue, wt. % 14.099 <0.01 0.034 0.491 24.949 Nickel Content, wt. ppm 85.355 152.894 Nitrogen Content, wt. ppm 4431.074 32.424 141.639 608.238 1384.647 2536.736 6822.796 Sulfur Content, wt. % 4.995 0.946 1.788 2.859 3.571 3.897 6.572 Vanadium Content, wt. ppm 222.229 398.654 Burning Characteristic Smoke Point, mm 20.770 Cetane Index 39.012 Others Aniline Point 55.890 53.654 120.603 49.580 55.772

Total Acid Number, mg KOH/g 2.330 0.500 1.271 3.115 3.103 3.485 0.964 Watson K Factor 11.300 11.286 11.245 11.175 11.288


PNA Composition Paraffins, vol. % 5.522 4.883 Naphthenes, vol. % 79.689 60.455 Aromatics, vol. % 14.789 34.662 Distillation Data Distillation, wt. % 0 197.700 139.300 199.000 264.000 318.800 361.000 -- 5 260.141 184.740 237.835 305.449 357.462 406.157 543.575 10 294.261 194.619 250.839 316.044 368.737 417.960 565.995 15 325.326 203.193 261.741 325.175 378.454 428.308 587.738 20 354.000 210.627 270.844 333.029 386.807 437.375 608.563 25 380.947 217.088 278.454 339.793 393.993 445.337 628.229 30 406.830 222.743 284.872 345.653 400.206 452.369 646.494 40 458.061 232.299 295.352 355.409 410.497 464.344 677.855 50 513.004 240.625 304.712 363.789 419.242 474.702 715.100 60 576.972 249.051 315.382 372.286 428.004 484.844 -- 70 655.274 258.908 329.600 382.393 438.345 496.171 -- 80 -- 271.527 343.100 395.604 451.829 510.085 -- 90 -- 288.239 361.300 413.410 470.018 527.988 -- 95 -- 298.546 376.900 424.503 481.365 538.873 -- 100 -- 445.300 438.200 605.300 586.600 637.300 --

Source: Alberta Department of Energy, Canada

Crude Assay of Athabasca Bitumen



Initial Temp., °C IBP IBP 266 343 399 454 527 Final Temp., °C FBP 266 343 399 454 527 FBP Yield Yield, mass% 1.807 7.934 9.512 9.027 15.710 56.009 Yield, volume% 2.102 8.872 10.215 9.384 16.151 53.276 Physical Properties API Gravity, °API @ 15°C 8.104 31.330 25.088 18.792 14.004 12.412 1.671 Relative Density @ 15°C 1.014 0.869 0.904 0.941 0.972 0.983 1.063 Absolute Density @ 15°C, kg/m3 1012.680 868.204 902.843 940.699 971.663 982.362 1061.643 Transport Properties

Kinematic Viscosity (cSt) @ 30°C 2353 2.990 9.187 35.06 104.38 265.27 1795071

Kinematic Viscosity (cSt) @ 40°C 1299 2.410 6.455 25.65 72.33 168.41 668218 Kinematic Viscosity (cSt) @ 50°C 756 2.038 5.016 18.523 96.887 594.11 668219 Kinematic Viscosity (cSt) @ 70°C 1755.651 1.409 3.166 8.932 32.049 134.00 52736

Kinematic Viscosity (cSt) @ 80°C 870.717 1.242 3.117 9.716 23.142 39.97 25494





Cold Properties Cloud Point, °C -51.4 -34.16 -35.27 -40.666 -45.90 -51.67 -65.47 Pour Point, °C 31.3 -65 -59.009 -33.392 -9.759 11.659 72.9 Softening Point, °C 77.028 Contaminants Ash Content, wt. % 0.203 Asphaltene Content, wt. % (C5) 18.943 33.376 Asphaltene Content, wt. % (C7) 10.960 19.692 Iron Content, wt. ppm 7.992 14.750 Micro Carbon Residue, wt. % 14.099 <0.01 0.034 0.491 24.949 Nickel Content, wt. ppm 85.355 152.894 Nitrogen Content, wt. ppm 4431.074 32.424 141.639 608.238 1384.647 2536.736 6822.796 Sulfur Content, wt. % 4.995 0.946 1.788 2.859 3.571 3.897 6.572 Vanadium Content, wt. ppm 222.229 398.654 Burning Characteristic

Smoke Point, mm 4.26 20.770 8.24 4.69 1.93 1.38 15.20

Cetane Index 47 28.5 39.012 41 43 48 51 Others Aniline Point 67.21 55.890 53.654 120.603 49.580 55.772 72.94

Total Acid Number, mg KOH/g 2.330 0.500 1.271 3.115 3.103 3.485 0.964 Watson K Factor 11.13 11.300 11.286 11.245 11.175 11.288 11.19


PNA Composition

Paraffins, vol. % 0.70 5.522 4.883 0.49 0 0 0

Naphthenes, vol. % 23.73 79.689 60.455 46.24 45.70 36.74 5.78

Aromatics, vol. % 75.57 14.789 34.662 53.26 54.30 63.26 94.22 Distillation Data Distillation, wt. % 0 197.700 139.300 199.000 264.000 318.800 361.000 536.92 5 260.141 184.740 237.835 305.449 357.462 406.157 543.575 10 294.261 194.619 250.839 316.044 368.737 417.960 565.995 15 325.326 203.193 261.741 325.175 378.454 428.308 587.738 20 354.000 210.627 270.844 333.029 386.807 437.375 608.563 25 380.947 217.088 278.454 339.793 393.993 445.337 628.229 30 406.830 222.743 284.872 345.653 400.206 452.369 646.494 40 458.061 232.299 295.352 355.409 410.497 464.344 677.855 50 513.004 240.625 304.712 363.789 419.242 474.702 715.100

60 576.972 249.051 315.382 372.286 428.004 484.844 653.46

70 655.274 258.908 329.600 382.393 438.345 496.171 687.97

80 701.22 271.527 343.100 395.604 451.829 510.085 756.57

90 816.68 288.239 361.300 413.410 470.018 527.988 788.45

95 827.94 298.546 376.900 424.503 481.365 538.873 795.60 100 -- 445.300 438.200 605.300 586.600 637.300 --

Athabasca Bitumen Composition


Paraffins

Naphthenes

Thiophenes

Quinolenes

Aromatics

Whole Crude (wt%)

Malten composition

Asphaltene composition

Molecule Distribution of Malten

9

357

261 255

510 Class 𝐌𝐖 Mole%

Paraffins 244 0.96

Naphthenes 368 24.25

Aromatics 400 40.67

Thiophens 376 27.92

Quinolenes 614 6.20

Malten Asphaltene

𝐌𝐖 374 539

Mole% 85.4 14.6

Mass% 80.2 19.8

R 16.00 21.61

Q 11.45 14.82

83%

5% 12% 1%

22%

41%

26% 10% 1%

29% 33%

32% 5%

Asphaltene Solubility in Athabasca Bitumen


SP

OP

FP

Aggregation Thermodynamics and Input Parameters


ln𝐾agg = −3.64

Asphaltene Nanoaggregate Malten

𝑋 6.116 2.863 3.0

𝑌− 1.346 0 0

𝑌+ 1.512 0 2.86

𝑍 0 0 0

𝑅 21.61 34.17 16.00

𝑄 14.82 27.62 11.45

ln 𝛾𝐼R = ln 𝛾𝐼

lc = 𝑟𝑚,𝐼 ln Γ𝑚lc − ln Γ𝑚

lc,𝐼

𝑚

ln 𝛾𝐼C = ln𝛾𝐼

SG′ = 1 −𝜙′𝐼𝑥𝐼+ ln𝜙′𝐼𝑥𝐼−1

2𝑍𝑞′𝐼 1 −

𝜙′𝐼𝜃′𝐼+ ln𝜙′𝐼𝜃′𝐼

ln𝐾agg = ln 𝑥𝐼agg+ ln

𝛾𝐼agg

𝛾nano∞

Where, 𝑚 ∈ {𝑋, 𝑌−, 𝑌+, 𝑍}

{𝜙𝐼′, 𝜃𝐼′}

Asphaltene Precipitation Problem


Tharanivasan, A., et

al., Energy & Fuels,

2009. 23: p. 3971-80.

Wiehe, I., et al.,

Energy & Fuels,

2005. 19: p.

1261-67.

Conclusion and Future Work


Aggregation thermodynamics successfully predicted asphaltene

solubility in pure and binary solvents

The applicability of thermodynamic framework for asphaltene

precipitation is confirmed for petroleum

Molecule based characterization of petroleum feedstock can be

useful to determine asphaltene precipitation behavior, i.e.,

onset point and yield

In future, different petroleum feedstocks need to be tested to

substantiate current findings

Acknowledgements


AIChE_Annual_Meeting_2016_Presentation final

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