Asphaltene Precipitation in Paraffinic Froth Treatment: Effects of

Nov 28, 2017 - ... Natural Resources Canada , 1 Oil Patch Drive, Devon , Alberta T9G ... A general correlation was obtained between the asphaltene con...
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Asphaltene Precipitation in Paraffinic Froth Treatment – Effect of Solvent and Temperature Yuming Xu Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b03013 • Publication Date (Web): 28 Nov 2017 Downloaded from http://pubs.acs.org on December 1, 2017

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Asphaltene Precipitation in Paraffinic Froth Treatment – Effects of Solvent and Temperature Yuming Xu Natural Resources Canada, CanmetENERGY 1 Oil Patch Drive, Devon, Alberta, T9G 1A8 [email protected] Abstract In surface-mined oil sands operations bitumen is extracted from oil sand ore using a warm water extraction process that produces bitumen froth typically containing 60 wt% bitumen, 30 wt% water, and 10 wt% mineral solids. The bitumen froth is then cleaned in a froth treatment process in which the froth is diluted with solvent to enhance the separation of bitumen from water and solids. In paraffinic solvent froth treatment, light alkanes such as pentane or hexane are used as solvent, leading to precipitation of some of the asphaltenes in the bitumen. The precipitated asphaltenes form agglomerates with the solids and water and these agglomerates quickly settle, producing very clean diluted bitumen. In order to precipitate the required amount of asphaltenes, the solvent-tobitumen ratio used in commercial operations is typically high. In the present work we investigated asphaltene precipitation using other solvents such as butane, neopentane, and carbon dioxide at different temperatures. It was found that the solvent-to-bitumen mass ratio could be reduced significantly by using these solvents or combining them with a more commonly used solvent. The effect of the solvent on asphaltene precipitation can be explained in terms of the solubility parameters of the solvent. A general correlation was obtained between the asphaltene content in bitumen product and the solubility parameters of the solvent.

Keywords

Asphaltene precipitation; Froth treatment; Solubility parameters;

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2 1.

Introduction

Mined oil sand ore, typically containing about 8−12 wt% bitumen, is processed using a warm water extraction process (1). In this process the mined oil sand is mixed with hot water and the resulting slurry is pumped through a pipeline. During this hydrotransport the oil sand is conditioned, that is, the bitumen releases from the sand matrix as droplets, and these droplets engulf air bubbles. When the conditioned slurry enters the primary separation vessel, the bitumen-air droplets float to the top of the vessel to form the product called bitumen froth. Bitumen froth is a mixture of bitumen, water, and mineral solids with a typical composition of 60 wt% bitumen, 10 wt% mineral solids, and 30 wt% water. Water and mineral solids are removed in the subsequent froth treatment step in order to produce a clean bitumen product.

Since bitumen is viscous and the density difference between bitumen and water is small, the froth has to be diluted with an organic solvent to enhance the separation of the bitumen from the water and solids. There are two different froth treatment processes depending on the type of solvent used: traditional naphtha-based froth treatment (NFT) and the newer paraffinic solvent−based froth treatment (PFT). In NFT, naphtha is used to dilute the froth, after which the water and solids are separated from the diluted bitumen by gravity settling or under centrifugal force. The final diluted bitumen product still contains emulsified water (1−2 wt%) and mineral solids such as clay ( iso-pentane > n-pentane. Neopentane has an extremely high ability to precipitate asphaltenes. 2. Froth treatment tests using CO2 demonstrate that CO2 has a strong ability to precipitate asphaltenes when used in combination with paraffinic solvent; the effect of a given mass of CO2 is equivalent to that of about two unit masses of npentane. 3. The use of non-traditional solvents, such as neopentane or CO2 would significantly reduce the size requirement for the settler used in froth treatment plants and the required volume of solvent.

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26 4. Asphaltene precipitation by n-pentane, iso-pentane, and neopentane is slightly temperature dependent. The asphaltene content remaining in the bitumen increases with increasing temperature until reaching a maximum at around 75100 °C. 5. The effects of the solvent type and solvent concentration on asphaltene precipitation can be explained by the solubility parameters. The results illustrate that the asphaltene content in bitumen product is correlated with the solubility parameters of the effective solvent (solvent plus maltenes). A single curve fits all the solvents tested in this study, at various concentrations. This general curve can serve the oil sands industry as a guide for solvent selection in order to precipitate given percentages of asphaltenes. 5.

Acknowledgements

The author would like to thank Jianmin Pang, Surjit Thind, and Derek Chao for their assistance in experimental measurements, and Dr. Merouane Khammar for his assistance in providing the solubility parameter data for CO2. Financial support from the Canadian government’s interdepartmental Program of Energy Research and Development (PERD) is acknowledged.

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27 6. References 1) Masliyah, J.H.; Czarnecki, J.; Xu, Z. Handbook on theory and practice of bitumen recovery from Athabasca oil sands, Vol. I: Theoretical basis. Kingsley Knowledge Publishing, Alberta, Canada, 2011. 2) Rao F.; Liu, Q. Froth treatment in Athabasca oil sands bitumen recovery process: a review. Energy & Fuels 2013, 27, 7199-7208. 3) Long, Y.; Dabros, T.; Hamza. H. Selective solvent deasphalting for heavy oil emulsion treatment. Asphaltenes, Heavy Oils, and Petroleomics, edited O.C Mullins et al., Springer, 2007, pp 511-547. 4) Long, Y.; Dabros, T.; Hamza, H.; Fuel 2002, 81, 1945−1952. 5) Zawala J., T. Dabros, H.A. Hamza, Settling Properties of Aggregates in Paraffinic Froth Treatment, Energy & Fuels, 2012, 26 5775-5781. 6) Speight, J. G. The chemistry and Technology of Petroleum; 4th Ed, Boca Raton, FL:CRC Press, 2006 7) Alshareef AH, Scherer A, Tan X, Azyat K, Stryker JM, Tykwinski RR, et al. Formation of archipelago structures during thermal cracking implicates a chemical mechanism for the formation of petroleum asphaltenes. Energy & Fuels, 2011, 25 2130–6. 8) Acevedo S, Castro A, Negrin JG, Fernandez A, Escobar G, Piscitelli V. Relations between asphaltene structures and their physical and chemical properties: The rosary-type structure. Energy & Fuels 2007, 21 2165–75. 9) Strausz OP, Mojelsky TW, Lown EM, Kowalewski I, Behar F. Structural features of Boscan and Duri asphaltenes. Energy & Fuels 1999,13 228–47. 10) Strausz OP, MojelskyTW, Faraji F, Lown E.M., Peng P. Additional structural details on Athabasca asphaltene and their ramifications. Energy & Fuels, 1999, 13 207–27. 11) Strausz OP, Peng P, Murgich J. About the colloidal nature of asphaltenes and the mw of covalent monomeric units. Energy & Fuels 2002, 16 809–22. 12) Sabbah H, Morrow AL, Pomerantz AE, Zare RN. Evidence for island structures as the dominant architecture of asphaltenes. Energy & Fuels 2011, 25, 1597–604. 13) Groenzin H, Mullins OC. Molecular size and structure of asphaltenes from various sources. Energy & Fuels 2000, 14, 677–84. 14) Sabbah H, Morrow AL, Pomerantz AE, Zare RN. Evidence for island structures as the dominant architecture of asphaltenes. Energy & Fuels 2011, 25, 1597–604. 15) Ruiz-Morales Y, Mullins OC. Polycyclic aromatic hydrocarbons of asphaltenes analyzed by molecular orbital calculations with optical spectroscopy. Energy & Fuels 2007, 21, 256–65. 16) Dickie, J.P, Yen, T.F., Macrostructures of asphaltic fractions by various instrumental methods, Anal. Chem, 1967, 39, 1847- 1852 17) Mullins OC. The modified Yen model. Energy & Fuels 2010, 24, 2179–207. 18) Mullins OC, Sabbah H, Eyssautier J, Pomerantz AE, Barré L, Andrews AB, et al. Advances in asphaltene science and the Yen-Mullins model. Energy & Fuels 2012, 26, 3986–4003.

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Page 28 of 30

28 19) Hirschberg, A.; deJong, L.N.J.; Schipper, B.A.; Meijer, J.G. Influence of temperature and pressure on asphaltene flocculation, Soc. Pet. Eng. J. 1984, 24 (3) 283-293 20) Cimino, R.; Correra, S.; Del Bianco, A.; Lockhart, T.P. In Asphaltenes : Fundamentals and Applications; Sheu, E. Y., Mullins, O.C., Eds.; Plenum Press: New Your, 1995; pp 97-130 21) Anderson, S.I; Speight J.G. Thermodynamic models for asphaltene solubility and precipitation. J. Petro. Sci. Eng. 1999, 22, 53-66 22) Verdier, S.; Carrier, H.; Andersen, S. I.; Daridon, J.-L. Study of pressure and temperature effects on asphaltene stability in presence of CO2. Energy & Fuels 2006, 20, 1584–1590. 23) da Silva NAE, Oliveira VRD, Costa GMN. Modeling and simulation of asphaltene precipitation by normal pressure depletion. J Pet Sci Eng 2013,109, 123–32. 24) H.W. Yarranton, J.H. Masliyah, Molar mass distribution and solubility modeling of asphaltenes, AIChE J. 1996, 42 3533–3543 25) Alboudwarej H, Akbarzadeh K, Beck J, SvrcekWY, Yarranton HW. Regular solution model for asphaltene precipitation from bitumens and solvents. AIChE J 2003, 49, 2948–56. 26) Akbarzadeh K, Dhillon A, Svrcek WY, Yarranton HW. Methodology for the characterization and modeling of asphaltene precipitation from heavy oils diluted with n-alkanes. Energy & Fuels 2004,18, 1434–1441. 27) Akbarzadeh K, Alboudwarej H, Svrcek WY, Yarranton HW. A generalized regular solution model for asphaltene precipitation from n-alkane diluted heavy oils and bitumens. Fluid Phase Equilib. 2005, 232, 159–170. 28) Mofidi AM, Edalat M. A simplified thermodynamic modelling procedure for predicting asphaltene precipitation. Fuel, 2006, 85, 2616–2621. 29) Pazuki GR, Nikookar M. A modified Flory-Huggins model for prediction of asphaltenes precipitation in crude oil. Fuel 2006, 85, 1083–1086. 30) Mohammadi AH, Richon D. A monodisperse thermodynamic model for estimating asphaltene precipitation. AIChE J., 2007, 53, 2940–2947. 31) Wiehe, I. A.; Yarranton, H. W.; Akbarzadeh, K.; Rahimi, P.M.; Teclemariam, A. The paradox of asphaltene precipitation with normal paraffins. Energy & Fuels, 2005, 19, 1261-1267 32) Nellensteyn FJ. Relation of the micelle to the medium in asphalt. Inst Pet Technol 1928, 14, 134–138. 33) Pfeiffer JP, Saal RNJ. Asphaltic bitumen as colloid system. J Phys Chem. 1940, 44,139–149. 34) Wiehe, I.A., Process chemistry of Petroleum Macromolecules, CRC Press: Boca Raton, FL, 2008 35) Eyssautier, J.; Levitz, P.; Espinat, D.; Jestin, J.; Gummel, J.; Grillo, I.; Barre, L. Insight into asphaltene nanoaggregate structure inferred by small angle neutron and X-ray scattering. J. Phys. Chem. B 2011, 115, 6827−6837. 36) Sheu, E. Y. Small angle scattering and asphaltenes. J. Phys.:Condens. Matter 2006, 18, S2485−S2498.

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29 37) Gawrys, K. L.; Kilpatrick, P. K. Asphaltenic aggregates are polydisperse oblate cylinders. J. Colloid Interface Sci. 2005, 288, 325−334. 38) Ruckenstein E, Nagarajan R. Aggregation of amphiphiles in nonaqueous media. J Phys Chem 1980, 84,1349–58. 39) Smith GN, Brown P, Rogers SE, Eastoe J. Evidence for a criticalmicelle concentration of surfactants in hydrocarbon solvents. Langmuir 2013, 29, 3252– 3258. 40) Agrawala, M., Yarranton, H. W., Asphaltene association model analogous to linear polymerization, Ind. Eng. Chem. Res., 2001, 40, 4664-4672 41) Leontaritis KJ, Mansoori GA. Asphaltene flocculation during oil production and processing: A thermodynamic colloidal model. San Antonio, Texas: SPE International Symposium on Oilfield Chemistry; 1987. 42) Andreatta G, Bostrom N, Mullins OC. High-Q ultrasonic determination of the critical nanoaggregate concentration of asphaltenes and the critical micelle concentration of standard surfactants. Langmuir 2005; 21:2728–36. 43) Fenistein, D.; Barre, L. Experimental measurement of the mass distribution of petroleum asphaltene aggregates using ultracentrifugation and small-angle X-ray scattering. Fuel 2001, 80, 283−287. 44) Goual L, Sedghi M, Zeng H, Mostowfi F, McFarlane R, Mullins OC. On the formation and properties of asphaltene nanoaggregates and clusters by DCconductivity and centrifugation. Fuel 2011, 90, 2480–2490. 45) Marques, J.; Merdrignac, I.; Baudot, A.; Barre, L.; Guillaume, D.; Espinat, D.; Brunet, S. Asphaltenes size polydispersity reduction by nano- and ultrafiltration separation methods-Comparison with the flocculation method. Oil Gas Sci. Technol. 2008, 63, 139−149. 46) Zhao, B.; Shaw, J. M. Composition and size distribution of coherent nanostructures in Athabasca bitumen and Maya crude oil. Energy Fuels 2007, 21, 2795−2804. 47) Acevedo, S.; Castro, A.; Vasquez, E.; Marcano, F.; Ranaudo, M. A. Investigation of physical chemistry properties of asphaltenes using solubility parameters of asphaltenes and their fractions A1 and A2. Energy Fuels 2010, 24, 5921−5933. 48) Spiecker, P. M.; Gawrys, K.L.; Kilpatrick, P. K. Aggregation and solubility behavior of asphaltenes and their subfractions. J. Colloid Interface Sci. 2003, 267, 178−193. 49) Wu Q, Seifert DJ, Pomerantz AE, Mullins OC, Zare RN. Constant asphaltene molecular and nanoaggregate mass in a gravitationally segregated reservoir. Energy & Fuels 2014, 28, 475–482. 50) Gawrys, K.L., Blankenship, G. A., Kilpatrick, P. K. On the distribution of Chemical Properties and Aggregation of Solubility Fractions in Asphaltenes, Energy & Fuels, 2006, 20, 705-714. 51) Majumdar RD, Gerken M, Mikula R, Hazendonk P. Validation of the Yen−Mullins model of Athabasca oil-sands asphaltenes using solution-state 1H NMR relaxation and 2D HSQC spectroscopy. Energy Fuel 2013; 27(11):6528–37. 52) Subramanian, S., Simon, S., Sjoblom, J. Asphaltene Precipitation Models: A review, J. Disp. Sci. Tech., 2016, 37, 1027-1049.

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Page 30 of 30

30 53) Barton, A.F.M., Handbook of Solubility Parameters and other Cohesion Parameters, CRC Press, 1983 54) Wang, J. X, and Buckley, J.S. A two-component solubility model of the onset of asphaltene flocculation in crude oils. Energy & Fuels 2001, 15, 1004-1012. 55) Nikooyeh, K., Shaw, J. M, On the Applicability of the Regular Solution Theory to Asphaltene + Diluent Mixtures, Energy & Fuels, 2012, 26, 576-585. 56) Wiehe, I. A., Asphaltene Solubility and Fluid Compatibility, Energy & Fuels, 2012, 26, 4004-4016 57) Xu, Y.; Dabros, T.; Kan, J. Effect of aromatic contaminant in solvent on paraffinic froth treatment. 61st CSChE conference, London, ON, Canada, Oct 2226, 2011. 58) Zhao, Y.; Wei, F. Simultaneous removal of asphaltenes and water from water-inbitumen emulsion I. Fundamental development. Fuel Processing Technology, 2008, 89, 933-940. 59) Idem, R.O, Ibrahim, H.H. Kinetics of CO2-induced asphaltene precipitation from various Saskatchewan crude oils during CO2 miscible flooding. J. Petroleum Science and Engineering 2002, 35, 233–246. 60) Srivastava, R. S.; Huang, S. S. Asphaltene deposition during CO2 flooding: a laboratory assessment. SPE 37468, 1997. 61) Takahashi, S.; Hayashi, Y.; Yazawa, N.; Sarma, H. Characteristics and impact of asphaltene precipitation during CO2sandstone and carbonate cores: An investigative analysis through laboratory tests and compositional simulation, SPE 84895. SPE International Improved Oil Recovery Conference in Asia Pacific , Kuala Lumpur, Malaysia, Oct 20−21, 2003 62) Kalra, H.; Kubota, H.; Robinson, D. B.; Ng, H-J. Equilibrium phase properties of the carbon dioxide-n-heptane system. J. Chem. Eng. Data 1978, 23 (4), 317–321 63) Li, Y.-H.; Dillard, K. H.; Robinson, R. L. Vapor-liquid phase equilibrium for carbon dioxide-n-hexane at 40, 80, and 120 °C. J. Chem. Eng. Data 1981, 26 (1), 53-55. 64) Leu, A.-D.; Robinson, R. L. Equilibrium phase properties of selected carbon dioxide binary systems: n-pentane-carbon dioxide and isopentane-carbon dioxide. J. Chem. Eng. Data 1987, 32 (4), 447-450. 65) Mitchell, D. L; Speight, J.G. Solubility of asphaltenes in hydrocarbon solvents. Fuel 1973, 52, 149-152 66) Williams, L.L.; Rubin, J.B.; Edwards H.W. Calculation of Hansen solubility parameter values for a range of pressure and temperature conditions, including the supercritical fluid region, Ind. Eng. Chem. Res. 2004, 43, 4967-4972 67) Gallant R.W., Yaws, C.L. Physical Properties of Hydrocarbons. Gulf Publishing Company, 1992 68) National Institute of Standards and Technology. NIST Chemistry Webbook, SRD 69; http://webbook.nist.gov/chemistry/fluid/.

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