Effect of Crystal Modifiers and Dispersants on Paraffin-Wax Particles in Petroleum Fluids
- Minwei Sun (Reservoir Engineering Research Institute) | Khosrow Naderi (Tenex Technologies) | Abbas Firoozabadi (Reservoir Engineering Research Institute)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- February 2019
- Document Type
- Journal Paper
- 32 - 43
- 2019.Society of Petroleum Engineers
- wax dispersants, crystal modifiers
- 9 in the last 30 days
- 186 since 2007
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Petroleum fluids from shale light-oil and gas/condensate reservoirs generally have a high content of normal paraffins. Paraffin-wax deposition is among the challenges in shale gas and oil production and in offshore flow assurance. Low-dosage chemical additives can be effective in paraffin-wax mitigation because of their high efficiency and economics. These additives are divided into broad categories of crystal modifiers and dispersants with vastly different molecular structures and mechanisms in wax-crystal-particle stabilization and wetting. This investigation focuses on the understanding of the differences in the aggregate size and morphology of chemical additives, and it centers on (1) wax-particle sedimentation from diluted petroleum fluids in vial tests, (2) wax-crystal-particle-size distributions and morphology by dynamic light scattering (DLS) and polarized-light microscopy, and (3) the wetting state from the effect of water. In two of the three petroleum-fluid samples used in this work, there is no visible precipitation at the bottom of the vials at temperatures below the wax-appearance temperature (WAT). The microscopic image of fluids along the length of the tube shows that the wax-particle size and intensity increase from top to bottom. To observe precipitation, we dilute the crude with a hydrocarbon such as n-heptane. The sedimentation of wax is then observed. The petroleum fluids used in this work have very low asphaltene content, and there is no complication from asphaltene precipitation. Our study shows that a small amount of crystal modifier and dispersant can reduce crystal-particle size to the submicron scale, and change the crystal morphology. We investigate the differences in the mechanisms of dispersants and crystal modifiers in bulk. Water, which is often coproduced with petroleum fluids, can increase the effectiveness of dispersants significantly by altering the wetting state of the wax-particle surface. Such enhancement is not found in crystal modifiers. Both additives affect the rheology of petroleum fluids.
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Abdallah, D. J. and Weiss, R. G. 2000. n-Alkanes Gel n-Alkanes (and Many Other Organic Liquids). Langmuir 16 (2): 352–355. https://doi.org/10.1021/la990795r.
Aiyejina, A., Chakrabarti, D. P., Pilgrim, A. et al. 2011. Wax Formation in Oil Pipelines: A Critical Review. International Journal of Multiphase Flow 37 (7): 671–694. https://doi.org/10.1016/j.ijmultiphaseflow.2011.02.007.
Al-Yaari, M. 2011. Paraffin Wax Deposition: Mitigation and Removal Techniques. Presented at the SPE Saudi Arabia Young Professionals Technical Symposium, Dhahran, Arabia, 4–16 March. SPE-155412-MS. https://doi.org/155412-MS.
Ashbaugh, H. S., Radulescu, A., Prud’Homme, R. K. et al. 2002. Interaction of Paraffin Wax Gels With Random Crystalline/Amorphous Hydrocarbon Copolymers. Macromolecules 35 (18): 7044–7053. https://doi.org/10.1021/ma0204047.
Ashbaugh, H. S., Guo, X., Schwahn, D. et al. 2005. Interaction of Paraffin Wax Gels With Ethylene/Vinyl Acetate Co-Polymers. Energy & Fuels 19 (1): 138–144. https://doi.org/10.1021/ef049910i.
Baltzer Hansen, A., Larsen, E., Batsberg Pedersen, W. et al. 1991. Wax Precipitation From North Sea Crude Oils. 3. Precipitation and Dissolution of Wax Studied by Differential Scanning Calorimetry. Energy & Fuels 5 (6): 914–923. https://doi.org/10.1021/ef00030a021.
Becker, J. R. 2000. Oilfield Paraffin Treatments: Hot Oil and Hot Water Compared to Crystal Modifiers. Presented at the SPE Annual Technical Conference and Exhibition, Dallas, 1–4 October. SPE-63123-MS. https://doi.org/10.2118/63123-MS.
Dobbs, J. B. 1999. A Unique Method of Paraffin Control in Production Operations. Presented at the SPE Rocky Mountain Regional Meeting, Gillette, Wyoming, 15–18 May. SPE-55647-MS. https://doi.org/10.2118/55647-MS.
García, M. D. C. 2000. Crude Oil Wax Crystallization. The Effect of Heavy n-Paraffins and Flocculated Asphaltenes. Energy & Fuels 14 (5): 1043–1048. https://doi.org/10.1021/ef0000330.
Guo, X., Adamson, D. H., Tinsley, J. et al. 2004a. Synthesis of Poly (Ethylene-Butene) Random Copolymers With Hydroxylic Grafts and Effect of Polar Groups on Deposition of Wax and Asphaltenes From Crude Oil. Preprints. American Chemical Society. Division of Petroleum Chemistry 49 (3): 272–273.
Guo, X., Pethica, B. A., Huang, J. S. et al. 2004b. Crystallization of Long-Chain n-Paraffins From Solutions and Melts as Observed by Differential Scanning Calorimetry. Macromolecules 37 (15): 5638–5645. https://doi.org/10.1021/ma035848x.
Guo, X., Pethica, B. A., Huang, J. S. et al. 2004c. Crystallization of Mixed Paraffin From Model Waxy Oils and the Influence of Micro-Crystalline Poly (Ethylene-Butene) Random Copolymers. Energy & Fuels 18 (4): 930–937. https://doi.org/10.1021/ef034098p.
Guo, X., Pethica, B. A., Huang, J. S. et al. 2006. Effect of Cooling Rate on Crystallization of Model Waxy Oils With Microcrystalline Poly (Ethylene Butene). Energy & Fuels 20 (1): 250–256. https://doi.org/10.1021/ef050163e.
Halim, N., Ali, S., Nadeem, M. N. et al. 2011. Synthesis of Wax Inhibitor and Assessment of Squeeze Technique Application for Malaysian Waxy Crude. Presented at the SPE Asia Pacific Oil and Gas Conference and Exhibition, Jakarta, 20–22 September. SPE-142288-MS. https://doi.org/10.2118/142288-MS.
Hashmi, S. M., Quintiliano, L., and Firoozaadi, A. 2010. Polymeric Dispersants Delay Sedimentation in Colloidal Asphaltene Suspensions. Langmuir 26 (11): 8021–8029. https://doi.org/10.1021/la9049204.
Huang, Z., Zheng, S., and Fogler, H. S. 2015. Wax Deposition: Experimental Characterizations, Theoretical Modeling, and Field Practices, CRC Press.
Jafari Ansaroudi, H., Vafaie-Sefti, M., Masoudi, S. et al. 2013. Study of the Morphology of Wax Crystals in the Presence of Ethylene-Co-Vinyl Acetate Copolymer. Petroleum Science and Technology 31 (6): 643–651. https://doi.org/10.1080/10916466.2011.632800.
Jafarnia Behbahani, T., Golpasha, R., Akbarina, H. et al. 2008. Effect of Wax Inhibitors on Pour Point and Rheological Properties of Iranian Waxy Crude Oil. Fuel Processing Technology 89 (10): 973–977. https://doi.org/10.1016/fuproc.2008.03.013.
Kok, M. V., Le´toffe´, J.-M., Claudy, P. et al. 1996. Comparison of Wax Appearance Temperatures of Crude Oils by Differential Scanning Calorimetry, Thermomicroscopy, and Viscometry. Fuel 75 (7): 787–790. https://doi.org/10.1016/0016-2361(96)00046-4.
Leube, W., Monkenbusch, M., Schneiders, D. et al. 2000. Wax-Crystal Modification for Fuel Oils by Self-Aggregating Partially Crystallizable Hydrocarbon Block Copolymers. Energy & Fuels 14 (2): 419–430. https://doi.org/10.1021/ef9901544.
Li, L., Guo, X., Adamson, D. H. et al. 2010. Flow Improvement of Waxy Oils by Modulating Long-Chain Paraffin Crystallization With Comb Polymers: An Observation by X-Ray Diffraction. Industrial & Engineering Chemistry Research 50 (1): 316–321. https://doi.org/10.1021/ie101575w.
Li, L., Xu, J., Tinsley, J. et al. 2012. Improvement of Oil Flowability by Assembly of Comb-Type Copolymers With Paraffin and Asphaltene. AIChE Journal 58 (7): 2254–2261. https://doi.org/10.1002/aic.12729.
Machado, A. L., Lucas, E. F., and Gonza´lez, G. 2001. Poly (Ethylene-Co-Vinyl Acetate) (EVA) as Wax Inhibitor of a Brazilian Crude Oil: Oil Viscosity, Pour Point and Phase Behavior of Organic Solutions. Journal of Petroleum Science and Engineering 32 (2–4): 159–165. https://doi.org/10.1016/S0920-4105(01)00158-9.
Machado, A. L. and Lucas, E. F. 2002. Influence of Ethylene-Co-Vinyl Acetate Copolymers on the Flow Properties of Wax Synthetic Systems. Journal of Applied Polymer Science 85 (6): 1337–1348. https://doi.org/10.1002/app.10761.
Mansure, A. J. and, Barker, K. M. 1992. Insights Into Good Hot Oiling Practices. Albuquerque, New Mexico: Sandia National Laboratories.
Marie, E., Chevalier, Y., Eydoux, F. et al. 2005. Control of n-Alkanes Crystallization by Ethylene–Vinyl Acetate Copolymers. Journal of Colloid and Interface Science 290 (2): 406–418. https://doi.org/10.1016/j.jcis.2005.04.054.
Monkenbusch, M., Schneiders, D., Richter, D. et al. 2000. Aggregation Behaviour of PE–PEP Copolymers and the Winterization of Diesel Fuel. Physica B: Condensed Matter 276: 941–943. https://doi.org/10.1016/S0921-4526(99)01681-6.
Pedersen, K. S. and Rønningsen, H. P. 2003. Influence of Wax Inhibitors on Wax Appearance Temperature, Pour Point, and Viscosity of Waxy Crude Oils. Energy & Fuels 17 (2): 321–328. https://doi.org/10.1021/ef020142+.
Petinelli, J. 1979. Effect of Vinyl Ethylene Acetate Coplymers on the Nucleation and Growth-Kinetics of n-Paraffin in a Hydrocarbon Medium. Revnue de L Institut Francais du Petrole 34 (5): 791–811.
Radulescu, A., Schwahn, D., Richter, D. et al. 2003. Co-Crystallization of Poly (Ethylene-Butene) Copolymers and Paraffin Molecules in Decane Studied With Small-Angle Neutron Scattering. Journal of Applied Crystallography 36 (4): 995–999. https://doi.org/10.1107/S0021889803008525.
Radulescu, A., Schwahn, D., Monkenbusch, M. et al. 2004. Structural Study of the Influence of Partially Crystalline Poly (Ethylene Butene) Random Copolymers on Paraffin Crystallization in Dilute Solutions. Journal of Polymer Science Part B: Polymer Physics 42 (17): 3113–3132. https://doi.org/10.1002/polb.20185.
Radulescu, A., Schwahn, D., Stellbrink, J. et al. 2006. Wax Crystallization From Solution in Hierarchical Morphology Templated by Random Poly (Ethylene-Co-Butene) Self-Assemblies. Macromolecules 39 (18): 6142–6151. https://doi.org/10.1021/ma061104i.
Radulescu, A., Fetters, L. J., and Richter, D. 2008. Polymer-Driven Wax Crystal Control Using Partially Crystalline Polymeric Materials. Adv. Polym. Sci. 210 (1): 1–100. https://doi.org/10.1007/12_2007_124.
Radulescu, A., Richter, D., and Fetters, L. J. 2012. Tailored Polymer Additives for Wax (Paraffin) Crystal Control, INTECH Open Access Publisher.
Richter, D., Schneiders, D., Monkenbusch, M. et al. 1997. Polymer Aggregates With Crystalline Cores: The System Polyethylene-Poly (Ethylenepropylene). Macromolecules 30 (4): 1053–1068. https://doi.org/10.1021/ma961039k11.
Sarica, C. and Panacharoensawad, E. 2012. Review of Paraffin Deposition Research Under Multiphase Flow Conditions. Energy & Fuels 26 (7): 3968–3978. https://doi.org/10.1021/ef300164q.
Schwahn, D., Richter, D., Lin, M. et al. 2002. Cocrystallization of a Poly (Ethylene-Butene) Random Copolymer With C24 in n-Decane. Macromolecules 35 (9): 3762–3768. https://doi.org/10.1021/ma0120456.
Singh, P., Fogler, H. S., and Nagarajan, N. 1999. Prediction of the Wax Content of the Incipient Wax-Oil Gel in a Pipeline: An Application of the Controlled-Stress Rheometer. Journal of Rheology 43 (6): 1437–1459. https://doi.org/10.1122/1.551054.
Singhal, H., Sahai, G., Pundeer, G. et al. 1991. Designing and Selecting Wax Crystal Modifier for Optimum Field Performance Based on Crude Oil Composition. Presented at the SPE Annual Technical Conference and Exhibition, Dallas, 6–9 October. SPE-22784-MS. https://doi.org/10.2118/22784-MS.
Son, A., Graugnard, R., and Chai, B. 1993. The Effect of Structure on Performance of Maleic Anhydride Copolymers as Flow Improvers of Paraffinic Crude Oil. Presented at the SPE International Symposium on Oilfield Chemistry, New Orleans, 2–5 March. SPE-25186-MS. https://doi.org/10.2118/25186-MS.
Swanson, T., Petrie, M., and Sifferman, T. 2005. The Successful Use of Both Kinetic Hydrate and Paraffin Inhibitors Together in a Deepwater Pipeline With a High Water Cut in the Gulf of Mexico. Presented at the SPE International Symposium on Oilfield Chemistry, The Woodlands, Texas, 2–4 February. SPE-93158-MS. https://doi.org/10.2118/93158-MS.
Tinsley, J. F., Prud’homme, R. K., Guo, X. et al. 2007. Novel Laboratory Cell for Fundamental Studies of the Effect of Polymer Additives on Wax Deposition From Model Crude Oils. Energy & Fuels 21 (3): 1301–1308. https://doi.org/10.1021/ef060446m.
Wei, B. 2015. Recent Advances on Mitigating Wax Problem Using Polymeric Wax Modifier. Journal of Petroleum Exploration and Production 5 (4): 391–401. https://doi.org/10.1007/s13202-014-0146-6.
Woo, G., Garbis, S., and Gray, T. 1984. Long-Term Control of Paraffin Deposition. Presented at the SPE Annual Technical Conference and Exhibition, Houston, 16–19 September. SPE-13126-MS. https://doi.org/10.2118/13126-MS.
Xu, J., Zhang, X., Sun, J. et al. 2009. How Comb-Type Poly (Maleic Acid Alkylamide-Co-a-Olefin) Assemble in Waxy Oils and Improve Flowing Ability. Asia-Pacific Journal of Chemical Engineering 4 (5): 551–556.
Xu, J., Xing, S., Qian, H. et al. 2013. Effect of Polar/Nonpolar Groups in Comb-Type Copolymers on Cold Flowability and Paraffin Crystallization of Waxy Oils. Fuel 103: 600–605. https://doi.org/10.1016/j.fuel.2012.06.027.
Yi, S. and Zhang, J. 2011. Relationship Between Waxy Crude Oil Composition and Change in the Morphology and Structure of Wax Crystals Induced by Pour-Point-Depressant Beneficiation. Energy & Fuels 25 (4): 1686–1696. https://doi.org/10.1021/ef200059p.