Based on the theory of non-equilibrium thermodynamics, considering the dynamic effect of molecular diffusion and the change in thermodynamic parameters caused by wax precipitation, the phenomenological relations of different thermodynamic "force" and "flow" interactions were derived. The corresponding thermodynamic model of a waxy crude oil pipeline transportation system was built, and then, the excess entropy production expression was proposed. Furthermore, the stability criterion model of the pipeline transportation system was established on the basis of Lyapounov stability theory. Taking the oil pipeline in Daqing oilfield as an example, based on the four parameters of out-station temperature, out-station pressure, flow rate and water content, the stable and unstable regions of the system were divided, and the formation mechanisms of the two different regions were analyzed. The experimental loop device of wax deposition rate was designed, and then, the wax deposition rate under the four parameters was measured. The results showed that the stable region of the wax deposition rate fluctuation was basically in accordance with the stability region analyzed by the criterion model established in this paper, which proved that the stability criterion model was feasible for analyzing the stability of the waxy crude oil pipeline transportation process.
wax precipitation thermodynamic model excess entropy production stability criterion model loop device for wax deposition rate
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This study is financially supported by the National Natural Science Foundation of China (51534004) and the Northeast Petroleum University “National Fund” Cultivation Fund (2017PYZL-07).
Rui Z, Wang X, Zhang Z, et al. A realistic and integrated model for evaluating oil sands development with Steam Assisted Gravity Drainage technology in Canada. Applied Energy, 2018, 213: 76–91.CrossRefGoogle Scholar
Cheng QL, Gan YF, Su WK, et al. Research on exergy flow composition and exergy loss mechanisms for waxy crude oil pipeline transport processes. Energies, 2017, 10(12): 1956.CrossRefGoogle Scholar
Yang L, Chen G. Optimal parameters design of oilfield surface pipeline systems using fuzzy models. Information Sciences, 1999, 120(1–4): 13–21.Google Scholar
Xie K, Lu X, Li Q, et al. Analysis of reservoir applicability of hydrophobically associating polymer. SPE Journal, 2016, 21(01): 1–9.CrossRefGoogle Scholar
Pal R. Second law analysis of adiabatic and non-adiabatic pipeline flows of unstable and surfactant-stabilized emulsions. Entropy, 2016, 18(4): 113.ADSCrossRefGoogle Scholar
Røsjorde A, Kjelstrup S, Johannessen E, et al. Minimizing the entropy production in a chemical process for dehydrogenation of propane. Energy, 2007, 32(4): 335–343.CrossRefGoogle Scholar
Manzi J, Vianna R, Bispo H. Direct entropy minimization applied to the production of propylene glycol. Chemical Engineering and Processing: Process Intensification, 2009, 48(1): 470–475.CrossRefGoogle Scholar
Liu Y, Pan C, Cheng Q, et al. Wax deposition rate model for heat and mass coupling of piped waxy crude oil based on non-equilibrium thermodynamics. Journal of Dispersion Science and Technology, 2018, 39(2): 259–269.CrossRefGoogle Scholar
Cheng Q, Pan C, Zhao Y, et al. Phenomenological study on heat and mass coupling mechanism of waxy crude oil pipeline transport process. Journal of Dispersion Science and Technology, 2017, 38(9): 1276–1284.CrossRefGoogle Scholar
Guo C, Nian X, Liu Y, et al. Analysis of 2D flow and heat transfer modeling in fracture of porous media. Journal of Thermal Science, 2017, 26(4): 331–338.ADSCrossRefGoogle Scholar
Huang Q, Wang J, Zhang J. Physical properties of wax deposits on the walls of crude pipelines. Petroleum Science, 2009, 6(1): 64–68.CrossRefGoogle Scholar
Teng H, Zhang J. Modeling the viscoelasto-plastic behavior of waxy crude. Petroleum Science, 2013, 10(3): 395–401.CrossRefGoogle Scholar
Hou L, Zhang J. Effects of thermal and shear history on the viscoelasticity of daqing crude oil. Petroleum Science and Technology, 2007, 25(5): 601–614.CrossRefGoogle Scholar
Zima P, Maršík F, Sedlář M. Cavitation rates in water with dissolved gas and other impurities. Journal of Thermal Science, 2003, 12(2): 151–156.ADSCrossRefGoogle Scholar
Wang ZH, Li JX, Zhang HQ, et al. Treatment on oil/water gel deposition behavior in non-heating gathering and transporting process with polymer flooding wells. Environmental Earth Sciences, 2017, 76(8): 326.CrossRefGoogle Scholar