含蜡原油粘弹性与蜡晶结构的关系研究
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摘要
原油中已结晶蜡的量、蜡晶形态和结构是决定原油流变性的主要因素,热力和剪切条件也正是通过影响原油中蜡晶的形态和结构对宏观流变性产生影响的。本文结合理论基础和实验研究,对人工蜡油和含蜡原油蜡晶微观特性进行了较为全面的研究,并对人工蜡油和原油低温条件下的宏观流变性与蜡晶的微观特性之间的关系作了进一步的研究。本文主要利用差示扫描量热仪测量了不同含蜡原油原油降温过程中析蜡量与温度的关系,考察胶凝过程中含蜡原油的结晶放热特性,根据实验数据确定了不同温度下含蜡原油的析蜡量,并结合流变仪在小振幅振荡剪切的模式下,研究胶凝过程中含蜡原油储能模量、损耗模量、损耗角等流变参数的变化规律。通过流变学测量,结合差示扫描量热仪考察的胶凝过程中含蜡原油的结晶放热特性,探寻粘弹性参数与已析出的蜡晶质量分数的关系,建立微观结构分形维数与析蜡量、粘弹性参数的关系模型,间接获得含蜡原油微观结构的分形维数,从而建立了含蜡原油宏观流变性与蜡晶的微观特性之间的定量关系。此外,测量含蜡原油的屈服值,得出了原油屈服值与已析出的蜡晶质量分数满足指数关系。从而更深入地揭示含蜡原油的胶凝机理,希望能为含蜡原油加热管道输送工艺的安全、经济运行以及停输再启动提供理论依据。
We all know that the content, the shape and the structure of the precipitated wax crystals are the major factors which are very important to crude oil rheology. The macroscopic rheological of crude oil is just affected by heat and shear conditions through affecting the shape and the structure of wax crystals. Therefore, Artificial waxy oil and crude oil’s microscopic characteristics are studied comprehensively in this paper combining with theoretical basis and experimental study. The relation between macroscopic rheological of crude oil and microscopic characteristics of wax crystals in the low temperature condition is also further studied in this paper. In this paper, the relation between wax content and temperature during cooling process of different waxy crude oil were mesured by Differential Scanning Calorimeter, the exothermic and crystallization characteristics of waxy crude oil during gelation process was investigated, and get the wax precipitation of waxy crude oil at different temperatures according to experimental data. Combined with the small amplitude oscillatory shear mode of rheometer, studied the storage modulus, loss modulus, loss angle changes during the gelation process of waxy crude oil. Through the rheological measurements, combined with the exothermic and crystallization characteristics of waxy crude oil during the gelation process, explore the relation between viscoelastic parameters and precipitated wax crystals. Established the relationship between micro-structure fractal dimension, the amount of wax precipitation and the the viscoelastic parameters, indirectly get the micro-structure fractal dimension of waxy crude oil, then established the relationship between macro-rheological properties of waxy crude oil and microscopic characteristics of wax crystals. In addition, measured the yield stress of waxy crude oil, indicated the exponential relationship between yield stress and precipitated wax crystals mass fraction. To deeply reveal the gelation mechanism of waxy crude oil, hoping to provide theoretical basis of safety, economic operation and the shutdown and restart for the heating pipeline transportation.
We all know that the content, the shape and the structure of the precipitated wax crystals are the major factors which are very important to crude oil rheology. The macroscopic rheological of crude oil is just affected by heat and shear conditions through affecting the shape and the structure of wax crystals. Therefore, Artificial waxy oil and crude oil’s microscopic characteristics are studied comprehensively in this paper combining with theoretical basis and experimental study. The relation between macroscopic rheological of crude oil and microscopic characteristics of wax crystals in the low temperature condition is also further studied in this paper. In this paper, the relation between wax content and temperature during cooling process of different waxy crude oil were mesured by Differential Scanning Calorimeter, the exothermic and crystallization characteristics of waxy crude oil during gelation process was investigated, and get the wax precipitation of waxy crude oil at different temperatures according to experimental data. Combined with the small amplitude oscillatory shear mode of rheometer, studied the storage modulus, loss modulus, loss angle changes during the gelation process of waxy crude oil. Through the rheological measurements, combined with the exothermic and crystallization characteristics of waxy crude oil during the gelation process, explore the relation between viscoelastic parameters and precipitated wax crystals. Established the relationship between micro-structure fractal dimension, the amount of wax precipitation and the the viscoelastic parameters, indirectly get the micro-structure fractal dimension of waxy crude oil, then established the relationship between macro-rheological properties of waxy crude oil and microscopic characteristics of wax crystals. In addition, measured the yield stress of waxy crude oil, indicated the exponential relationship between yield stress and precipitated wax crystals mass fraction. To deeply reveal the gelation mechanism of waxy crude oil, hoping to provide theoretical basis of safety, economic operation and the shutdown and restart for the heating pipeline transportation.
引文
[1] J M Letoffe, P Claudy, M. V. Kok, et al. Crude Oils: Characterization of Waxes Precipitated on Cooling by D.S.C. and Thermomicroscopy [J]. Fuel, 1995, 74(6): 810-817
[2] Holder G A,Winkler J. Wax Crystallization From Distillate Fuels [J]. J. Ins. Petrol, 1965(5): 228-252
[3] Tor Anderson, H. Scott Peters, Rosario A. Torres, et al. Wax Crystal Size Distribution Versus Composition [J]. Fuel, 2001, 80(11):1635-1638
[4] Moussa Kané, Madeleine Djabourov, Jean-Luc Volle, et al. Morphology of paraffin crystals in waxy crude oils cooled in quiescent conditions and under flow[J]. Fuel, 2003, 82(2), 127-135
[5] S P Srivastava, R S Tandon, P S Verma, et al: Crystallization Behaviour of N-paraffins in Bombay-High Middle-distillate wax/gel[J]. Fuel, 1992, 71(5), 533-537
[6] Cazaux G,Barre L, Brucy F, et al. Waxy Crude Cold Start: Assessment Through Gel Structural Properties [C], 1998, SPE 49213
[7]敬加强,杨莉,罗平亚等.含蜡原油结构的存在性研究[J].西南石油学院学报,2001,23(6): 67~70
[8]敬加强,杨莉,秦文婷等.含蜡原油结构形成机理研究[J].西南石油学院学报,2003,25(5): 49~52
[9]刘刚,黄一勇.含蜡原油中的蜡晶形态[J].油气储运,2004,23(1): 23~25
[10]朱金兆,朱清科等.分形维数计算方法研究进展[J].北京林业大学学报,2002,24(2): 26～33
[11] Dukhin, A.S.; Fluck, D.; Goetz, P.J.; et al. Characterization of Fractal Particles Using Acoustics, Electroacoustics, Light Scattering, Image Analysis, and Conductivity [J]. Langmuir, 2007, 23: 5338-5351
[12] Sinkóa, K.; Tormab, V.; Kovács. A. SAXS investigation of porous nanostructures [J]. Journal of Non-crystalline Solids, 2008, 354(52-54): 5466-5474
[13] Dongming Tang, Alejandro G. Marangoni. Fractal Dimensions of Simulated and Real Fat Crystal Networks in 3D Space [J]. J Am Oil Chem Soc, 2008, 85: 495-499
[14] Dàvila, E.; Parés, D. Structure of heat-induced plasma protein gels studied by fractal and lacunarity analysis [J]. Food Hydrocolloids, 2007, 21(2): 147-153
[15] Suresh S. Narine, Alejandro G. Marangoni. Fractal nature of fat crystal networks. The American Physical Society. 1999,59(2),1908-1920
[16]彭瑞东,谢和平,鞠杨.二维数字图像分形维数的计算方法[J]. 2004,33(1): 19~24
[17] P.Domínguez-García, Sonia Melle, M.A. Rubioc. Morphology of anisotropic chains in a magneto-rheological fluid during aggregation and disaggregation processes [J]. Journal of Colloid Interface Science, 2009, 333(1): 221-229
[18] Jun Zhang, Haijun Su, Bo Tang, et al. Fractal characteristic of laser zone remelted Al2O3/YAG eutectic in situ composite [J]. Journal of Crystal Growth, 2008, 310(2): 490-494
[19] Weon Gyu Shin, Jing Wang, Michael Mertler, et al. Structural properties of silver nanoparticle agglomerates based on transmission electron microscopy: relationship to particle mobility analysis [J]. Journal of Nanoparticle Research, 2009, 11(1): 163-173
[20] Dongming Tang, Alejandro G. Marangoni. Quantitative study on the microstructure of colloidal fat crystal networks and fractal dimensions [J]. Advances in Colloid and Interface Science, 2006,V(128-130): 257-265
[21] Wei-Heng Shih, Wan Y. Shih, Seong-II Kim, et a1. Scaling behavior of the elastic properties of colloidal gels[J].Phys.Rev.A, 1990, 42(8): 4772-4779
[22] Hua Wu, Massimo Morbidelli. A model relating structural of coloidal gels to their elastic properties [J]. Langmuir, 2001, 17(4):1030-1036
[23]刘贺,朱丹实,徐学明等.低酯桔皮果胶凝胶的动力学分析及分形研究[J].食品科学,2008,29(2): 76~81
[24]双凯,梁华庆,张劲军.含蜡原油蜡晶形态和结构的定量表征[J].石油大学学报,2002,26(5): 100~103
[25] Peng Gao, Jinjun Zhang, Guixia Ma. Direct image-based fractal characterization of morphologies and structures of wax crystals in waxy crude oils [J].Journal of Physics: Condensed Matte, 2006, 18(50): 11487~11506
[26]敬加强,路平,杨莉等.大庆原油加剂前后的蜡晶分形特性研究[J].西南石油大学学报,2008,30(2): 420~425
[27] Moussa Kané, Madeleine Djabourov, Jean-Luc Volle. Rheology and structure of waxy crude oils in quiescent and under shearing conditions [J]. Fuel, 2004, 83(11-12): 1591-1605
[28]侯磊,张劲军.含蜡原油低温粘弹性研究的现状与分析[J].石油大学学报,2004,28(6): 140~144
[29]李传宪.原油流变学[M].东营:中国石油大学出版社,2006
[30]李传宪,史秀敏.原油屈服值的测量特性[J].油气储运,2001,20(4): 44-46
[31]李传宪,李琦瑰.新疆胶凝原油屈服特性研究[J].油气储运,1999,18(12): 5~7
[32]侯磊,张劲军.含蜡原油屈服特性的试验研究[J].石油天然气学报,2007,29(6): 99~102
[33]侯磊,张劲军.含蜡原油屈服应力的研究进展及分析[J].油气储运,2005,24(3): 5～9
[34]彭建伟,韩善鹏,张劲军等.胶凝大庆原油不同加载时间下的屈服特性[J].中国石油大学学报,2008,32(4): 109~114
[35]彭建伟,张劲军,侯磊等.胶凝含蜡原油屈服时间研究[J].西南石油大学学报,2008,30(6): 145-148
[36]李传宪,李琦瑰.胶凝原油屈服值与结构特性参数之间的关系[J].油气储运,2000,19(11): 44～46
[37]高鹏.含蜡原油流变性与蜡晶形态、结构及原油组成间关系研究[D].北京:中国石油大学,2007
[2] Holder G A,Winkler J. Wax Crystallization From Distillate Fuels [J]. J. Ins. Petrol, 1965(5): 228-252
[3] Tor Anderson, H. Scott Peters, Rosario A. Torres, et al. Wax Crystal Size Distribution Versus Composition [J]. Fuel, 2001, 80(11):1635-1638
[4] Moussa Kané, Madeleine Djabourov, Jean-Luc Volle, et al. Morphology of paraffin crystals in waxy crude oils cooled in quiescent conditions and under flow[J]. Fuel, 2003, 82(2), 127-135
[5] S P Srivastava, R S Tandon, P S Verma, et al: Crystallization Behaviour of N-paraffins in Bombay-High Middle-distillate wax/gel[J]. Fuel, 1992, 71(5), 533-537
[6] Cazaux G,Barre L, Brucy F, et al. Waxy Crude Cold Start: Assessment Through Gel Structural Properties [C], 1998, SPE 49213
[7]敬加强,杨莉,罗平亚等.含蜡原油结构的存在性研究[J].西南石油学院学报,2001,23(6): 67~70
[8]敬加强,杨莉,秦文婷等.含蜡原油结构形成机理研究[J].西南石油学院学报,2003,25(5): 49~52
[9]刘刚,黄一勇.含蜡原油中的蜡晶形态[J].油气储运,2004,23(1): 23~25
[10]朱金兆,朱清科等.分形维数计算方法研究进展[J].北京林业大学学报,2002,24(2): 26～33
[11] Dukhin, A.S.; Fluck, D.; Goetz, P.J.; et al. Characterization of Fractal Particles Using Acoustics, Electroacoustics, Light Scattering, Image Analysis, and Conductivity [J]. Langmuir, 2007, 23: 5338-5351
[12] Sinkóa, K.; Tormab, V.; Kovács. A. SAXS investigation of porous nanostructures [J]. Journal of Non-crystalline Solids, 2008, 354(52-54): 5466-5474
[13] Dongming Tang, Alejandro G. Marangoni. Fractal Dimensions of Simulated and Real Fat Crystal Networks in 3D Space [J]. J Am Oil Chem Soc, 2008, 85: 495-499
[14] Dàvila, E.; Parés, D. Structure of heat-induced plasma protein gels studied by fractal and lacunarity analysis [J]. Food Hydrocolloids, 2007, 21(2): 147-153
[15] Suresh S. Narine, Alejandro G. Marangoni. Fractal nature of fat crystal networks. The American Physical Society. 1999,59(2),1908-1920
[16]彭瑞东,谢和平,鞠杨.二维数字图像分形维数的计算方法[J]. 2004,33(1): 19~24
[17] P.Domínguez-García, Sonia Melle, M.A. Rubioc. Morphology of anisotropic chains in a magneto-rheological fluid during aggregation and disaggregation processes [J]. Journal of Colloid Interface Science, 2009, 333(1): 221-229
[18] Jun Zhang, Haijun Su, Bo Tang, et al. Fractal characteristic of laser zone remelted Al2O3/YAG eutectic in situ composite [J]. Journal of Crystal Growth, 2008, 310(2): 490-494
[19] Weon Gyu Shin, Jing Wang, Michael Mertler, et al. Structural properties of silver nanoparticle agglomerates based on transmission electron microscopy: relationship to particle mobility analysis [J]. Journal of Nanoparticle Research, 2009, 11(1): 163-173
[20] Dongming Tang, Alejandro G. Marangoni. Quantitative study on the microstructure of colloidal fat crystal networks and fractal dimensions [J]. Advances in Colloid and Interface Science, 2006,V(128-130): 257-265
[21] Wei-Heng Shih, Wan Y. Shih, Seong-II Kim, et a1. Scaling behavior of the elastic properties of colloidal gels[J].Phys.Rev.A, 1990, 42(8): 4772-4779
[22] Hua Wu, Massimo Morbidelli. A model relating structural of coloidal gels to their elastic properties [J]. Langmuir, 2001, 17(4):1030-1036
[23]刘贺,朱丹实,徐学明等.低酯桔皮果胶凝胶的动力学分析及分形研究[J].食品科学,2008,29(2): 76~81
[24]双凯,梁华庆,张劲军.含蜡原油蜡晶形态和结构的定量表征[J].石油大学学报,2002,26(5): 100~103
[25] Peng Gao, Jinjun Zhang, Guixia Ma. Direct image-based fractal characterization of morphologies and structures of wax crystals in waxy crude oils [J].Journal of Physics: Condensed Matte, 2006, 18(50): 11487~11506
[26]敬加强,路平,杨莉等.大庆原油加剂前后的蜡晶分形特性研究[J].西南石油大学学报,2008,30(2): 420~425
[27] Moussa Kané, Madeleine Djabourov, Jean-Luc Volle. Rheology and structure of waxy crude oils in quiescent and under shearing conditions [J]. Fuel, 2004, 83(11-12): 1591-1605
[28]侯磊,张劲军.含蜡原油低温粘弹性研究的现状与分析[J].石油大学学报,2004,28(6): 140~144
[29]李传宪.原油流变学[M].东营:中国石油大学出版社,2006
[30]李传宪,史秀敏.原油屈服值的测量特性[J].油气储运,2001,20(4): 44-46
[31]李传宪,李琦瑰.新疆胶凝原油屈服特性研究[J].油气储运,1999,18(12): 5~7
[32]侯磊,张劲军.含蜡原油屈服特性的试验研究[J].石油天然气学报,2007,29(6): 99~102
[33]侯磊,张劲军.含蜡原油屈服应力的研究进展及分析[J].油气储运,2005,24(3): 5～9
[34]彭建伟,韩善鹏,张劲军等.胶凝大庆原油不同加载时间下的屈服特性[J].中国石油大学学报,2008,32(4): 109~114
[35]彭建伟,张劲军,侯磊等.胶凝含蜡原油屈服时间研究[J].西南石油大学学报,2008,30(6): 145-148
[36]李传宪,李琦瑰.胶凝原油屈服值与结构特性参数之间的关系[J].油气储运,2000,19(11): 44～46
[37]高鹏.含蜡原油流变性与蜡晶形态、结构及原油组成间关系研究[D].北京:中国石油大学,2007