重质油包水乳液破乳过程及降黏强化机制

doi:10.16085/j.issn.1000-6613.2021-1708

摘要/Abstract

摘要：

重质油包水（W/O）乳液普遍存在于石油开采与加工过程中，因其高黏度、高密度、强界面稳定特性，导致重质油包水乳液分离困难，生产成本增加。为了提高重质W/O乳液的分离效率，本文探究了温度与甲苯加入量对重质油黏度的影响规律。在此基础上，研究了上述降黏过程与脱水率之间的协同机制。采用自制的TJU-3破乳剂对重质W/O乳液进行破乳，通过调整破乳剂在乳液中的浓度和破乳温度得到了最佳工艺条件。利用分子模拟的方法构建了重质油平均分子模型并计算了SARA四组分在不同甲苯含量的重质油中的扩散系数，分析了甲苯添加量对重质油中SARA四组分相互作用的影响规律，研究了沥青质分子和TJU-3破乳剂分子在油水界面的运移过程。结果表明：重质油的黏度降低到1500mPa·s时，可实现在1h内完全破乳；黏度降低到50mPa·s时可实现在20min内完全破乳。当破乳剂在乳液中的浓度为400mg/L时，乳液的脱水率最高；破乳温度为60℃时，破乳速度最快。SARA四组分中胶质的扩散系数增大最显著，是重质油的黏度能被甲苯迅速降低的主要原因。TJU-3分子能够破坏沥青质界面膜，进而实现破乳。该协同机制和工艺条件可为石油工业中重质W/O乳液的低温快速破乳工艺提供参考。

关键词: 重质油包水乳液, 破乳, 甲苯, 降黏, 分子模拟, 沥青质

Abstract:

Water-in-heavy oil（heavy W/O）emulsions widely exist in the petroleum exploration and petrochemical processing. Due to their high viscosity, high density, and strong interface stability, the separation of heavy W/O emulsions is fairly difficult, inevitably leading to an increasing cost in production. To enhance the separation efficiency of heavy W/O emulsions, in this study, the influence of temperature and toluene addition on the viscosity of heavy oil was systematically investigated. On this basis, the synergistic mechanism between viscosity reduction and dehydration ratio was discussed. A proposed TJU-3 demulsifier was used to break the heavy W/O emulsions. The optimal process conditions were obtained by varying the demulsifier concentration and the demulsification temperature. The molecular simulation method was used to build the heavy oil average molecular model and calculate the diffusion coefficient of SARA in the heavy oil with different content of toluene. The effect of toluene on the interaction of SARA in heavy oil was analyzed and the transport process of asphaltenes and TJU-3 demulsifier molecules at oil-water interface was studied. The results showed that a complete demulsification could be achieved within 1h when the viscosity of the heavy oil was reduced to 1500mPa·s. When the viscosity was reduced to 50mPa·s, the demulsification could be completed within 20min. When the concentration of demulsifier in the emulsions was 400mg/L, the dehydration ratio of the emulsions was the highest. When demulsification temperature was 60℃, demulsification rate was the highest. The diffusion coefficient of resins increased most significantly in SARA components, which was the main reason that the viscosity of heavy oil could be rapidly reduced by toluene. The TJU-3 demulsifier could break the asphaltene interface film, which achieved the demulsification of heavy W/O emulsions. The synergistic mechanism and technological conditions can provide reference for rapid demulsification of heavy W/O emulsion at low temperature in petroleum industry.

Key words: water-in-heavy oil emulsions, demulsification, toluene, viscosity reduction, molecular simulation, asphaltenes

中图分类号:

TE622

张辛铖, 何林, 隋红, 李鑫钢. 重质油包水乳液破乳过程及降黏强化机制[J]. 化工进展, 2022, 41(7): 3534-3544.

ZHANG Xincheng, HE Lin, SUI Hong, LI Xingang. Demulsification process and enhancement by viscosity reduction for water-in-heavy oil emulsions[J]. Chemical Industry and Engineering Progress, 2022, 41(7): 3534-3544.

图/表 16

参考文献 30

1	SANTOS R G, LOH W, BANNWART A C, et al. An overview of heavy oil properties and its recovery and transportation methods[J]. Brazilian Journal of Chemical Engineering, 2014, 31(3): 571-590.
2	HE L, LIN F, LI X G, et al. Interfacial sciences in unconventional petroleum production: from fundamentals to applications[J]. Chemical Society Reviews, 2015, 44(15): 5446-5494.
3	王君妍, 白云, 马国强, 等. 重质油-固体系分离与资源化回收研究进展[J]. 化工进展, 2019, 38(1): 649-663.
	WANG Junyan, BAI Yun, MA Guoqiang, et al. Recent advances in separation and recovery of oil from heavy oil-solid systems[J]. Chemical Industry and Engineering Progress, 2019, 38(1): 649-663.
4	NIU Z, MA X M, MANICA R, et al. Molecular destabilization mechanism of asphaltene model compound C5Pe interfacial film by EO-PO copolymer: experiments and MD simulation[J]. The Journal of Physical Chemistry C, 2019, 123(16): 10501-10508.
5	ZHANG L Y, XU Z H, MASLIYAH J H. Langmuir and Langmuir-Blodgett films of mixed asphaltene and a demulsifier[J]. Langmuir, 2003, 19(23): 9730-9741.
6	KIRAN S K, NG S, ACOSTA E J. Impact of asphaltenes and naphthenic amphiphiles on the phase behavior of Solvent-Bitumen-Water systems[J]. Energy & Fuels, 2011, 25(5): 2223-2231.
7	GOUAL L, SEDGHI M, ZENG H, et al. On the formation and properties of asphaltene nanoaggregates and clusters by DC-conductivity and centrifugation[J]. Fuel, 2011, 90(7): 2480-2490.
8	HOEPFNER M P, VILAS BÔAS FÁVERO C, HAJI-AKBARI N, et al. The fractal aggregation of asphaltenes[J]. Langmuir, 2013, 29(28): 8799-8808.
9	SPIECKER P M, GAWRYS K L, TRAIL C B, et al. Effects of petroleum resins on asphaltene aggregation and water-in-oil emulsion formation[J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2003, 220(1/2/3): 9-27.
10	KUAN Y H, WU F H, CHEN G B, et al. Study of the combustion characteristics of sewage sludge pyrolysis oil, heavy fuel oil, and their blends[J]. Energy, 2020, 201: 117559.
11	YANG F, TCHOUKOV P, PENSINI E, et al. Asphaltene subfractions responsible for stabilizing water-in-crude oil emulsions. Part 1: Interfacial behaviors[J]. Energy & Fuels, 2014, 28(11): 6897-6904.
12	YANG F, TCHOUKOV P, DETTMAN H, et al. Asphaltene subfractions responsible for stabilizing water-in-crude oil emulsions. Part 2: Molecular representations and molecular dynamics simulations[J]. Energy & Fuels, 2015, 29(8): 4783-4794.
13	QIAO P Q, HARBOTTLE D, TCHOUKOV P, et al. Asphaltene subfractions responsible for stabilizing water-in-crude oil emulsions. Part 3. Effect of solvent aromaticity[J]. Energy & Fuels, 2017, 31(9): 9179-9187.
14	HOU J, FENG X H, MASLIYAH J, et al. Understanding interfacial behavior of ethylcellulose at the water-diluted bitumen interface[J]. Energy & Fuels, 2012, 26(3): 1740-1745.
15	FAN Y R, SIMON S, SJÖBLOM J. Interfacial shear rheology of asphaltenes at oil-water interface and its relation to emulsion stability: influence of concentration, solvent aromaticity and nonionic surfactant[J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2010, 366(1/2/3): 120-128.
16	FAN Y R, SIMON S, SJÖBLOM J. Chemical destabilization of crude oil emulsions: effect of nonionic surfactants as emulsion inhibitors[J]. Energy & Fuels, 2009, 23(9): 4575-4583.
17	MA J, LI X G, ZHANG X Y, et al. A novel oxygen-containing demulsifier for efficient breaking of water-in-oil emulsions[J]. Chemical Engineering Journal, 2020, 385: 123826.
18	MA J, YANG Y L, LI X G, et al. Mechanisms on the stability and instability of water-in-oil emulsion stabilized by interfacially active asphaltenes: role of hydrogen bonding reconstructing[J]. Fuel, 2021, 297(8): 120763.
19	ASTM International. Standard test method for determination of asphaltenes (heptane insolubles) in crude petroleum and petroleum products: [S]. 2017.
20	中华人民共和国国家质量监督检验检疫总局, 中国家标准化管理委员会. 原油水含量的测定蒸馏法: [S]. 北京: 中国标准出版社, 2006.
	General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China, Standardization Administration of the People’s Republic of China. Crude petroleum determination of water—Distillation method: [S]. Beijing: Standards Press of China, 2006.
21	ALVES R S, MAIA D L H, FERNANDES F A N, et al. Synthesis and application of castor oil maleate and castor oil maleate-styrene copolymers as demulsifier for water-in-oil emulsions[J]. Fuel, 2020, 269: 117429.
22	NIKKHAH M, TOHIDIAN T, RAHIMPOUR M R, et al. Efficient demulsification of water-in-oil emulsion by a novel nano-titania modified chemical demulsifier[J]. Chemical Engineering Research and Design, 2015, 94: 164-172.
23	LI X G, WANG J Y, HE L, et al. Ionic liquid-assisted solvent extraction for unconventional oil recovery: computational simulation and experimental tests[J]. Energy & Fuels, 2016, 30(9): 7074-7081.
24	FRAGA A K DA, OLIVEIRA P F, OLIVEIRA L F S, et al. Evaluation of nanoemulsions based on silicone polyethers for demulsification of asphaltene model emulsions[J]. Journal of Applied Polymer Science, 2016, 133(44): 44174-44182.
25	ZHANG L F, HE G J, YE D F, et al. Methacrylated hyperbranched polyglycerol as a high-efficiency demulsifier for oil-in-water emulsions[J]. Energy & Fuels, 2016, 30(11): 9939-9946.
26	LI X G, MA J, BIAN R Z, et al. Novel polyether for efficient demulsification of interfacially active asphaltene-stabilized water-in-oil emulsions[J]. Energy & Fuels, 2020, 34(3): 3591-3600.
27	成琛, 王飞, 刘英杰, 等. 一种石蜡基原油低温破乳剂的合成研究[J]. 现代化工, 2017, 37(4): 67-70.
	CHENG Chen, WANG Fei, LIU Yingjie, et al. Synthesis of a paraffin-based low-temperature crude oil demulsifier[J]. Modern Chemical Industry, 2017, 37(4): 67-70.
28	KÄRGER J. Straightforward derivation of the long-time limit of the mean-square displacement in one-dimensional diffusion[J]. Physical Review A, 1992, 45(6): 4173-4174.
29	NORDGÅRD E L, SØRLAND G, SJÖBLOM J. Behavior of asphaltene model compounds at W/O interfaces[J]. Langmuir, 2010, 26(4): 2352-2360.
30	ROUX B. The calculation of the potential of mean force using computer simulations[J]. Computer Physics Communications, 1995, 91(1/2/3): 275-282.

组分名称	M_n	M_w	M_w/M_n	元素分析（质量分数）%
组分名称	M_n	M_w	M_w/M_n	C	H	O	N	S
重质油	494	1936	3.92	85.28	10.05	3.57	0.68	0.42
饱和分	390	539	1.38	85.09	11.60	3.23	0.08	0
芳香分	338	850	2.51	86.36	9.37	3.40	0.33	0.53
胶质	546	2899	5.31	85.44	8.57	4.08	1.42	0.49
沥青质	2385	14097	5.91	78.14	7.35	3.84	0.95	9.72

组分名称	M_n	M_w	M_w/M_n	元素分析（质量分数）%
组分名称	M_n	M_w	M_w/M_n	C	H	O	N	S
重质油	494	1936	3.92	85.28	10.05	3.57	0.68	0.42
饱和分	390	539	1.38	85.09	11.60	3.23	0.08	0
芳香分	338	850	2.51	86.36	9.37	3.40	0.33	0.53
胶质	546	2899	5.31	85.44	8.57	4.08	1.42	0.49
沥青质	2385	14097	5.91	78.14	7.35	3.84	0.95	9.72

甲苯质量分数/%	扩散系数/10^-10m²·s^-1
甲苯质量分数/%	SARA	增长率/%	沥青质	增长率/%	胶质	增长率/%
0	0.210	—	0.135	—	0.098	—
4	0.266	26.7	0.155	14.8	0.141	43.9
8	0.300	42.9	0.180	33.3	0.160	63.3
12	0.333	58.6	0.237	75.6	0.233	137.8
16	0.387	84.3	0.352	160.7	0.263	168.4
20	0.488	132.4	0.435	222.2	0.332	238.8

甲苯质量分数/%	扩散系数/10^-10m²·s^-1
甲苯质量分数/%	SARA	增长率/%	沥青质	增长率/%	胶质	增长率/%
0	0.210	—	0.135	—	0.098	—
4	0.266	26.7	0.155	14.8	0.141	43.9
8	0.300	42.9	0.180	33.3	0.160	63.3
12	0.333	58.6	0.237	75.6	0.233	137.8
16	0.387	84.3	0.352	160.7	0.263	168.4
20	0.488	132.4	0.435	222.2	0.332	238.8

甲苯质量分数/%	沥青质-胶质/kJ·mol^-1	沥青质-芳香分/kJ·mol^-1	胶质-芳香分/kJ·mol^-1	体系总能量/kJ·mol^-1
0	10.41	6.47	11.01	5.26×10⁴
4	7.17	6.40	10.75	4.77×10⁴
8	6.62	6.12	10.61	4.61×10⁴
12	6.29	5.92	10.42	4.52×10⁴
16	6.05	5.83	10.38	4.49×10⁴
20	5.92	5.74	10.35	4.39×10⁴