基于多重光散射原理的原油乳状液稳定性研究  

Study on Stability of Crude Oil Emulsion Based on Multiple Light Scattering Principle

作　　者：何宇廷 刘月田 柴汝宽 HE Yuting;LIU Yuetian;CHAI Rukuan(State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum (Beijing),Beijing 102249,China)

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249

出　　处：《西安石油大学学报（自然科学版）》2021年第6期30-36,43,共8页Journal of Xi’an Shiyou University（Natural Science Edition）

基　　金：国家科技重大专项(2017ZX05032004-002);国家重点基础研究发展计划(973计划)(2015CB250905);国家自然科学基金项目(51374222);中国石油重大科技专项(2017E-0405);中国石化重点科技项目(P18049-1)。

摘　　要：为探讨地层水中常见电解质类型对原油乳状液稳定性的影响,多角度分析了不同电解质(Mg^(2+)、Ca^(2+)、Na^(+))作用下乳状液的变化规律与机理。基于多重光散射实验研究乳状液的光谱变化特征和失稳规律,通过浓度和粒径实验分析乳状液失稳过程中液滴的迁移和生长变化特征,并以Zeta电位实验分析了乳状液液滴之间聚结的原因,最后结合DLVO理论探讨了乳状液失稳机理。研究发现:电解质促进乳状液由W/O/W型转相为O/W型乳状液而失稳。添加电解质后原油乳状液浓度下降加快,粒径增加,油滴之间絮凝和聚结作用增强。Mg^(2+)、Ca^(2+)、Na^(+)对乳状液的稳定性影响强度依次减弱,表现为对浓度、粒径和Zeta电位的作用效果依次降低。阳离子在原油液滴的表面吸附使液滴表面电荷密度和水化层厚度降低,液滴之间的范德华力增加,静电斥力减小,导致液滴相互碰撞和聚结的几率增加,乳状液失稳。To explore the influence of common electrolytes in formation water on the stability of crude oil emulsion,the varying law and mechanism of the emulsion under the effect of different electrolytes(Mg^(2+),Ca^(2+),Na^(+))were analyzed from multiple angles.The spectral variation characteristics and instability law of the crude oil emulsion were studied based on the multiple light scattering experiment.The migration and growth characteristics of droplets during the instability process of the emulsion were analyzed by concentration and particle size experiments.The coalescence causes of emulsion droplets were analyzed by Zeta potential experiment.In the end,the instability mechanism of the emulsion was discussed based on the DLVO theory.The research results show that the electrolyte promotes the transform of the emulsion from W/O/W to O/W type so as to lead its instability.After adding electrolyte,the concentration of crude oil emulsion decreases rapidly,the particle size increased,and the flocculation and coalescence of oil droplets were enhanced.The effect of Mg^(2+),Ca^(2+),Na^(+) on the stability of emulsion decreased in turn,which showed that their effect on concentration,particle size and Zeta potential decreased in turn.The adsorption of cations on the surface of the crude oil droplets reduced the surface charge density of the droplets and the thickness of the hydration layer.The van der Waals force between droplets increases and the electrostatic repulsion decreases,resulting in the increase of the probability of droplet collision and coalescence,and the emulsion lost stability finally.

关 键 词：乳状液 多重光散射原理 电解质 

分 类 号：TE357.46[石油与天然气工程—油气田开发工程]