石蜡含量与测温对W/O模型原油乳状液稳定性的影响

Effects of Paraffin Wax Content and Test Temperature on Stability of W/O Crude Oil Emulsion

通过原油物性测量、乳状液宏观稳定性测量与微观观察、油水界面特性分析等手段,研究了石蜡含量与测量温度对W/O模型原油乳状液稳定性的影响。结果表明,增大石蜡含量使得模型原油析蜡点升高但削弱了油相中沥青质稳定性;提高石蜡含量显著恶化模型原油流变性。测量温度显著影响乳状液稳定性:测量温度为30℃时(高于析蜡点),增大石蜡含量促进沥青质的界面吸附,降低油水界面张力并增强沥青质界面膜的强度,这有助于小水滴的形成且在一定程度上提高乳状液稳定性;测量温度为15℃时(低于析蜡点),增大石蜡含量促进了结构更强蜡晶网络的形成,该网络通过束缚水滴大幅提高乳状液稳定性。同时,石蜡含量最高(15%)的乳状液中水滴粒度最小且数量最多,可作为有效蜡晶成核剂促进水滴表面蜡晶颗粒膜的形成,该蜡晶颗粒膜也有助于提高乳状液稳定性。

The effects of paraffin wax content and test temperature on the stability of W/O crude oil emulsion were studied by the physical property test of the crude oils,the macroscopic stability measurement and microscopic observation of the emulsions and the interfacial properties analysis of oil and water.The results show that increasing the content of paraffin wax enhances the wax appearance temperature of the crude oils but weakens the stability of asphaltene in oil phase.The rheology of the crude oils deteriorates greatly with increasing the content of paraffin wax.When the test temperature is 30°C(higher than the wax precipitation point),the increase of paraffin content promotes the interfacial adsorption of asphaltene,reduces the interfacial tension of oil and water and enhances the strength of the asphaltene interfacial film,which contributes to the formation of small droplets and improves the stability of emulsion to a certain extent.When the test temperature is 15°C(lower than the wax precipitation point),increasing the paraffin content promotes the formation of stronger wax crystal network,which greatly improves the stability of the emulsion by irreducible water droplets.At the same time,the emulsion with the highest paraffin content(15%)has the smallest particle size and the largest number of water droplets.It can be used as an effective wax crystal nucleating agent to promote the formation of wax crystal particle film on the surface of water droplets.The wax crystal particle film also helps to improve the stability of emulsion.