磁性纳米破乳剂的设计合成及交变磁场促进破乳过程的机理研究

With the development of tertiary oil recovery, the oil extraction has turned into a different stage, in which the content of water in produced water is gradually increasing. And the content of polymer and surfactant goes up. The produced water with high oil content forms a complex and stable O/W emulsion system. Thus, it is more difficult to dispose of the produced water, which directly affects the process of the crude oil gathering and transferring and the normal production in oil field. Recently, magnetic nano-materials have strong adsorption property because of large specific surface and can be separeated from complex system because of magnetic response. So this nano-materials have a good prospect in wastewater treatment. In this project, magnetic demulsifier, which have many advantages such as recyclable, environmental friendly, high oil removal rate, easy seperation and so on due to its unique physical properties, are to be synthesized. This demulsifier aims at the phenomenon in which oil is wrapped by polymer. And studies on the mechanismof demulsification promoted by alternating magnetic field and mathematical model are to be set up, which can provide support for tertiary oil recovery and ensure the normal operation and general application of tertiary oil recovery and have far-reaching and realistic significance on the petroleum extraction.

随着“三次采油”技术的推广应用，我国原油开采逐步过渡到高含水期，采出液含水率越来越高，聚合物及活性剂等含量上升，O/W型油水乳状液稳定，乳化倾向严重，含油污水难以处理，直接影响到原油的集输处理和油田的正常生产。近些年来，磁性纳米材料因其比表面大具有较强的吸附性，对外加磁场有磁响应效应，通过磁分离能够从复杂相系统中分离出来，所以在污水处理中有着良好的前景。本研究针对 O/W型乳状液中油珠外层被聚合物包裹的特点，合成出新型的磁性纳米破乳剂，利用磁性材料特殊的物理性质，使磁性纳米破乳剂具有可回收利用、对环境友好、除油效率高、易分离等优点。通过交变磁场对磁性微球破乳剂的破乳增强机理进行研究，建立数学模型，为三次采油采出液的集输处理药剂的研制提供后备技术保障，保证三次采油技术的正常运行及全面展开，对石油深度开采具有现实意义和深远的发展意义。

利用溶剂热法制备出单分散的Fe3O4磁性微球，然后在其表面包裹一层SiO2，合成具有核壳结构的磁性微球，再应用硅烷偶联剂KH560对核壳微球进行基团功能化修饰，最后与现场用水分散性破乳剂5010进行接枝反应，制得磁性材料M-5010。 研究发现，Fe3O4磁性微球尺寸较为统一，颗粒均匀，粒径大约为420nm；而且磁性微球没有很明显的团聚现象产生，基本上呈单分散状态；包裹在微球表面的SiO2层的厚度约为38nm，核壳微球可以在水、乙醇中保存40h左右不发生沉降，其分散性能优良；M-5010有较高的磁化强度为35.1 emu·g-1，有回收利用的前景。使用正交试验对接枝反应条件进行探索优化，接枝率最佳的反应条件为：反应温度120℃，Fe3O4@SiO2-epoxy微球质量浓度0.20%，4-二甲氨基吡啶（DMAP）质量浓度0.08%，反相破乳剂5010的质量浓度0.80%，反应时间5h。研究模拟的O/W型含油污水中聚合物、表面活性剂、碱含量对破乳率的影响。实验结果显示：随着聚丙烯酰胺（HPAM）的质量浓度增大，破乳率有所增加，但是继续增加HPAM的质量浓度，破乳率会呈现下降趋势；随着表面活性剂的质量浓度的增大，破乳率呈现下降趋势；在最初阶段，破乳率随着碱的质量浓度增大而下降，随着碱的质量浓度的继续增大，乳状液的稳定性下降，破乳率有一定的增加。在破乳实验中，配制含油量为1000mg/L的O/W型模拟含油污水，其中表面活性剂的质量浓度分别为4mg/L、聚丙烯酰胺的质量浓度为100mg/L、碱的质量浓度为100mg/L。研究发现，当破乳剂的添加浓度为198mg/L、破乳时间为3h、破乳温度为60℃时，M-5010的破乳率达到95.3%；随着添加浓度、破乳时间及破乳温度的增大，破乳率均呈现增长的趋势；在整个实验过程中，M-5010的破乳效果要优于5010。通过磁铁将M-5010从破乳后的污水中分离后用于回收测试。研究发现，M-5010具有循环回收再利用的特征，随着循环次数的增加，破乳率逐渐下降，当循环次数增加到5次时，其破乳率下降到67.8%，仍然具有一定的除油效果。