原油正构烷烃沥青质聚沉机理研究及沉淀量测定

用IP 143标准方法测定了我国孤岛和草桥原油正构烷沥青质沉淀量。结果表明两种原油的沥青质沉淀量均随沉淀剂分子量增大而减小、随剂油比增大而增大。在原油沥青质 胶质胶束模型的基础上提出了一种新的沥青质聚沉机理 ,该机理的基本假设是原油中沥青质分子以胶束形式存在 ,其中胶核为沥青质缔合物 ,溶剂化层为胶质和溶剂分子。通过分析沉淀剂性质、剂油比、体系温度和压力等对沥青质 胶质胶束稳定性的影响得出了沥青质沉淀点、沉淀量、沉淀物平均分子量以及沉淀物平均颗粒大小随沉淀剂性质和剂油比等因素变化的规律。经比较说明 ,这些规律与本文及文献实验结果相符

N-alkane asphaltene precipitation and the mechanism of their formation

The stand ard IP 143 method has been used to determine the amount of asphaltene precipita tion when the Gudao and Caoqiao crude oils were diluted with various n alkanes. The results show that the amount of asphaltene precipitation decreases with the molecular weight of n alkane and increases with the precipitant to oil ratio . A new mechanism of asphaltene precipitation has been proposed by using the the rmodynamic micellization model. The new mechanism is based on the assumption tha t most asphaltene molecules exist as micelles in a crude, where the micellar cor e is the asphaltene associates and the solvated shell consists of resins and the solvent. The influences of the nature of the alkane, the alkane to oil ratio, temperature and pressure on the stability of the asphaltene resin micelles hav e been analyzed. The trends concerning their effects on the onset of asphaltene precipitation, the amount of asphaltenes precipitated, the mean molecular weight , and the mean particle size have been presented and have been shown to be in go od agreement with our experimental results and those reported in the literatures .