The South China Sea Oil Characterization And Effects Of Pour Point And Viscosity Reducer On Its Rheological Properties

The development of the crude oil from South China Sea is of great significance to reduce the crude oil external dependence of our country. Chemical additives for pour point depression and viscosity reduction can improve the flowability of petroleum at low temperature, the research about effect of additives for pour point depression and viscosity reduction on rheological properties of crude oil has a significant scientific meaning and application prospect.Fristly, Nanhai crude oil was selected as the major research subject and its basic properties was measured. The resin and asphaltene were separated from the crude oil and their structural parameters and average molecular structural formula were confirmed through advanced instrumental analysis methods and comparable calculation methods. The main reason why Nanhai crude oil show high pour point and viscosity were determined, which is because the association of resin and asphaltene.Secondly, a long chain polymer was synthesized through the polymerization of maleic anhydride with vinyl acetate and octadecyl acrylate (combined crylic acid with octadecanl). Which get nitrogenous polymer pour point depressants and viscosity reducers EN through aminolysis reaction with nitrogen-containning compound. The solidifying point of Nanhai crude oil decresed 3℃ from 23℃ to 20℃ when EN is in 1000ppm addition. While the viscosity reduce from 375.0 Pa·s to 209.1 Pa·s at 15℃ and from 13.2 Pa·s to 9.1 Pa·s at 40℃,the viscosity-reducing rate is up to 44.2% and 31.1% repectively. The optimized polymerization conditions were determined through orthogonal test through the study of polymerization kinetics, the effect of temperature, concentration of monomer and initiator of the polymerization reaction rate is explored.Paper also draws the curve of rheological and viscosity-temperature and builds rheological and viscosity-temperature equation of the Nanhai crude oil system which added EN or not. By analyzing the shear rate and shear stress on the viscosity of system, the influence of thixotropy and yield stress by EN is determined, the impacting mechanism of rheological property is also be raised.Finally, the molecular simulation method is used to discussing the interaction of the asphalt aggregate and EN, building the system of Nanhai crude oil, calculating system energy, viscosity and shear stress parameters. This understanding reveal that EN destruct the associative structure of resin and asphaltene in the crude oil and reduce viscosity, and also provide an reference to the design of pour point depressants and viscosity reducers to destruct the associative structure of resin and asphaltene and the mechanism study of pour-viscosity reduction.