The article examines the effect of the quantitative content of resins, asphaltenes and paraffin in oil on the pour point of oil. The effect of a depressant additive on the pour point of oil and the transition of its state from Newtonian to non-Newtonian is also shown. The process of paraffin crystals precipitation into the solution with a decrease in oil temperature and its transition from a Newtonian state to a non-Newtonian one is considered. It is noted that at a certain temperature, Newtonian oil turns into a colloidal solution and begins to acquire the properties of a non-Newtonian fluid. With a further decrease in temperature, the viscosity of the oil will increase, and the area of hysteresis loop between the shear rate and the magnitude of the shear stress increases. The effect of resins and asphaltenes on the process of oil cooling is considered. It is noted that neutral resins form true solutions with oil products, asphaltenes form suspensions and colloidal solutions. On the basis of a large number of previous experiments, it was found that the quantitative ratio of the mass of paraffin to the amount of resins and asphaltenes does not unambiguously determine the pour point of oil. It is shown that an increase in the pour point of oil with an increase in the paraffin content in it can be disturbed due to the qualitative ratio of resins, asphaltenes and paraffins, which leads to a depressant effect. The relationship between the pour point of oil and the critical transition temperature from Newtonian to non-Newtonian is also considered. The effectiveness of the depressant effect is manifested from the moment the oil transitions to the non-Newtonian state. It is assumed that under the influence of a depressant additive, the pour point and the critical temperature of the transition from Newtonian to non-Newtonian change by the same value. This assumption is based on experimental data obtained by various authors. The relevance of the results obtained is that technologically the temperature of the beginning of paraffin precipitation is more important than the pour point of oil. This is due to the fact that during the transition of oil to a non-Newtonian state, dynamic viscosity and static shear stress increase. Operation of the pipeline in the area of the non-Newtonian state of the liquid is impractical due to increasing losses and the threat of oil solidification when pumping is stopped.
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