剪切对几种加剂原油流动性影响与其组成关系

为揭示剪切（泵的强剪切和管道的弱剪切）对原油流动性的内在影响机理，给新管线建设及管线安全运行提供决策依据，采用气相色谱、核磁共振、DSC热分析和偏光显微镜等分析方法，对5种原油的组成、蜡结构、析蜡点和蜡晶形态进行分析；按照参考文献报道的模拟实验方法，评价泵强剪切和管道弱剪切对5种原油添加降凝剂后的原油流动性影响。结果发现，在析蜡温度点以上，原油中仅有极少量的蜡晶析出，泵强剪切和管道弱剪切对原油的流动性无影响。在析蜡高峰温度区内，原油中有大量的蜡晶析出，泵强剪切对原油流动性有恶化作用；管道弱剪切对原油流动性的影响与原油的组成（蜡含量、胶质沥青质含量）和蜡的结构（碳数分布、支链度）有关，既对某些原油的流动性有改善作用而对某些原油的流动性有恶化作用，导致上述现象的主要原因是析蜡高峰温度区内的剪切对蜡晶形态和蜡晶生长影响较大。

Relationship Between the Shear Effect of the Flowability and Composition of Typical Crude Oils

In order to reveal the intrinsic effect mechanism of shear (including strong pump shear and weak pipeline shear) on the flowability of the crude oil modified with pour point depressant, and to provide decision-making basis for new pipeline construction and pipeline safe operation, crude oil components, wax structure and wax crystal morphology of the five kinds of crude oil are analyzed by GC, ¹H-NMR, DSC and polarization microscope and effect of pump strong shear and pipeline weak shear on the flowability of the five kinds of crude oil modified with pour point depressant are evaluated by the simulation experimental method reported. It is found that only a very small amount of wax crystals precipitate from the crude oil above the wax appearance temperature, the shear has little effect on the wax crystal structure and does not influence the flowability of the crude oil modified with pour point depressant. In the range of the wax appearance peak temperature, there are a large number of wax crystals in crude oil, the strong pump shear can deteriorate the flowability of the crude oil modified with pour point depressant, and deterioration degree is related to the crude oil composition (wax content, resin content, asphaltene content) and wax structure (carbon number distribution of wax, branched-chain degree of wax); the weak pipeline shear can improve the flowability of some crude oil but also can deteriorate the flowability of other crude oil, which is related to crude oil composition and wax structure. The main reason for the above-mentioned phenomenon is that the shear has a great influence on the wax crystal structure and the wax crystal growth at the wax appearance temperature range.