Abstract: Using differential scanning calorimeter （DSC ）， the crystallization abilities of polyacrylate （PA） pour point depressant and waxy crude oils doped/undoped with PA were studied；then the morphology of wax crystals in the waxy crude
oils doped/undoped with PA was investigated through a polarized light microscope and the depressive effect of PA on Changqing and Qinghai waxy crude oils was evaluated by the pour point tests and rheological experiments．The results show that the crystallization ability of PA improved greatly by increasing the alkyl side chain length of PA but kept unchanged with the increase of average molecular weight of PA．The addition of PA can inhibit the wax precipitation and decrease the wax appearance temperature of waxy crude oils．The size of wax crystals become larger and the structure of them become compact after PA addition，leading to the great improvement of the low temperature rheology of waxy crude oils．The depressive effect of PA on waxy crude oils are related to the crude oil composition and the molecular structure of PA．With the increasing of wax content and the fraction of wax with large carbon number， the depressive effect greatly decreased． The average molecular
weight of PA affected its depressive effect by controlling the solubility of PA in waxy crude oils：the solubility of PA in crude oils decreased with increasing the average molecular weight of PA， thus reducing the interactions between waxes and PA molecules and inhibiting the depressive effect of PA．The better matching the alkyl side chain of PA with the carbon number ofwax in crude oils，the better depressive effect of PA．

Key words: Polyacrylate , Pour point depressant , Crystallization ability , Wax crystal morphology , Depressive effect

摘要： 采用 DSC热分析仪研究了聚丙烯酸酯(PA)降凝剂的结晶性能及加剂前后含蜡原油的结晶特性，通过偏光显微镜观察了加剂前后原油中蜡晶形貌，并通过凝点试验和流变实验评价了PA降凝剂对长庆、青海两种含蜡原油的降凝效果。结果表明，PA降凝剂的结晶性能随烷基侧链碳数的增长显著提高，但不受降凝剂平均相对分子质量的影响。添加PA降凝剂能够抑制原油中蜡晶的析出、降低原油析蜡点，并且使原油中蜡晶尺寸变大，结构变紧凑，从而能够释放更多的液态油分，改善含蜡原油的低温流变性。PA降凝剂对含蜡原油的降凝效果与原油组成和降凝剂结构有关，原油中蜡含量越高、高碳数石蜡所占比例越大，降凝剂的降凝效果越差；随着降凝剂平均相对分子质量的提高，PA分子在原油中的溶解性变差，卷曲程度提高，导致PA与石蜡间作用力减弱，降凝效果变差；PA 烷基侧链碳数与原油中石蜡碳数越匹配，降凝剂分子与石蜡的作用越强，降凝效果也越理想。

关键词: 聚丙烯酸酯 , 降凝剂 , 结晶性能 , 蜡晶形貌 , 降凝效果