不同极性的乙烯-醋酸乙烯酯共聚物对原油中沥青质分散稳定性的影响

Effect of Ethylene-Vinyl Acetate Copolymers With Different Polarities on Asphaltene Dispersion Stability in Crude Oil

以储罐储存的阿曼原油及不同醋酸乙烯酯基团(VA)含量的乙烯-醋酸乙烯酯共聚物(EVA)为研究对象,通过实验研究了添加EVA前后原油中沥青质的动态稳定性、离心稳定性及粒度分布的变化,进而探讨了在相同相对分子质量的情况下,VA基团含量对EVA分散稳定沥青质作用的影响。结果表明,VA基团质量分数为30%的EVA分散稳定沥青质的作用最强;EVA通过吸附于沥青质表面,抑制沥青质絮凝沉淀,从而起到分散稳定沥青质的作用;非极性基团的空间阻碍作用和EVA与沥青质间的吸附作用共同影响了EVA分散稳定沥青质的效果;增加VA含量会导致EVA中非极性链的数量和长度减小,减弱EVA非极性链的空间阻碍作用,从而减弱EVA分散稳定沥青质的效果。分子动力学模拟表明,增加VA含量会增强EVA与沥青质的吸附作用,从而提高EVA分散稳定沥青质的效果。

Effect of the polar group contents of polyethylene-vinyl acetate(EVA)on asphaltene dispersion stability is studied.With using the long-term stored Oman crude oil as experimental sample,dynamic stability,centrifugal stability and particle size distribution of asphaltenes in crude oil with/without EVA are experimentally investigated.Experimental results show that EVA can absorb on asphaltene surface to inhibit asphaltenes flocculation,and thus cause asphaltenes to be dispersed.Dispersion efficiency of EVA lies on the balance between steric hindrance effect by non-polar group and attractions of EVA and asphaltenes.Increasing VA content leads to less non-polar groups and short chain length in EVA,and thus reduces non-polar groups′steric hindrance of EVA.This causes less asphaltene dispersion efficiency of EVA.Meanwhile,molecular dynamic simulation suggests that increasing VA content leads to enhanced interactions between EVA and asphaltenes,which improves EVA dispersion efficiency.