丙烯酸十八酯-苯乙烯共聚物对含蜡原油改性效果与分子动力学模拟

合成了单体配比不同的丙烯酸十八酯-苯乙烯共聚物(OAS)降凝剂,采用实验与分子动力学模拟相结合的方法对降凝剂的性能进行评价。实验结果表明,OAS降凝剂的降凝减黏性能随丙烯酸十八酯比例的增加呈现出先增大后减小的趋势。在2000 mg/kg加剂量下,苯乙烯与丙烯酸十八酯摩尔比为1∶3的降凝剂OAS-4能使含蜡原油凝点降低4℃,降凝效果最好,并能有效改善原油的黏度和屈服值。模拟结果表明,加入OAS降凝剂能有降低石蜡体系和沥青质-胶质体系的平均密度,提高体系的势能与非键能;OAS降凝剂的加入能有效阻止蜡晶形成三维网状结构,拆散沥青质和胶质的堆砌结构;加入OAS-4的体系平均密度最低、势能上升最多,效果最佳。分子动力学模拟结果与实验结果一致。

Modification effect and molecular dynamics simulation of octadecyl acrylate-styrene copolymer on waxy crude oil

Octadecyl acrylate-styrene(OAS)pour point depressants with different monomer ratios were synthesized,and the performance of the pour point depressants was evaluated through experiments and molecular dynamics simulation.The experimental results show that the pour point and viscosity reduction performance of OAS increases at first and then decreases as the content of stearyl acrylate increases.At a dosage of 2000 mg/kg,when the mole ratio of styrene to octadecyl acrylate is 1∶3,the pour point of the waxy crude oil can be reduced by 4℃,and the pour point depressing effect is the best,which can effectively improve the viscosity and yield value of crude oil.The simulation results show that the addition of OAS pour point depressant can reduce the average density of paraffin wax and asphaltene-gum and increase the potential energy and non-bond energy of the system.The addition of OAS pour point depressant can effectively prevent wax crystals from forming a three-dimensional network structure and dismantle the stacking structure of asphaltene-gum.Among them,OAS with mole ratio of styrene to octadecyl acrylate of 1∶3 has the lowest average density,the highest potential energy increase and the best improvement,which is consistent with the experimental results.