表面活性剂对原油流变性的作用与分子动力学模拟

选取5种合成降凝剂中常用的表面活性剂：丙烯酸、丙烯酰胺、顺丁烯二酸酐、乙酸乙烯酯和苯乙烯，采用试验和分子动力学模拟相结合的方法，考察其对原油流变性的影响。结果表明：在加剂量为2000mg/kg的条件下，5种表面活性剂的加入对原油的凝点影响较小，均使原油的凝点仅提高1℃；对原油的黏度和屈服值影响较大，其影响程度从大到小的顺序为：丙烯酰胺>丙烯酸>苯乙烯>顺丁烯二酸酐>乙酸乙烯酯；与空白原油体系相比，5种加剂原油体系势能降低，非键能负向升高，作用效果强弱顺序与试验结果相吻合，从分子层面解释了表面活性剂对原油流变性产生影响的作用机理。

EFFECT OF SURFACTANT ON RHEOLOGICAL PROPERTIES OF CRUDE OIL AND MOLECULAR DYNAMICS SIMULATION

Five surfactants (acrylic acid, acrylamide, maleic anhydride, vinyl acetate and styrene) commonly used as synthetic pour point depressants were selected and the effects of these surfactants on the rheological properties of crude oil were investigated by means of experiments and molecular dynamics simulation.The results showed that at the dosage of 2000ug/g, the addition of 5 surfactants had little effect on the freezing point of crude oil, which increased the freezing point of crude oil by only 1℃; but the effect on the viscosity and yield value of crude oil was significant, the relative degree of influence as follows: acrylamide>acrylic acid>styrene>maleic anhydride>vinyl acetate; compared with the blank crude oil system, the potential energy of the crude oil systems with five additives decreased, and the non-bond energy increased negatively. The order of the effect was consistent with the experimental results. The mechanism of the effect of surfactant on the rheology of crude oil was explained from the molecular level.