稠油二氧化碳降粘的化学机制研究

摘要

In order to understand the mechanism of heavy oil viscosity reduction in CO2 flooding, the solubility of carbon dioxide in heavy oil was determined under different pressure, and the effect on heavy oil chemical composition of CO2 processing was analyzed.Furthermore, the differences between the extracted oil processed by supercritical CO2 and the heavy oil were analyzed.The result shows that CO2 doesn't change the chemical composition of heavy oil, although its solubility is high in heavy oil, it can get to 105 kg/m3.During supercritical CO2 extraction, saturates have higher solubility in supercritical CO2 than resins and asphaltenes.Then the colloidal structure of heavy oil was destroyed during supercritical CO2 extraction.The viscosity reduction mainly came from the dilution effect of soluble CO2.But the supercritical CO2 replaced the small molecules in solvation layer of asphaltene colloids, and reduced the volume of dispersing phase, which also decreased the viscosity.%为认识二氧化碳降粘的化学机制,考察了不同压力下二氧化碳在胜利稠油中的溶解度、二氧化碳处理对稠油化学组成的影响以及超临界二氧化碳对稠油的萃取行为.结果表明,二氧化碳在稠油中有很高的溶解度,可达105 kg/m3,但不改变稠油的化学组成;超临界二氧化碳萃取过程中,对饱和分的溶解能力强于胶质和沥青质,会破坏稠油的胶体化学结构.二氧化碳降粘主要来自于稀释作用,但胶体体系改变后,会释放出溶剂化层中的小分子,减小分散相体积,降低体系粘度.