Abstract: In order to enrich the methods for identifying whether high temperature oxidation occurs and the degree of high temperature oxidation during the fire flooding development, the real boiling point distillation method was applied to separate the crude oil before and after the effectiveness of fire flooding in Hongqian Area of Xinjiang Oilfield, the corresponding real boiling point distillation curves were plotted, and the acid value of each fraction was measured. The high-resolution mass spectrometry was used to analyze different types of acidic compounds under the condition of electrospray ionization source in negative ion mode, and the equivalent double bond index (DBE) and carbon number distribution of O2-type components were classified in details. The results show that although the fluctuation range of the acid value of crude oil before and after the effectiveness of fire flooding is less than 1.0 mg/g, the content of low and medium boiling point components in the effected crude oil and the yield of real boiling point distillation mass are significantly improved, some components of the effected crude oil are oxidized to generate compounds containing active hydrogen functional groups, and two peaks appeared in the boiling point range of 200-250 ℃and 300-420 ℃. The mass spectrometry analysis shows that the relative abundances of DBE 3 and 4 in the O2 components of the fire flooding effected crude oil increases, and the proportion of two-membered and three-membered naphthenic acids increases. The research results can provide guidance for the analysis of crude oil fire flooding process and the refining of distillate products.

Key words: fire flooding, crude oil component, hydrogen component change, real boiling point distillation, equivalent double bond index, O2 type