Experimental Study And Numerical Simulation Of Oxidative Heating Of Air Injection Crude Oil

As one of gas injection oil producing technologies, High-Pressure Air Injection (HPAI) is a new method to enhance oil recovery. In recent years, with the maturity and commercial application of HPAI at home and abroad, much attention has been drawn to it. However, currently, researchers cannot utterly explain the oxidation mechanism during the process of air injection. The key problem that whether the self-ignition of light crude oil could happen in low-temperature oxidation situation is still unclear. Laboratory research results show that low-temperature oxidation didn't increase the temperature too much, which is contradictory to pilot test. Air injection project in field shows that self-ignition of crude oil did occur, which significantly improved oil recovery. Therefore, it is necessary to conduct a thorough research to the theory of the temperature rising in crude oil oxidation during air injection.The goal of this paper is to predict the self-ignition time of crude oil, meanwhile, establish energy conservation equation and oxygen mass conservation equation, in which many influence factors should be considered. First of all, combined theories of the subjects of physical and chemical seepage, thermal dynamics and heat transfer to build up the prediction model of spontaneous ignition of crude oil. Then, through independently-developed thermal monitoring instrument, a laboratory experiment of temperature change of light crude oil under different conditions was carried out. The experiment found that the crude oil increase to 2-8? under experimental conditions. There wasn't a big temperature variation and didn't detect spontaneous ignition under the experimental conditions.On the basis of the study above, the model was revised through the experimental data, and also the veracity and reliability of the model was verified by the experimental data. Meanwhile, sensitivity analysis of the model was carried out to study parameters which affected the oxidation process. Such as injection time, porosity, activation energy, reaction rate etc. The results showed that:temperature peak position near the injection well, compared with other parameters, activation energy was one of the most important factors controlling the spontaneous ignition, which can significantly increase the peak temperature by decreasing a little bit Temperature rising of crude oil oxidation under reservoir condition was studied through mechanism model established by reservoir numerical simulation software CMG Simulation results showed that the initial reservoir temperature rose from 100? to 245 ?, proving that the existence of high temperature rise of light crude oil oxidation and self-ignition potential.This paper studied the temperature change of crude oil oxidation during air injection through experiments and numerical simulation, the effect of different parameters on crude oil self-ignition was estimated, the preliminary exploration to the theory of spontaneous ignition of air injection displacement was conducted, which had a certain reference value and guiding significance to further study of air injection displacement theory.