Experimental And Theoretical Study On Kinetic Characteristic And Pahse Behavior Of Light Crude Oil During High Pressure Air Injection Process

Since the first case of high pressure air injection(HPAI)technique has been applied in light oil reservoir of Buffalo oil field in south Dakota,USA in 1970s,in the past fifty years,remarkable achievements have been made in the laboratory study of displacement mechanism and field application of the HPAI technique.Different from the traditional thermal enhanced oil recovery technique such as cyclic steam and in situ combustion,HPAI technique doesn't need complex supporting facility,also the other characteristics such as low cost and abundant resources will be perfectly fit for the problem of shortage of air supply in China.But so far,in academia there have not been a clearly understanding of the displacement mechanism and oxidation reaction of high pressure air injection,furthermore these has not been a systematical study of the phase behavior of crude oil during the air injection process.So based on the above existing problems,a comprehensive survey about the laboratory study of high pressure air injection have been completed and the following research has been conducted:Based on the crude oil of J reservoir of Changqing oil field,the influence of temperature,time,pressure,water saturation and oxygen concentration on crude oil oxidation behavior have been systematically analyzed by the high pressure oxidation tube experiment.The property changing law of crude oil during the oxidation process has been studied by the pressure monitoring and component analysis.The crude oil has been tested by TG-DSC(thermogravimetry-differential scanning calorimetry)and TG-FTIR(thermogravimetry-fourier transform infrared spectroscopy)and the results have been analyzed by kinetic model.The kinetic analysis method has been applied to study the oil oxidation process.The Arrhenius model has been applied to calculate the kinetic parameters and the Coats-Resfern and Ingraham-Marrier model has been applied to verify the results.Besides of that,based on the harrcourt-Esson model,the instant activation energy has been firstly introduced to analyze the changing trend of kinetic parameters.The results showed that in the heating process,three different regions such as low temperature oxidation,fuel deposition and high pressure oxidation have been distinguished.The metal compounds in the formation rock and water of J reservoir have been measured by X-ray fluorescence and ion chromatography.Based on the concentration,eight metal compounds have been chosen to analyze the catalytic effect on the crude oil oxidation process.Based on the calculated kinetic parameters,these metal compound have classified into four type.The comprehensive influence of formation rock and water has been investigated by TG-FTIR at different temperature level.The results showed that at reservoir temperature,the samples can't evaporate effectively.At low temperature oxidation stage,formation rock will led to the increment of activation while the bond scission reactions will still react under the thermal compensation condition and generate certain amount of carbon dioxide.At high temperature oxidation stage,the band scission reactions will be reacted effectively and produce a large amount of carbon dioxide so that generated steady flue gas flooding in the reservoir.The phase behavior of crude oil during the air injection process has been investigated by PVT physical modeling experiment.The changing of the compounds in both air and oil phase during the air-oil and flue gas-oil multiple contacts process have been investigated respectively.By comparing the physical parameters of two experiments,the different phase behavior of crude oil have been analyzed.During the air-oil contact process,due to the low generataion of carbon dioxide and carbon monoxide,the extract ability of air phase is limited,so the compounds of oil phase did not change much.In the flue gas-oil contact process,the main compounds of air phase is light hydrocarbon,so it is able to extract more hydrocarbon from the oil phase.During the flue gas-oil contacting process,the nitrogen and carbon dioxide were taken away by the old oil,so the compounds of the air phase is more similar to the oil phase.