Study On The Variation Of Crude Oil Properties During In-situ Combustion Upgrading Process

The complex properties and high content of asphaltene of heavy oil in the formation result in especially poor fluidity,which greatly increases the difficulty of mining,oil-water separation and transportation.The use of in-situ combustion(ISC)technology for upgrading is a potential method to solve this series of problems.Therefore,studying the changes in the properties of heavy oil during the ISC process can provide a theoretical basis for the research of the mechanism of ISCIn this paper,the oil samples produced by ISC field test were used.The properties of the crude oil in the combustion process were analyzed by Fourier transform infrared spectroscopy(FTIR)and gas chromatography-mass spectrometry(GC-MS).The reaction characteristics and functional group variation of residual oil(500°C+ pseudo-component)in the low temperature oxidation stage were analyzed by using the kinetic cell experiment and Fourier transform ion cyclotron resonance mass spectrometry(FTICR-MS).The oxidation and pyrolysis behavior of heavy oil in different atmosphere was also analyzed by thermogravimetry/differential mass spectrometry(TG/DSC-MS)and pyrolysis mass spectrometry(Py-GC/MS).The results show that the residue component and the whole oil component undergo a combination of the oxygenation reaction and the cracking reaction in the low temperature oxidation stage(LTO).On the one hand,the mass range of the acidic compound is expanded.On the other hand,there exists the mutual conversion from acidic oxygen and nitrogen to other substances.The LTO reaction promotes fuel deposition(FD)and causes the advance of high temperature oxidation(HTO).