| With the ever-increasing proportion of heavy oil in the country’s crude oil production,the efficiency recovery technique gets more attention.Air injection enhanced oil recovery technology is a cost-effective method for enhanced oil recovery,which not only has a wide range of air source,low cost,high oil displacement efficiency.The impact of regions,oil properties,reservoir conditions to the field application is small.Compared with other gas injection technology,air injection enhanced oil recovery technology has the role both N2 and CO2 flooding but there is synergy exothermic and oxidative cleavage of the modified process.Oxidation will happen when air injects to formation and which can be divided into low temperature oxidation and high temperature oxidation(fire flooding)according to the reaction temperature.Therefore low-temperature oxidation of resin and asphaltene are important factor must be considered in the process of air injection.Heavy oil of Lukeqin as raw material,isolated resin and asphaltene to low temperature oxidation experiments were conducted to study the effects of reaction temperature,time and organometallic zinc catalyst.As the reaction temperature raising,secondary asphaltene and coke content of low temperature oxidation products was increase by S curve trend.As the reaction time long,secondary asphaltene content increases linearly but asphaltene in coking reaction does not occur early and late increased rapidly.organometallic zinc catalyst can promote low-temperature oxidation and cleavage reaction of resins and asphaltenes.The secondary asphaltenes and coke content are higher than non-catalytic oxidation of the same conditions.In this paper,we first time to study he structural characteristics of the low-temperature oxidation product of resin and asphaltene.The product of resin low-temperature oxidation was isolated as n-heptane solubles and secondary asphaltene.The product of asphaltene low-temperature oxidation was separated into of toluene-soluble and coke.Using infrared spectroscopy,elemental analysis,nuclear magnetic resonance 1H-NMR and X-ray diffraction analysis of the structure changes of low-temperature oxidation product.It could be the important supplement to TG of resin and asphaltene.Resin’s oxidation product structure analysis results shows that the heptane soluble molecules polar,aromaticity and olefin content was increase over the crude resin and alkane structure content was decreases with the increasing temperature and reaction time.Under the conditions of catalytic oxidation,n-heptane-soluble polar,aromaticity and olefin content was further increase compared with non-catalytic oxidation and alkanes structure content lower.Secondary asphaltene molecules polar,aromaticity oil higher than the raw resin and raw asphaltene.When Adding organometallic zinc catalyst,secondary asphaltenes alkyl structure higher crude oil asphaltenes and non-catalytic oxidation,molecular polarity,aromaticity and unsaturated olefin content is higher than crude oil asphaltenes and non-catalytic oxidation.Asphaltene oxidation product structure analysis results shows that toluene soluble molecules polarity,aromaticity and olefin content higher than raw aspaltene and decreased with the increasing of temperature,increasing the paraffin structure content.After the addition of the catalyst,toluene soluble molecules polar weakened lower aromaticity increased alkane structure.Coke molecular polarity,aromaticity and condensation enhanced significantly than the crude oil asphaltene.After catalyst coke product content higher than non-catalytic oxidation and aromatic degree higher than the crude raw asphaltenes and non-catalytic oxidation product. |
