轻质油静态低温氧化原油与气体变化规律室内实验研究

Experimental Study on Gas and Oil Composition Through Static Low Temperature Oxidation of Light Crude Oil

为了研究轻质油注空气开采过程中低温氧化后原油与气体组成的变化,对Q131井轻质油开展了不同温度下的室内低温氧化实验。对氧化前后的原油进行轻烃、饱和烃以及芳香烃的气相色谱分析,并采集尾气进行气体组成分析。结果表明,低温氧化后,C_(4)~C_(7)轻烃化合物中异构烷烃较正构烷烃、正构烷烃较环烷烃含量逐渐增加,环烷烃的侧链烷基越多、侧链烷基越长越易断裂;饱和烃中轻重比(∑nC_(21-)/∑nC_(22+))随温度升高逐渐增加,姥植比(Pr/Ph)和奇偶优势比(OEP)基本保持不变;芳香烃中双环芳烃甲基萘与萘的比值、三环芳烃甲基菲与菲比值随着温度的升高增大,并且三环芳烃(菲)发生甲基取代反应的难度要高于双环芳烃(萘);尾气中,O_(2)含量随温度升高而逐渐降低,CO_(2)对温度的敏感性要高于CO,存在少量的CH_(4)与H_(2),表明低温氧化过程中伴随有化学键的键裂反应,氧气转化率随温度的升高逐渐增加。

By using the physical model of static low-temperature oxidation,the laboratory experiment based on air-injection low-temperature oxidation is conducted to test the light oil in Q131 well.The components of crude oil before and after oxidation,which incluoles light hydrocarbons,saturated hydrocarbons,aromatic hydrocarbons and tail gas,are analyzed.Studies have shown that light oil deteriorates after low temperature oxidation.Light hydrocarbons,saturated hydrocarbons and aromatic hydrocarbons in crude oil are significantly affected by low temperature oxidation.Their change is directly related to temperature.Specifically,as the temperature rises,the content of isoparaffins and n-alkanes increases.As the number and length of the side chain alkyl groups in cycloalkanes increases,they are more likely to break.Besides,six-membered ring is more likely to react than five-membered ring.The longer the carbon chain in saturated hydrocarbons,the easier it is to react with oxygen at low temperature.Low-temperature oxidation does not selectively break up n-alkanes with an odd number or even number of carbon atoms.The isoprenoids are stable during low-temperature oxidation and are not likely to undergo low temperature oxidation.The substitution of methyl with naphthalene and phenanthrene in aromatic hydrocarbons is likely to occur.The alpha carbon atoms are more likely to react than the beta carbon atoms.The bicyclic aromatic hydrocarbons(naphtha-lene)are more susceptible to substitution reaction than the tricyclic aromatic hydrocarbons(phenanthrene).Among the gas components,the O_(2)content is significantly affected by temperature.Among the carbon oxides,CO_(2)is more sensitive to temperature.The conversation rate of oxygen is relatively low during low-temperature oxidation.