轮南低凸起原油中金刚烷类化合物的相分馏响应

Response of phase fractionation of diamantane compounds in crude oil of Lunnan uplift

相分馏作用是我国海相碳酸盐岩油气藏调整与改造(破坏)的一种重要形式。目前,国内外对于相分馏作用的识别标志主要局限于C7系列化合物(甲基环己烷、正庚烷、甲苯)的分异比。由于轻烃组分(C5—C8)稳定性较差,水洗作用、氧化降解作用、温压条件的改变、油气运移,甚至在分析测试的过程中,均会导致轻烃类组分发生不同程度的消耗与变化,从而导致利用C7系列化合物来判识相分馏过程存在一定的不准确性,而金刚烷类化合物具较强抗热解和生物降解能力。对塔里木盆地典型的气洗相分馏作用区(轮南低凸起地区)原油金刚烷系列进行系统分析认为,经气洗改造后的原油具有1-甲基金刚烷富集,1,3-二甲基金刚烷、1,4-二甲基金刚烷(顺)、1,4-二甲基金刚烷(反)、3-甲基-1-乙基金刚烷贫化的特征。因此,金刚烷类化合物可以作为有效示踪相分馏作用的识别标志。

Phase fractionation is an important form in the process of adjustment and reconstruction of reservoir for marine carbonate rock measures in our country. Nowadays, identification mark of phase fractionation is mainly limited to the differentiate ratio of C7 series compound（methylcyclohexane, normal heptane and mehtylbenzene）. However, light hydrocarbon such as C5-C6 is so instable thai oxidative degradation, water washing, changing of temperature and pressure conditions, hydrocarbon migration and even in the process of analysis and test will alternate its composition. Therefore, it is an inaccurate way to apply the C7 series compound as an identification sign of phase fractionation action, diamantane compounds is a kind of hydrocarbon compound with a strong anti-thermolysis and antibiodegradation capability. Through the analysis of diamantane series of crude oil in the typical phase fractionation action area（Lunnan uplift area） of gas washing in Tarim Basin, it is believed that the crude oil after gas washing is characterized by 1-methyladamantane enrichment and depletion of 1,3-dimethyladamantane, 1,4-dimethyladamantane, and 3-methyl-1-ethyladamantane. Therefore, the diamantane compounds can be used as an effective tracking mark of phase fractionation.