生物降解作用对原油中烷基萘分布与组成特征的影响

烷基萘系列是指示热演化的重要地球化学参数。通过对辽河油田冷东地区遭受不同生物降解作用的14个油样的分析,对比不同程度生物降解原油中二甲基萘系列、三甲基萘系列和四甲基萘系列浓度的变化,确定了烷基萘系列的生物降解顺序是二甲基萘系列>三甲基萘系列>四甲基萘系列。通过研究烷基萘成熟度参数与生物降解程度之间的关系,表明这些参数已不能为生物降解原油提供有效的成熟度信息,其原因是在生物降解过程中热稳定性高的异构体的浓度较热稳定低的异构体的浓度下降幅度大,说明前者抗生物降解的能力低于后者。

The effect of biodegradation on the distribution and composition of alkylnaphthalene series in biodegraded crude oils

Alkylnaphthalene series are the important geochemical parameters to indicate the thermal evolution. Fourteen biodegraded oil samples from Lengdong Oilfield of the Liaohe Basin have been analyzed. The distributions and relative compositions of dimethylnaphthalenes (DMNs), trimethylnaphthalenes (TMNs) and tetramethylnaphthalenes (TeMNs) in differently biodegraded oils have been studied. The biodegradation sequence has been set up, that is, the resistant ability for alkylnaphthalene series to biodegradation is DMNs＜TMNs＜TeMNs. The relationship between biodegradation degree and the maturity indicators related to alkylnaphthalene series has been studied, showing that they can not supply effective maturity information for biodegraded oils. The reason is that the resistant ability for thermally stable alkylnaphthalene isomer to biodegradation is less than the thermally unstable alkylnaphthalene isomer.